Compounds which inhibit or antagonize the biosynthesis or actions of phosphodiesterases.
A potent cyclic nucleotide phosphodiesterase inhibitor; due to this action, the compound increases cyclic AMP and cyclic GMP in tissue and thereby activates CYCLIC NUCLEOTIDE-REGULATED PROTEIN KINASES
Enzymes that catalyze the hydrolysis of CYCLIC AMP to form adenosine 5'-phosphate. The enzymes are widely distributed in animal tissue and control the level of intracellular cyclic AMP. Many specific enzymes classified under this heading demonstrate additional spcificity for 3',5'-cyclic IMP and CYCLIC GMP.
A phosphodiesterase 4 inhibitor with antidepressant properties.
A class of enzymes that catalyze the hydrolysis of one of the two ester bonds in a phosphodiester compound. EC 3.1.4.
'Purines' is a term used in medical biochemistry to refer to naturally occurring heterocyclic aromatic organic compounds, which include adenine and guanine (components of nucleotides and nucleic acids), and are formed in the body from purine bases through various metabolic processes.
Inhibitor of phosphodiesterases.
An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH.
Enzymes that catalyze the hydrolysis of cyclic GMP to yield guanosine-5'-phosphate.
A cyclic nucleotide phosphodiesterase subfamily that is found predominantly in inflammatory cells and may play a role in the regulation of CELL-MEDIATED IMMUNITY. The enzyme family includes over twenty different variants that occur due to multiple ALTERNATIVE SPLICING of the mRNA of at least four different genes.
A methyl xanthine derivative from tea with diuretic, smooth muscle relaxant, bronchial dilation, cardiac and central nervous system stimulant activities. Theophylline inhibits the 3',5'-CYCLIC NUCLEOTIDE PHOSPHODIESTERASE that degrades CYCLIC AMP thus potentiates the actions of agents that act through ADENYLYL CYCLASES and cyclic AMP.
Compounds that specifically inhibit PHOSPHODIESTERASE 3.
Compounds that specifically inhibit PHOSPHODIESTERASE 4.
Guanosine cyclic 3',5'-(hydrogen phosphate). A guanine nucleotide containing one phosphate group which is esterified to the sugar moiety in both the 3'- and 5'-positions. It is a cellular regulatory agent and has been described as a second messenger. Its levels increase in response to a variety of hormones, including acetylcholine, insulin, and oxytocin and it has been found to activate specific protein kinases. (From Merck Index, 11th ed)
A positive inotropic cardiotonic agent with vasodilator properties. It inhibits cAMP phosphodiesterase type 3 activity in myocardium and vascular smooth muscle. Milrinone is a derivative of amrinone and has 20-30 times the inotropic potency of amrinone.
A cyclic nucleotide phosphodiesterase subfamily that is inhibited by the binding of CYCLIC GMP to an allosteric domain found on the enzyme and through phosphorylation by regulatory kinases such as PROTEIN KINASE A and PROTEIN KINASE B. The two members of this family are referred to as type 3A, and type 3B, and are each product of a distinct gene. In addition multiple enzyme variants of each subtype can be produced due to multiple alternative mRNA splicing.
Compounds that specifically inhibit PHOSPHODIESTERASE 5.
An alkaloid found in opium but not closely related to the other opium alkaloids in its structure or pharmacological actions. It is a direct-acting smooth muscle relaxant used in the treatment of impotence and as a vasodilator, especially for cerebral vasodilation. The mechanism of its pharmacological actions is not clear, but it apparently can inhibit phosphodiesterases and it may have direct actions on calcium channels.
A group of compounds that are derivatives of oxo-pyrrolidines. A member of this group is 2-oxo pyrrolidine, which is an intermediate in the manufacture of polyvinylpyrrolidone. (From Merck Index, 11th ed)
A cyclic nucleotide phosphodiesterase subfamily that is highly specific for CYCLIC GMP. It is found predominantly in vascular tissue and plays an important role in regulating VASCULAR SMOOTH MUSCLE contraction.
A phosphoric diester hydrolase that removes 5'-nucleotides from the 3'-hydroxy termini of 3'-hydroxy-terminated OLIGONUCLEOTIDES. It has low activity towards POLYNUCLEOTIDES and the presence of 3'-phosphate terminus on the substrate may inhibit hydrolysis.
A CALCIUM and CALMODULIN-dependent cyclic nucleotide phosphodiesterase subfamily. The three members of this family are referred to as type 1A, type 1B, and type 1C and are each product of a distinct gene. In addition, multiple enzyme variants of each subtype can be produced due to multiple alternative mRNA splicing. Although the type 1 enzymes are classified as 3',5'-cyclic-AMP phosphodiesterases (EC 3.1.4.17), some members of this class have additional specificity for CYCLIC GMP.
Nucleoside-2',3'-cyclic phosphate nucleotidohydrolase. Enzymes that catalyze the hydrolysis of the 2'- or 3'- phosphate bonds of 2',3'-cyclic nucleotides. Also hydrolyzes nucleoside monophosphates. Includes EC 3.1.4.16 and EC 3.1.4.37. EC 3.1.4.-.
Potent activator of the adenylate cyclase system and the biosynthesis of cyclic AMP. From the plant COLEUS FORSKOHLII. Has antihypertensive, positive inotropic, platelet aggregation inhibitory, and smooth muscle relaxant activities; also lowers intraocular pressure and promotes release of hormones from the pituitary gland.
A METHYLXANTHINE derivative that inhibits phosphodiesterase and affects blood rheology. It improves blood flow by increasing erythrocyte and leukocyte flexibility. It also inhibits platelet aggregation. Pentoxifylline modulates immunologic activity by stimulating cytokine production.
A cyclic nucleotide derivative that mimics the action of endogenous CYCLIC AMP and is capable of permeating the cell membrane. It has vasodilator properties and is used as a cardiac stimulant. (From Merck Index, 11th ed)
Sulfones are a class of organic compounds containing the functional group with a sulfur atom bonded to two oxygen atoms and another organic group, widely used in pharmaceuticals, particularly for the treatment of bacterial infections, leprosy, and certain types of cancer.
Purine bases found in body tissues and fluids and in some plants.
A long-acting derivative of cyclic AMP. It is an activator of cyclic AMP-dependent protein kinase, but resistant to degradation by cyclic AMP phosphodiesterase.
Cyclic nucleotides are closed-chain molecules formed from nucleotides (ATP or GTP) through the action of enzymes called cyclases, functioning as second messengers in various cellular signaling pathways, with cAMP and cGMP being the most prominent members.
**Pyridazine** is a heterocyclic organic compound, consisting of a six-membered ring containing two nitrogen atoms, which is a basic structure found in certain pharmaceuticals and natural compounds, though it does not have a specific medical definition itself as a component or condition.
An enzyme of the lyase class that catalyzes the formation of CYCLIC AMP and pyrophosphate from ATP. EC 4.6.1.1.
A series of heterocyclic compounds that are variously substituted in nature and are known also as purine bases. They include ADENINE and GUANINE, constituents of nucleic acids, as well as many alkaloids such as CAFFEINE and THEOPHYLLINE. Uric acid is the metabolic end product of purine metabolism.
Isopropyl analog of EPINEPHRINE; beta-sympathomimetic that acts on the heart, bronchi, skeletal muscle, alimentary tract, etc. It is used mainly as bronchodilator and heart stimulant.
A selective phosphodiesterase inhibitor with vasodilating and positive inotropic activity that does not cause changes in myocardial oxygen consumption. It is used in patients with CONGESTIVE HEART FAILURE.
A group of indole-indoline dimers which are ALKALOIDS obtained from the VINCA genus of plants. They inhibit polymerization of TUBULIN into MICROTUBULES thus blocking spindle formation and arresting cells in METAPHASE. They are some of the most useful ANTINEOPLASTIC AGENTS.
A positive inotropic cardiotonic (CARDIOTONIC AGENTS) with vasodilator properties, phosphodiesterase 3 inhibitory activity, and the ability to stimulate calcium ion influx into the cardiac cell.
A drug combination that contains THEOPHYLLINE and ethylenediamine. It is more soluble in water than theophylline but has similar pharmacologic actions. It's most common use is in bronchial asthma, but it has been investigated for several other applications.
A species of the true toads, Bufonidae, widely distributed in the United States and Europe.
A group of enzymes that are dependent on CYCLIC AMP and catalyze the phosphorylation of SERINE or THREONINE residues on proteins. Included under this category are two cyclic-AMP-dependent protein kinase subtypes, each of which is defined by its subunit composition.
A cyclic nucleotide phosphodiesterase subfamily that is activated by the binding of CYCLIC GMP to an allosteric domain found on the enzyme. Multiple enzyme variants of this subtype can be produced due to multiple alternative mRNA splicing. The subfamily is expressed in a broad variety of tissues and may play a role in mediating cross-talk between CYCLIC GMP and CYCLIC CMP pathways. Although the type 2 enzymes are classified as 3',5'-cyclic-AMP phosphodiesterases (EC 3.1.4.17), members of this class have additional specificity for CYCLIC GMP.
The relationship between the dose of an administered drug and the response of the organism to the drug.
Specialized cells that detect and transduce light. They are classified into two types based on their light reception structure, the ciliary photoreceptors and the rhabdomeric photoreceptors with MICROVILLI. Ciliary photoreceptor cells use OPSINS that activate a PHOSPHODIESTERASE phosphodiesterase cascade. Rhabdomeric photoreceptor cells use opsins that activate a PHOSPHOLIPASE C cascade.
A cyclic nucleotide phosphodiesterase subfamily that is highly specific for CYCLIC GMP. It is found predominantly in the outer segment PHOTORECEPTOR CELLS of the RETINA. It is comprised of two catalytic subunits, referred to as alpha and beta, that form a dimer. In addition two regulatory subunits, referred to as gamma and delta, modulate the activity and localization of the enzyme.
The rate dynamics in chemical or physical systems.
N-(1-Oxobutyl)-cyclic 3',5'-(hydrogen phosphate)-2'-butanoate guanosine. A derivative of cyclic GMP. It has a higher resistance to extracellular and intracellular phosphodiesterase than cyclic GMP.
Piperazines are a class of heterocyclic organic compounds containing a seven-membered ring with two nitrogen atoms at positions 1 and 4, often used in pharmaceuticals as smooth muscle relaxants, antipsychotics, antidepressants, and antihistamines, but can also be found as recreational drugs with stimulant and entactogen properties.
A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.
An enzyme that catalyzes the conversion of GTP to 3',5'-cyclic GMP and pyrophosphate. It also acts on ITP and dGTP. (From Enzyme Nomenclature, 1992) EC 4.6.1.2.
A phosphodiesterase inhibitor that blocks uptake and metabolism of adenosine by erythrocytes and vascular endothelial cells. Dipyridamole also potentiates the antiaggregating action of prostacyclin. (From AMA Drug Evaluations Annual, 1994, p752)
The inability in the male to have a PENILE ERECTION due to psychological or organ dysfunction.
A potent vasodilator agent that increases peripheral blood flow.
Phthalazines are heterocyclic aromatic organic compounds consisting of a benzene ring fused with a 1,2-diazine ring, which have been used as intermediates in the synthesis of various pharmaceuticals and dyes.
Pyridine derivatives with one or more keto groups on the ring.
Nucleotides in which the base moiety is substituted with one or more sulfur atoms.
A nucleoside that is composed of ADENINE and D-RIBOSE. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter.
N-Isopropyl-N-phenyl-adenosine. Antilipemic agent. Synonym: TH 162.
A cyclic nucleotide phosphodiesterase subfamily that is highly specific for CYCLIC AMP. Several isoforms of the enzyme type exist, each with its own tissue localization. The isoforms are encoded by at least two genes and are a product of multiple alternative splicing of their mRNAs.
A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.
Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.
Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.
A class of cyclic prostaglandins that contain the 6,9-epoxy bond. Endogenous members of this family are biosynthesized enzymatically from PROSTAGLANDIN ENDOPEROXIDES.
The state of the PENIS when the erectile tissue becomes filled or swollen (tumid) with BLOOD and causes the penis to become rigid and elevated. It is a complex process involving CENTRAL NERVOUS SYSTEM; PERIPHERAL NERVOUS SYSTEMS; HORMONES; SMOOTH MUSCLES; and vascular functions.
A group of cyclic GMP-dependent enzymes that catalyze the phosphorylation of SERINE or THREONINE residues of proteins.
Systems in which an intracellular signal is generated in response to an intercellular primary messenger such as a hormone or neurotransmitter. They are intermediate signals in cellular processes such as metabolism, secretion, contraction, phototransduction, and cell growth. Examples of second messenger systems are the adenyl cyclase-cyclic AMP system, the phosphatidylinositol diphosphate-inositol triphosphate system, and the cyclic GMP system.
The increase in a measurable parameter of a PHYSIOLOGICAL PROCESS, including cellular, microbial, and plant; immunological, cardiovascular, respiratory, reproductive, urinary, digestive, neural, musculoskeletal, ocular, and skin physiological processes; or METABOLIC PROCESS, including enzymatic and other pharmacological processes, by a drug or other chemical.
A group of compounds with the heterocyclic ring structure of benzo(c)pyridine. The ring structure is characteristic of the group of opium alkaloids such as papaverine. (From Stedman, 25th ed)
A free radical gas produced endogenously by a variety of mammalian cells, synthesized from ARGININE by NITRIC OXIDE SYNTHASE. Nitric oxide is one of the ENDOTHELIUM-DEPENDENT RELAXING FACTORS released by the vascular endothelium and mediates VASODILATION. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic GUANYLATE CYCLASE and thus elevates intracellular levels of CYCLIC GMP.
Analogs or derivatives of prostaglandins E that do not occur naturally in the body. They do not include the product of the chemical synthesis of hormonal PGE.
Drugs used to cause dilation of the blood vessels.
A heterotrimeric GTP-binding protein that mediates the light activation signal from photolyzed rhodopsin to cyclic GMP phosphodiesterase and is pivotal in the visual excitation process. Activation of rhodopsin on the outer membrane of rod and cone cells causes GTP to bind to transducin followed by dissociation of the alpha subunit-GTP complex from the beta/gamma subunits of transducin. The alpha subunit-GTP complex activates the cyclic GMP phosphodiesterase which catalyzes the hydrolysis of cyclic GMP to 5'-GMP. This leads to closure of the sodium and calcium channels and therefore hyperpolarization of the rod cells. EC 3.6.1.-.
Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding.
A powerful vasodilator used in emergencies to lower blood pressure or to improve cardiac function. It is also an indicator for free sulfhydryl groups in proteins.
Tetrazoles are heterocyclic organic compounds containing a 1,3,5-triazole ring with an additional nitrogen atom, often used in pharmaceuticals as bioisosteres for carboxylic acid groups due to their isoelectronic nature and similar hydrogen bonding capabilities.
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
Compounds containing 1,3-diazole, a five membered aromatic ring containing two nitrogen atoms separated by one of the carbons. Chemically reduced ones include IMIDAZOLINES and IMIDAZOLIDINES. Distinguish from 1,2-diazole (PYRAZOLES).
An ENTEROTOXIN from VIBRIO CHOLERAE. It consists of two major protomers, the heavy (H) or A subunit and the B protomer which consists of 5 light (L) or B subunits. The catalytic A subunit is proteolytically cleaved into fragments A1 and A2. The A1 fragment is a MONO(ADP-RIBOSE) TRANSFERASE. The B protomer binds cholera toxin to intestinal epithelial cells, and facilitates the uptake of the A1 fragment. The A1 catalyzed transfer of ADP-RIBOSE to the alpha subunits of heterotrimeric G PROTEINS activates the production of CYCLIC AMP. Increased levels of cyclic AMP are thought to modulate release of fluid and electrolytes from intestinal crypt cells.
2-, 3-, or 4-Pyridinecarboxylic acids. Pyridine derivatives substituted with a carboxy group at the 2-, 3-, or 4-position. The 3-carboxy derivative (NIACIN) is active as a vitamin.
An eicosanoid, derived from the cyclooxygenase pathway of arachidonic acid metabolism. It is a stable and synthetic analog of EPOPROSTENOL, but with a longer half-life than the parent compound. Its actions are similar to prostacyclin. Iloprost produces vasodilation and inhibits platelet aggregation.
Structurally related forms of an enzyme. Each isoenzyme has the same mechanism and classification, but differs in its chemical, physical, or immunological characteristics.
The portion of a retinal rod cell situated between the ROD INNER SEGMENT and the RETINAL PIGMENT EPITHELIUM. It contains a stack of photosensitive disk membranes laden with RHODOPSIN.
One of two major pharmacologically defined classes of adrenergic receptors. The beta adrenergic receptors play an important role in regulating CARDIAC MUSCLE contraction, SMOOTH MUSCLE relaxation, and GLYCOGENOLYSIS.
Heterocyclic rings containing three nitrogen atoms, commonly in 1,2,4 or 1,3,5 or 2,4,6 formats. Some are used as HERBICIDES.
Oxadiazoles are heterocyclic organic compounds consisting of a five-membered ring containing two carbon atoms, one nitrogen atom, and two oxygen atoms (one as a part of the oxadiazole ring and the other as a substituent or part of a larger molecule), which can exist in various isomeric forms and are known for their versatile biological activities, including anti-inflammatory, antiviral, antibacterial, and antitumor properties.
Drugs that selectively bind to and activate beta-adrenergic receptors.
Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.
A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.
A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine's most notable pharmacological effect is as a central nervous system stimulant, increasing alertness and producing agitation. It also relaxes SMOOTH MUSCLE, stimulates CARDIAC MUSCLE, stimulates DIURESIS, and appears to be useful in the treatment of some types of headache. Several cellular actions of caffeine have been observed, but it is not entirely clear how each contributes to its pharmacological profile. Among the most important are inhibition of cyclic nucleotide PHOSPHODIESTERASES, antagonism of ADENOSINE RECEPTORS, and modulation of intracellular calcium handling.
A potent natriuretic and vasodilatory peptide or mixture of different-sized low molecular weight PEPTIDES derived from a common precursor and secreted mainly by the HEART ATRIUM. All these peptides share a sequence of about 20 AMINO ACIDS.
A widely used non-cardioselective beta-adrenergic antagonist. Propranolol has been used for MYOCARDIAL INFARCTION; ARRHYTHMIA; ANGINA PECTORIS; HYPERTENSION; HYPERTHYROIDISM; MIGRAINE; PHEOCHROMOCYTOMA; and ANXIETY but adverse effects instigate replacement by newer drugs.
Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)
Agents that have a strengthening effect on the heart or that can increase cardiac output. They may be CARDIAC GLYCOSIDES; SYMPATHOMIMETICS; or other drugs. They are used after MYOCARDIAL INFARCT; CARDIAC SURGICAL PROCEDURES; in SHOCK; or in congestive heart failure (HEART FAILURE).
The action of a drug in promoting or enhancing the effectiveness of another drug.
The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.
(11 alpha,13E,15S)-11,15-Dihydroxy-9-oxoprost-13-en-1-oic acid (PGE(1)); (5Z,11 alpha,13E,15S)-11,15-dihydroxy-9-oxoprosta-5,13-dien-1-oic acid (PGE(2)); and (5Z,11 alpha,13E,15S,17Z)-11,15-dihydroxy-9-oxoprosta-5,13,17-trien-1-oic acid (PGE(3)). Three of the six naturally occurring prostaglandins. They are considered primary in that no one is derived from another in living organisms. Originally isolated from sheep seminal fluid and vesicles, they are found in many organs and tissues and play a major role in mediating various physiological activities.
A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.
Elements of limited time intervals, contributing to particular results or situations.
A stable adenosine A1 and A2 receptor agonist. Experimentally, it inhibits cAMP and cGMP phosphodiesterase activity.
Naphthyridines are a class of heterocyclic organic compounds containing a naphthyridine nucleus, which is a polycyclic aromatic hydrocarbon made up of two benzene rings fused to a pyridine ring, and they have been studied for their potential pharmacological properties, including as antimicrobial, antiviral, and anticancer agents.
A compound consisting of dark green crystals or crystalline powder, having a bronze-like luster. Solutions in water or alcohol have a deep blue color. Methylene blue is used as a bacteriologic stain and as an indicator. It inhibits GUANYLATE CYCLASE, and has been used to treat cyanide poisoning and to lower levels of METHEMOGLOBIN.
The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.
A group of enzymes within the class EC 3.6.1.- that catalyze the hydrolysis of diphosphate bonds, chiefly in nucleoside di- and triphosphates. They may liberate either a mono- or diphosphate. EC 3.6.1.-.
Compounds with a six membered aromatic ring containing NITROGEN. The saturated version is PIPERIDINES.
A heat-stable, low-molecular-weight activator protein found mainly in the brain and heart. The binding of calcium ions to this protein allows this protein to bind to cyclic nucleotide phosphodiesterases and to adenyl cyclase with subsequent activation. Thereby this protein modulates cyclic AMP and cyclic GMP levels.
A purine base and a fundamental unit of ADENINE NUCLEOTIDES.
An opisthobranch mollusk of the order Anaspidea. It is used frequently in studies of nervous system development because of its large identifiable neurons. Aplysiatoxin and its derivatives are not biosynthesized by Aplysia, but acquired by ingestion of Lyngbya (seaweed) species.
The external reproductive organ of males. It is composed of a mass of erectile tissue enclosed in three cylindrical fibrous compartments. Two of the three compartments, the corpus cavernosa, are placed side-by-side along the upper part of the organ. The third compartment below, the corpus spongiosum, houses the urethra.
The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).
That phase of a muscle twitch during which a muscle returns to a resting position.
A slowly hydrolyzed CHOLINERGIC AGONIST that acts at both MUSCARINIC RECEPTORS and NICOTINIC RECEPTORS.
A 29-amino acid pancreatic peptide derived from proglucagon which is also the precursor of intestinal GLUCAGON-LIKE PEPTIDES. Glucagon is secreted by PANCREATIC ALPHA CELLS and plays an important role in regulation of BLOOD GLUCOSE concentration, ketone metabolism, and several other biochemical and physiological processes. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p1511)
Quinolines substituted in any position by one or more amino groups.
The process of cleaving a chemical compound by the addition of a molecule of water.
A diverse group of agents, with unique chemical structures and biochemical requirements, which generate NITRIC OXIDE. These compounds have been used in the treatment of cardiovascular diseases and the management of acute myocardial infarction, acute and chronic congestive heart failure, and surgical control of blood pressure. (Adv Pharmacol 1995;34:361-81)
Increased VASCULAR RESISTANCE in the PULMONARY CIRCULATION, usually secondary to HEART DISEASES or LUNG DISEASES.
An ionophorous, polyether antibiotic from Streptomyces chartreusensis. It binds and transports CALCIUM and other divalent cations across membranes and uncouples oxidative phosphorylation while inhibiting ATPase of rat liver mitochondria. The substance is used mostly as a biochemical tool to study the role of divalent cations in various biological systems.
Compounds that bind to and block the stimulation of PURINERGIC P1 RECEPTORS.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
A subclass of adenosine A2 receptors found in LEUKOCYTES, the SPLEEN, the THYMUS and a variety of other tissues. It is generally considered to be a receptor for ADENOSINE that couples to the GS, STIMULATORY G-PROTEIN.
The most common and most biologically active of the mammalian prostaglandins. It exhibits most biological activities characteristic of prostaglandins and has been used extensively as an oxytocic agent. The compound also displays a protective effect on the intestinal mucosa.
A prostaglandin that is a powerful vasodilator and inhibits platelet aggregation. It is biosynthesized enzymatically from PROSTAGLANDIN ENDOPEROXIDES in human vascular tissue. The sodium salt has been also used to treat primary pulmonary hypertension (HYPERTENSION, PULMONARY).
The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.
The active sympathomimetic hormone from the ADRENAL MEDULLA. It stimulates both the alpha- and beta- adrenergic systems, causes systemic VASOCONSTRICTION and gastrointestinal relaxation, stimulates the HEART, and dilates BRONCHI and cerebral vessels. It is used in ASTHMA and CARDIAC FAILURE and to delay absorption of local ANESTHETICS.
Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers and of the diffuse projection system in the brain arising from the locus ceruleus. It is also found in plants and is used pharmacologically as a sympathomimetic.
An amine derived by enzymatic decarboxylation of HISTIDINE. It is a powerful stimulant of gastric secretion, a constrictor of bronchial smooth muscle, a vasodilator, and also a centrally acting neurotransmitter.
A sulfur-containing alkyl thionitrite that is one of the NITRIC OXIDE DONORS.
Quinoxalines are heterocyclic organic compounds consisting of a benzene fused to a pyrazine ring, which have been studied for their potential antibacterial, antifungal, and anticancer properties.
The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.
Established cell cultures that have the potential to propagate indefinitely.
A peptide hormone of about 27 amino acids from the duodenal mucosa that activates pancreatic secretion and lowers the blood sugar level. (USAN and the USP Dictionary of Drug Names, 1994, p597)
A class of cell surface receptors that prefer ADENOSINE to other endogenous PURINES. Purinergic P1 receptors are widespread in the body including the cardiovascular, respiratory, immune, and nervous systems. There are at least two pharmacologically distinguishable types (A1 and A2, or Ri and Ra).
A family of enzymes that catalyze the conversion of ATP and a protein to ADP and a phosphoprotein.
A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.
The cartilaginous and membranous tube descending from the larynx and branching into the right and left main bronchi.
Contractile activity of the MYOCARDIUM.
That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.
Adenine nucleotides are molecules that consist of an adenine base attached to a ribose sugar and one, two, or three phosphate groups, including adenosine monophosphate (AMP), adenosine diphosphate (ADP), and adenosine triphosphate (ATP), which play crucial roles in energy transfer and signaling processes within cells.
3-Mercapto-D-valine. The most characteristic degradation product of the penicillin antibiotics. It is used as an antirheumatic and as a chelating agent in Wilson's disease.
A highly basic, 28 amino acid neuropeptide released from intestinal mucosa. It has a wide range of biological actions affecting the cardiovascular, gastrointestinal, and respiratory systems and is neuroprotective. It binds special receptors (RECEPTORS, VASOACTIVE INTESTINAL PEPTIDE).
The nonstriated involuntary muscle tissue of blood vessels.
RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.
Photosensitive afferent neurons located in the peripheral retina, with their density increases radially away from the FOVEA CENTRALIS. Being much more sensitive to light than the RETINAL CONE CELLS, the rod cells are responsible for twilight vision (at scotopic intensities) as well as peripheral vision, but provide no color discrimination.
Use of electric potential or currents to elicit biological responses.
An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
A group of compounds that contain the structure SO2NH2.
A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.
The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)
A component of PHOSPHATIDYLCHOLINES or LECITHINS, in which the two hydroxy groups of GLYCEROL are esterified with fatty acids. (From Stedman, 26th ed) It counteracts the effects of urea on enzymes and other macromolecules.
The short wide vessel arising from the conus arteriosus of the right ventricle and conveying unaerated blood to the lungs.
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
Mature male germ cells derived from SPERMATIDS. As spermatids move toward the lumen of the SEMINIFEROUS TUBULES, they undergo extensive structural changes including the loss of cytoplasm, condensation of CHROMATIN into the SPERM HEAD, formation of the ACROSOME cap, the SPERM MIDPIECE and the SPERM TAIL that provides motility.
The attachment of PLATELETS to one another. This clumping together can be induced by a number of agents (e.g., THROMBIN; COLLAGEN) and is part of the mechanism leading to the formation of a THROMBUS.
A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1).
The physiological widening of BLOOD VESSELS by relaxing the underlying VASCULAR SMOOTH MUSCLE.
A general class of ortho-dihydroxyphenylalkylamines derived from tyrosine.
Pyrazines are heterocyclic organic compounds containing a six-membered ring with two nitrogen atoms at opposite positions, often responsible for the characteristic flavors and aromas found in various foods, beverages, and some biological systems, but they do not have a direct medical definition as they are not a drug, treatment, or a significant component of human physiology or pathology.
A species of the family Ranidae (true frogs). The only anuran properly referred to by the common name "bullfrog", it is the largest native anuran in North America.
The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.
Movement characteristics of SPERMATOZOA in a fresh specimen. It is measured as the percentage of sperms that are moving, and as the percentage of sperms with productive flagellar motion such as rapid, linear, and forward progression.
An NADPH-dependent enzyme that catalyzes the conversion of L-ARGININE and OXYGEN to produce CITRULLINE and NITRIC OXIDE.
Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals. They are mainly involved in blood coagulation.
Drugs that bind to but do not activate beta-adrenergic receptors thereby blocking the actions of beta-adrenergic agonists. Adrenergic beta-antagonists are used for treatment of hypertension, cardiac arrhythmias, angina pectoris, glaucoma, migraine headaches, and anxiety.
An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.
An serine-threonine protein kinase that requires the presence of physiological concentrations of CALCIUM and membrane PHOSPHOLIPIDS. The additional presence of DIACYLGLYCEROLS markedly increases its sensitivity to both calcium and phospholipids. The sensitivity of the enzyme can also be increased by PHORBOL ESTERS and it is believed that protein kinase C is the receptor protein of tumor-promoting phorbol esters.
A group of pyrido-indole compounds. Included are any points of fusion of pyridine with the five-membered ring of indole and any derivatives of these compounds. These are similar to CARBAZOLES which are benzo-indoles.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.
A chelating agent relatively more specific for calcium and less toxic than EDETIC ACID.
The action of a drug that may affect the activity, metabolism, or toxicity of another drug.
Phosphoric acid esters of inositol. They include mono- and polyphosphoric acid esters, with the exception of inositol hexaphosphate which is PHYTIC ACID.
The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.
Cyclopropanes are a class of hydrocarbons characterized by a small ring structure containing three carbon atoms, each with single bonds to the other two carbons and to hydrogen atoms, making it highly strained and reactive, which has implications for its use as an anesthetic in medicine.
Serum glycoprotein produced by activated MACROPHAGES and other mammalian MONONUCLEAR LEUKOCYTES. It has necrotizing activity against tumor cell lines and increases ability to reject tumor transplants. Also known as TNF-alpha, it is only 30% homologous to TNF-beta (LYMPHOTOXIN), but they share TNF RECEPTORS.
A class of enzymes that catalyze the conversion of a nucleotide and water to a nucleoside and orthophosphate. EC 3.1.3.-.
A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.
Twenty-carbon compounds derived from MEVALONIC ACID or deoxyxylulose phosphate.
The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
Inosine cyclic 3',5'-(hydrogen phosphate). An inosine nucleotide which acts as a mild inhibitor of the hydrolysis of cyclic AMP and cyclic GMP and as an inhibitor of cat heart cyclic AMP phosphodiesterase.
A genus of protozoa, formerly also considered a fungus. Its natural habitat is decaying forest leaves, where it feeds on bacteria. D. discoideum is the best-known species and is widely used in biomedical research.
Organic nitrogenous bases. Many alkaloids of medical importance occur in the animal and vegetable kingdoms, and some have been synthesized. (Grant & Hackh's Chemical Dictionary, 5th ed)
An alkaloid, originally from Atropa belladonna, but found in other plants, mainly SOLANACEAE. Hyoscyamine is the 3(S)-endo isomer of atropine.
Pyridines substituted in any position with an amino group. May be hydrogenated, but must retain at least one double bond.
Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.
A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.
An essential amino acid that is physiologically active in the L-form.
Single pavement layer of cells which line the luminal surface of the entire vascular system and regulate the transport of macromolecules and blood components.
Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).
The hollow, muscular organ that maintains the circulation of the blood.
A formylated tripeptide originally isolated from bacterial filtrates that is positively chemotactic to polymorphonuclear leucocytes, and causes them to release lysosomal enzymes and become metabolically activated.
Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).
A type C phospholipase with specificity towards PHOSPHATIDYLINOSITOLS that contain INOSITOL 1,4,5-TRISPHOSPHATE. Many of the enzymes listed under this classification are involved in intracellular signaling.
A non-steroidal anti-inflammatory agent (NSAID) that inhibits the enzyme cyclooxygenase necessary for the formation of prostaglandins and other autacoids. It also inhibits the motility of polymorphonuclear leukocytes.
A phorbol ester found in CROTON OIL with very effective tumor promoting activity. It stimulates the synthesis of both DNA and RNA.
Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.
Guanosine 5'-(tetrahydrogen triphosphate). A guanine nucleotide containing three phosphate groups esterified to the sugar moiety.
The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
The giving of drugs, chemicals, or other substances by mouth.
Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.
A phosphodiesterase that specifically cleaves the 3'-phosphate linkage of 2',3'-cyclic nucleotides. It is found at high level in the cytoplasm of cells that form the MYELIN SHEATH.

Luteinizing hormone inhibits conversion of pregnenolone to progesterone in luteal cells from rats on day 19 of pregnancy. (1/2660)

We have previously reported that intrabursal ovarian administration of LH at the end of pregnancy in rats induces a decrease in luteal progesterone (P4) synthesis and an increase in P4 metabolism. However, whether this local luteolytic effect of LH is exerted directly on luteal cells or on other structures, such as follicular or stromal cells, to modify luteal function is unknown. The aim of the present study was to determine the effect of LH on isolated luteal cells obtained on Day 19 of pregnancy. Incubation of luteal cells with 1, 10, 100, or 1000 ng/ml of ovine LH (oLH) for 6 h did not modify basal P4 production. The addition to the culture medium of 22(R)-hydroxycholesterol (22R-HC, 10 microgram/ml), a membrane-permeable P4 precursor, or pregnenolone (10(-2) microM) induced a significant increase in P4 accumulation in the medium in relation to the control value. When luteal cells were preincubated for 2 h with oLH, a significant (p < 0.01) reduction in the 22R-HC- or pregnenolone-stimulated P4 accumulation was observed. Incubation of luteal cells with dibutyryl cAMP (1 mM, a cAMP analogue) plus isobutylmethylxanthine (1 mM, a phosphodiesterase inhibitor) also inhibited pregnenolone-stimulated P4 accumulation. Incubation with an inositol triphosphate synthesis inhibitor, neomycin (1 mM), or an inhibitor of intracellular Ca2+ mobilization, (8,9-N, N-diethylamino)octyl-3,4,5-trimethoxybenzoate (1 mM), did not prevent the decrease in pregnenolone-stimulated P4 secretion induced by oLH. It was concluded that the luteolytic action of LH in late pregnancy is due, at least in part, to a direct action on the luteal cells and that an increase in intracellular cAMP level might mediate this effect.  (+info)

Phosphorylation of the small heat shock-related protein, HSP20, in vascular smooth muscles is associated with changes in the macromolecular associations of HSP20. (2/2660)

Cyclic nucleotide-dependent vasorelaxation is associated with increases in the phosphorylation of a small heat shock-related protein, HSP20. We hypothesized that phosphorylation of HSP20 in vascular smooth muscles is associated with alterations in the macromolecular associations of HSP20. Treatment of bovine carotid artery smooth muscles with the phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine, and the adenylate cyclase activator, forskolin, led to increases in the phosphorylation of HSP20 and dissociation of macromolecular aggregates of HSP20. However, 3-isobutyl-1-methylxanthine and forskolin treatment of a muscle that is uniquely refractory to cyclic nucleotide-dependent vasorelaxation, human umbilical artery smooth muscle, did not result in increases in the phosphorylation of HSP20 or to dissociation of macromolecular aggregates. HSP20 can be phosphorylated in vitro by the catalytic subunit of cAMP-dependent protein kinase (PKA) in both carotid and umbilical arteries and this phosphorylation of HSP20 is associated with dissociation of macromolecular aggregates of HSP20. Activation of cyclic nucleotide-dependent signaling pathways does not lead to changes in the macromolecular associations of another small heat shock protein, HSP27. Interestingly, the myosin light chains (MLC20) are in similar fractions as the HSP20, and phosphorylation of HSP20 is associated with changes in the macromolecular associations of MLC20. These data suggest that increases in the phosphorylation of HSP20 are associated with changes in the macromolecular associations of HSP20. HSP20 may regulate vasorelaxation through a direct interaction with specific contractile regulatory proteins.  (+info)

Identification of a region of the C-terminal domain involved in short-term desensitization of the prostaglandin EP4 receptor. (3/2660)

1. The prostaglandin EP4 receptor, which couples to stimulation of adenylyl cyclase, undergoes rapid agonist-induced desensitization when expressed in CHO-K1 cells. 2. Truncation of the 488-amino acid receptor at residue 350 removes the carboxy-terminal domain and abolishes desensitization. 3. To further delineate residues involved in desensitization, the receptor was truncated at position 408, 383 or 369. Receptors truncated at position 408 or 383 underwent PGE2-induced desensitization, whereas the receptor truncated at position 369 displayed sustained activity, indicating that the essential residues for desensitization lie between 370 and 383. 4. The six serines in the 14-amino acid segment between residues 370 and 383 were mutated to alanine, retaining the entire C-terminal domain. Desensitization was absent in cells expressing this mutant. 5. The results indicate involvement of serines located between 370 and 382 in rapid desensitization of the EP4 receptor.  (+info)

Potency and mechanism of action of E4021, a type 5 phosphodiesterase isozyme-selective inhibitor, on the photoreceptor phosphodiesterase depend on the state of activation of the enzyme. (4/2660)

The ability of inhibitors selective for the type 5 phosphodiesterase isozyme (PDE5) to act on the photoreceptor PDE isozyme (PDE6, the central effector enzyme for visual transduction) is poorly understood. Because PDE5 inhibitors are currently used as therapeutic agents, it is important to assess the potency and mechanism of action of this class of PDE inhibitor on PDE6. We show that E4021 (sodium 1-[6-chloro-4-(3, 4-methylenedioxybenzyl)-aminoquinazolin-2-yl]piperidine-4-ca rboxylate sesquihydrate) inhibits activated PDE6 (KI = 1.7 nM) as potently as PDE5. This makes E4021 the most potent inhibitor of PDE6 discovered to date. The effectiveness of E4021 to inhibit nonactivated PDE6 (with bound inhibitory gamma subunits) is reduced 40-fold compared with the activated enzyme. Furthermore, at intermediate E4021 concentrations and high cGMP concentrations, nonactivated PDE undergoes activation of cGMP hydrolysis rather than inhibition. We demonstrate direct competition of E4021 and the gamma subunits for binding to the catalytic site. Measurements of cGMP binding to noncatalytic regulatory sites on the catalytic subunits of PDE6 rule out an allosteric effect of E4021 by direct binding to these noncatalytic sites. We conclude that E4021 is a competitive inhibitor of cGMP hydrolysis and that the gamma subunit also competes with both E4021 and substrate for catalytic site binding. An understanding of the effects of PDE5-targeted drugs on retinal PDE6 requires a knowledge of the complex interactions among substrate, drug, and inhibitory gamma subunit at the catalytic site of both nonactivated and activated forms of PDE6.  (+info)

Primary biliary cirrhosis associated with membranous glomerulonephritis. (5/2660)

A 33-year-old woman was admitted to our department for evaluation of liver dysfunction and proteinuria. A liver biopsy specimen showed ductular proliferation and moderate portal fibrosis indicating stage II primary biliary cirrhosis. A renal biopsy specimen showed mild to moderate mesangial cell proliferation without crescent formation or interstitial nephritis. Immunofluorescent staining revealed deposition of immunoglobulin G (IgG), third component of complement (C3), and Clq on glomerular basement membranes. The findings indicated stage I membranous glomerulonephritis. Administration of ursodesoxycholic acid together with prednisolone, azathioprine, and dipyridamole decreased proteinuria and improved cholestatic liver dysfunction.  (+info)

NH2-terminal fragments of the 130 kDa subunit of myosin phosphatase increase the Ca2+ sensitivity of porcine renal artery. (6/2660)

1. The effects of the NH2-terminal fragments of M130, a 130 kDa regulatory subunit of smooth muscle myosin phosphatase, on contraction and myosin light chain phosphorylation were investigated in Triton X-100-permeabilized porcine renal artery. 2. Incubation of the permeabilized fibres with M1301-633 (a fragment containing amino acid residues 1-633) or M13044-633 enhanced the Ca2+-induced contraction and shifted the [Ca2+]i-force relationship to the left (EC50 of Ca2+: 330 nM, control, without fragment; 145 nM, M1301-633; 163 nM, M13044-633). Pre-incubation for 1-3 h was needed for these long constructs. 3. M1301-374, M130304-511 and M130297-374, i.e. relatively short constructs compared with M1301-633 and M13044-633, also induced leftward shifts of the [Ca2+]i-force relationship (EC50 of Ca2+: 65 nM, 72 nM and 180 nM, respectively). However, these required no pre-incubation. 4. Deletion of residues 304-374 from the most potent construct, M1301-374, abolished the Ca2+-sensitizing effect. 5. Wortmannin inhibited the enhancement of contraction induced by M130 fragments when added before contraction was initiated and partially inhibited the effects when added after steady-state contraction. 6. M1301-374 slowed the rate of relaxation in Ca2+-free medium. The time for 50 % relaxation with this fragment was 510 +/- 51 s, compared with 274 +/- 14 s for control. 7. The levels of myosin light chain phosphorylation (22.4 %) and force (34. 5 %) obtained with 300 nM Ca2+ were increased by 3 microM M1301-374 to 35.7 and 92.2 %, respectively. However, M1301-374 had no effect on the phosphorylation-force relationship. 8. In conclusion, the NH2-terminal M130 fragments containing residues 304-374 inhibited myosin phosphatase, increased myosin light chain phosphorylation and increased the Ca2+ sensitivity of the contractile apparatus in permeabilized porcine renal artery.  (+info)

Sympathetic neuroeffector transmission in the rat anococcygeus muscle. (7/2660)

1. When intracellular recordings were made from preparations of rat anococcygeus muscle, transmural nerve stimulation evoked noradrenergic excitatory junction potentials (EJPs) made up of two distinct components. Both components were abolished by either guanethidine or alpha-adrenoceptor antagonists, indicating that they resulted from the release of transmitter from sympathetic nerves and the subsequent activation of alpha-adrenoceptors. 2. The first component was associated with a transient increase in the intracellular concentration of calcium ions ([Ca2+]i) and a contraction. Although the second component was often associated with a long lasting increase in [Ca2+]i it was not associated with a contraction unless the second component initiated an action potential. 3. The increase in [Ca2+]i associated with the first component resulted from Ca2+ release from an intracellular store and from entry of Ca2+ through voltage-dependent Ca2+ channels. The increase in [Ca2+]i associated with the second component resulted only from the entry of Ca2+ through L-type Ca2+ channels (CaL channels). The depolarization associated with the initial increase in [Ca2+]i was abolished by reducing the external concentration of chloride ions ([Cl-]o), suggesting that it involved the activation of a Cl- conductance. 4. When the relationships between changes in [Ca2+]i, membrane depolarization and contraction produced by an increasing number of sympathetic nerve stimuli were determined in control, and caffeine- and nifedipine-containing solutions, it was found that an increase in [Ca2+]i recorded in nifedipine produced a larger contraction and larger membrane depolarization than did a similar increase in [Ca2+]i recorded in either control or caffeine-containing solutions. These observations indicate that Ca2+ released from stores more readily triggers contraction and membrane depolarization than does Ca2+ entry via CaL channels.  (+info)

Release of Ca2+ from the sarcoplasmic reticulum increases mitochondrial [Ca2+] in rat pulmonary artery smooth muscle cells. (8/2660)

1. The Ca2+-sensitive fluorescent indicator rhod-2 was used to measure mitochondrial [Ca2+] ([Ca2+]m) in single smooth muscle cells from the rat pulmonary artery, while simultaneously monitoring cytosolic [Ca2+] ([Ca2+]i) with fura-2. 2. Application of caffeine produced an increase in [Ca2+]i and also increased [Ca2+]m. The increase in [Ca2+]m occurred after the increase in [Ca2+]i, and remained elevated for a considerable time after [Ca2+]i had returned to resting values. 3. The protonophore carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP), which causes the mitochondrial membrane potential to collapse, markedly attenuated the increase in [Ca2+]m following caffeine application and also increased the half-time for recovery of [Ca2+]i to resting values. 4. Activation of purinoceptors with ATP also produced increases in both [Ca2+]i and [Ca2+]m in these smooth muscle cells. In some cells, oscillations in [Ca2+]i were observed during ATP application, which produced corresponding oscillations in [Ca2+]m and membrane currents. 5. This study provides direct evidence that Ca2+ release from the sarcoplasmic reticulum, either through ryanodine or inositol 1,4, 5-trisphosphate (InsP3) receptors, increases both cytosolic and mitochondrial [Ca2+] in smooth muscle cells. These results have potential implications both for the role of mitochondria in Ca2+ regulation in smooth muscle, and for understanding how cellular metabolism is regulated.  (+info)

Phosphodiesterase inhibitors (PDE inhibitors) are a class of drugs that work by blocking the action of phosphodiesterase enzymes, which are responsible for breaking down cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), two crucial intracellular signaling molecules.

By inhibiting these enzymes, PDE inhibitors increase the concentration of cAMP and cGMP in the cells, leading to a variety of effects depending on the specific type of PDE enzyme that is inhibited. These drugs have been used in the treatment of various medical conditions such as erectile dysfunction, pulmonary arterial hypertension, and heart failure.

Examples of PDE inhibitors include sildenafil (Viagra), tadalafil (Cialis), vardenafil (Levitra) for erectile dysfunction, and iloprost, treprostinil, and sildenafil for pulmonary arterial hypertension. It's important to note that different PDE inhibitors have varying levels of selectivity for specific PDE isoforms, which can result in different therapeutic effects and side effect profiles.

1-Methyl-3-isobutylxanthine is a chemical compound that belongs to the class of xanthines. It is a methylated derivative of xanthine and is commonly found in some types of tea, coffee, and chocolate. This compound acts as a non-selective phosphodiesterase inhibitor, which means it can increase the levels of intracellular cyclic AMP (cAMP) by preventing its breakdown.

In medical terms, 1-Methyl-3-isobutylxanthine is often used as a bronchodilator and a stimulant of central nervous system. It is also known to have diuretic properties. This compound is sometimes used in the treatment of asthma, COPD (chronic obstructive pulmonary disease), and other respiratory disorders.

It's important to note that 1-Methyl-3-isobutylxanthine can have side effects, including increased heart rate, blood pressure, and anxiety. It should be used under the supervision of a medical professional and its use should be carefully monitored to avoid potential adverse reactions.

3',5'-Cyclic-AMP (cyclic adenosine monophosphate) phosphodiesterases are a group of enzymes that catalyze the breakdown of cyclic AMP to 5'-AMP. These enzymes play a crucial role in regulating the levels of intracellular second messengers, such as cyclic AMP, which are involved in various cellular signaling pathways.

There are several subtypes of phosphodiesterases (PDEs) that specifically target cyclic AMP, including PDE1, PDE2, PDE3, PDE4, PDE7, PDE8, and PDE10. Each subtype has distinct regulatory and catalytic properties, allowing for specific regulation of cyclic AMP levels in different cellular compartments and signaling pathways.

Inhibition of these enzymes can lead to an increase in intracellular cyclic AMP levels, which can have therapeutic effects in various diseases, such as cardiovascular disease, pulmonary hypertension, and central nervous system disorders. Therefore, PDE inhibitors are a valuable class of drugs for the treatment of these conditions.

Rolipram is not a medical term per se, but it is the name of a pharmaceutical compound. Rolipram is a selective inhibitor of phosphodiesterase-4 (PDE4), an enzyme that plays a role in regulating the body's inflammatory response and is involved in various cellular signaling pathways.

Rolipram has been investigated as a potential therapeutic agent for several medical conditions, including depression, asthma, chronic obstructive pulmonary disease (COPD), and Alzheimer's disease. However, its development as a drug has been hindered by issues related to its pharmacokinetics, such as poor bioavailability and a short half-life, as well as side effects like nausea and emesis.

Therefore, while Rolipram is an important compound in the field of pharmacology and has contributed significantly to our understanding of PDE4's role in various physiological processes, it is not typically used as a medical term to describe a specific disease or condition.

Phosphoric diester hydrolases are a class of enzymes that catalyze the hydrolysis of phosphoric diester bonds. These enzymes are also known as phosphatases or nucleotidases. They play important roles in various biological processes, such as signal transduction, metabolism, and regulation of cellular activities.

Phosphoric diester hydrolases can be further classified into several subclasses based on their substrate specificity and catalytic mechanism. For example, alkaline phosphatases (ALPs) are a group of phosphoric diester hydrolases that preferentially hydrolyze phosphomonoester bonds in a variety of organic molecules, releasing phosphate ions and alcohols. On the other hand, nucleotidases are a subclass of phosphoric diester hydrolases that specifically hydrolyze the phosphodiester bonds in nucleotides, releasing nucleosides and phosphate ions.

Overall, phosphoric diester hydrolases are essential for maintaining the balance of various cellular processes by regulating the levels of phosphorylated molecules and nucleotides.

I'm sorry for any confusion, but "Purinones" is not a recognized term in medical terminology. It seems there might be a spelling mistake or a misunderstanding of the term. If you meant "purines," I can provide a definition for that. Purines are heterocyclic aromatic organic compounds that form the basis of several important biomolecules, such as nucleotides and their derivatives found in DNA and RNA. If you had something different in mind, please provide clarification so I can give you an accurate and helpful response.

Cyclic adenosine monophosphate (cAMP) is a key secondary messenger in many biological processes, including the regulation of metabolism, gene expression, and cellular excitability. It is synthesized from adenosine triphosphate (ATP) by the enzyme adenylyl cyclase and is degraded by the enzyme phosphodiesterase.

In the body, cAMP plays a crucial role in mediating the effects of hormones and neurotransmitters on target cells. For example, when a hormone binds to its receptor on the surface of a cell, it can activate a G protein, which in turn activates adenylyl cyclase to produce cAMP. The increased levels of cAMP then activate various effector proteins, such as protein kinases, which go on to regulate various cellular processes.

Overall, the regulation of cAMP levels is critical for maintaining proper cellular function and homeostasis, and abnormalities in cAMP signaling have been implicated in a variety of diseases, including cancer, diabetes, and neurological disorders.

3',5'-Cyclic guanosine monophosphate (cGMP) phosphodiesterases are a group of enzymes that play a role in regulating the levels of cGMP, an important intracellular signaling molecule involved in various biological processes. These enzymes catalyze the hydrolysis of cGMP to 5'-GMP, thereby terminating cGMP-mediated signals within cells.

There are several isoforms of cGMP phosphodiesterases, which differ in their regulatory properties, substrate specificity, and cellular distribution. These enzymes can be activated or inhibited by various factors, including drugs, hormones, and neurotransmitters, and play a crucial role in modulating the activity of cGMP-dependent signaling pathways in different tissues and organs.

Dysregulation of cGMP phosphodiesterase activity has been implicated in various diseases, including cardiovascular disorders, pulmonary hypertension, neurodegenerative diseases, and cancer. Therefore, these enzymes are considered important targets for the development of novel therapeutic strategies for the treatment of these conditions.

Cyclic nucleotide phosphodiesterases (PDEs) are a family of enzymes that regulate intracellular levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which are important second messengers involved in various cellular processes.

Type 4 phosphodiesterases (PDE4) specifically hydrolyze cAMP and play a crucial role in regulating its intracellular concentration. PDE4 is widely expressed in many tissues, including the brain, heart, lungs, and immune system. It is involved in various physiological functions such as smooth muscle relaxation, neurotransmission, and inflammation.

PDE4 inhibitors have been developed as therapeutic agents for a variety of diseases, including asthma, chronic obstructive pulmonary disease (COPD), and depression. These drugs work by increasing intracellular cAMP levels, which can lead to bronchodilation, anti-inflammatory effects, and mood regulation. However, PDE4 inhibitors may also have side effects such as nausea, vomiting, and diarrhea, which limit their clinical use.

Theophylline is a medication that belongs to a class of drugs called methylxanthines. It is used in the management of respiratory diseases such as asthma, chronic obstructive pulmonary disease (COPD), and other conditions that cause narrowing of the airways in the lungs.

Theophylline works by relaxing the smooth muscle around the airways, which helps to open them up and make breathing easier. It also acts as a bronchodilator, increasing the flow of air into and out of the lungs. Additionally, theophylline has anti-inflammatory effects that can help reduce swelling in the airways and relieve symptoms such as coughing, wheezing, and shortness of breath.

Theophylline is available in various forms, including tablets, capsules, and liquid solutions. It is important to take this medication exactly as prescribed by a healthcare provider, as the dosage may vary depending on individual factors such as age, weight, and liver function. Regular monitoring of blood levels of theophylline is also necessary to ensure safe and effective use of the medication.

Phosphodiesterase 3 (PDE3) inhibitors are a class of medications that work by blocking the enzyme phosphodiesterase 3, which is responsible for breaking down cyclic adenosine monophosphate (cAMP) in the body. cAMP is a secondary messenger involved in various cellular processes such as regulation of heart function, vascular smooth muscle relaxation, and metabolism.

By inhibiting PDE3, these medications increase the levels of cAMP in the body, leading to vasodilation (relaxation of blood vessels), positive inotropic effects (improvement of heart contractility), and increased lipolysis (breakdown of fats). As a result, PDE3 inhibitors are used in the treatment of conditions such as heart failure, pulmonary hypertension, and peripheral vascular disease.

Examples of PDE3 inhibitors include cilostazol, milrinone, and enoximone.

Phosphodiesterase 4 inhibitors (PDE4 inhibitors) are a class of drugs that work by increasing the levels of cyclic adenosine monophosphate (cAMP) in cells. They do this by blocking the phosphodiesterase 4 enzyme, which is responsible for breaking down cAMP.

Cyclic AMP is an important intracellular signaling molecule that plays a role in various physiological processes, including inflammation and immune response. By increasing cAMP levels, PDE4 inhibitors can help to reduce inflammation and modulate the immune system.

PDE4 inhibitors have been studied for their potential therapeutic benefits in a range of conditions, including asthma, COPD, psoriasis, atopic dermatitis, and depression. Some examples of PDE4 inhibitors include roflumilast, apremilast, crisaborole, and ditropan.

It's important to note that while PDE4 inhibitors have shown promise in clinical trials, they can also have side effects, such as gastrointestinal symptoms, headache, and dizziness. Additionally, their long-term safety and efficacy are still being studied.

Cyclic guanosine monophosphate (cGMP) is a important second messenger molecule that plays a crucial role in various biological processes within the human body. It is synthesized from guanosine triphosphate (GTP) by the enzyme guanylyl cyclase.

Cyclic GMP is involved in regulating diverse physiological functions, such as smooth muscle relaxation, cardiovascular function, and neurotransmission. It also plays a role in modulating immune responses and cellular growth and differentiation.

In the medical field, changes in cGMP levels or dysregulation of cGMP-dependent pathways have been implicated in various disease states, including pulmonary hypertension, heart failure, erectile dysfunction, and glaucoma. Therefore, pharmacological agents that target cGMP signaling are being developed as potential therapeutic options for these conditions.

Milrinone is a type of medication known as an inotrope and vasodilator. It works by increasing the force of heart muscle contractions and relaxing the blood vessels, which leads to improved pumping ability of the heart and increased blood flow. Milrinone is primarily used in the treatment of heart failure, either in the hospital setting or after discharge, to improve symptoms and help the heart work more efficiently. It is given intravenously (through an IV) and its effects are closely monitored by healthcare professionals due to the potential for serious side effects such as irregular heart rhythms.

Cyclic nucleotide phosphodiesterases (PDEs) are a family of enzymes that regulate intracellular levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which are important second messengers involved in various cellular processes.

Type 3 PDEs, also known as PDE3, are a subtype of this enzyme family that specifically hydrolyze cAMP and cGMP. They are widely expressed in various tissues, including the heart, vascular smooth muscle, platelets, and adipose tissue.

PDE3 plays a crucial role in regulating cardiovascular function, lipolysis, and insulin sensitivity. Inhibition of PDE3 has been shown to have positive inotropic and vasodilatory effects, making it a potential therapeutic target for the treatment of heart failure and pulmonary hypertension. Additionally, PDE3 inhibitors have been used as antiplatelet agents to prevent thrombosis.

There are two isoforms of PDE3, PDE3A and PDE3B, which differ in their tissue distribution and regulatory mechanisms. PDE3A is primarily expressed in the heart and vascular smooth muscle, while PDE3B is found in adipose tissue and insulin-sensitive cells.

Overall, the regulation of intracellular cAMP and cGMP levels by PDE3 plays a critical role in maintaining cardiovascular function, metabolism, and hemostasis.

Phosphodiesterase 5 (PDE5) inhibitors are a class of medications that work by blocking the phosphodiesterase enzyme, specifically PDE5, which is found in the smooth muscle cells lining the blood vessels of the penis. By inhibiting this enzyme, PDE5 inhibitors increase the levels of cyclic guanosine monophosphate (cGMP), a molecule that relaxes these smooth muscles and allows for increased blood flow into the corpus cavernosum of the penis, leading to an erection.

PDE5 inhibitors are commonly used in the treatment of erectile dysfunction (ED) and include medications such as sildenafil (Viagra), tadalafil (Cialis), vardenafil (Levitra), and avanafil (Stendra). These medications are usually taken orally, and their effects can last for several hours. It is important to note that PDE5 inhibitors only work in the presence of sexual stimulation, and they do not increase sexual desire or arousal on their own.

In addition to their use in ED, PDE5 inhibitors have also been shown to be effective in the treatment of pulmonary arterial hypertension (PAH) by relaxing the smooth muscle cells in the blood vessels of the lungs and reducing the workload on the heart.

Papaverine is defined as a smooth muscle relaxant and a non-narcotic alkaloid derived from the opium poppy. It works by blocking the phosphodiesterase enzyme, leading to an increase in cyclic adenosine monophosphate (cAMP) levels within the cells, which in turn results in muscle relaxation.

It is used medically for its vasodilatory effects to treat conditions such as cerebral or peripheral vascular spasms and occlusive diseases, Raynaud's phenomenon, and priapism. Papaverine can also be used as an anti-arrhythmic agent in the management of certain types of cardiac arrhythmias.

It is important to note that papaverine has a narrow therapeutic index, and its use should be closely monitored due to the potential for adverse effects such as hypotension, reflex tachycardia, and gastrointestinal disturbances.

Pyrrolidinones are a class of organic compounds that contain a pyrrolidinone ring, which is a five-membered ring containing four carbon atoms and one nitrogen atom. The nitrogen atom is part of an amide functional group, which consists of a carbonyl (C=O) group bonded to a nitrogen atom.

Pyrrolidinones are commonly found in various natural and synthetic compounds, including pharmaceuticals, agrochemicals, and materials. They exhibit a wide range of biological activities, such as anti-inflammatory, antiviral, and anticancer properties. Some well-known drugs that contain pyrrolidinone rings include the pain reliever tramadol, the muscle relaxant cyclobenzaprine, and the antipsychotic aripiprazole.

Pyrrolidinones can be synthesized through various chemical reactions, such as the cyclization of γ-amino acids or the reaction of α-amino acids with isocyanates. The unique structure and reactivity of pyrrolidinones make them valuable intermediates in organic synthesis and drug discovery.

Cyclic nucleotide phosphodiesterases (PDEs) are a family of enzymes that regulate intracellular levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) by catalyzing the hydrolysis of these second messenger molecules to their inactive forms. These signaling molecules play crucial roles in various cellular processes, including smooth muscle relaxation, cardiac contractility, and neurotransmission.

Type 5 PDEs (PDE5) are a subtype of this enzyme family that specifically hydrolyze cGMP. They are widely distributed in various tissues, including vascular smooth muscle, lung, platelets, and the corpus cavernosum of the penis. PDE5 is particularly important in the regulation of smooth muscle relaxation in the corpus cavernosum, where it plays a key role in the physiological response to sexual stimulation leading to penile erection.

PDE5 inhibitors, such as sildenafil (Viagra), tadalafil (Cialis), and vardenafil (Levitra), are commonly used to treat erectile dysfunction by increasing cGMP levels in the corpus cavernosum, thereby promoting smooth muscle relaxation and enhancing blood flow to the penis. These medications have also been investigated for their potential therapeutic benefits in other conditions, such as pulmonary arterial hypertension and benign prostatic hyperplasia.

Phosphodiesterase I (PDE1) is an enzyme that belongs to the family of phosphodiesterase enzymes, which are responsible for breaking down cyclic nucleotides, such as cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), into their inactive forms. These cyclic nucleotides act as second messengers in various cellular signaling pathways, and their levels are tightly regulated by the balance between synthesis and degradation by enzymes like PDE1.

PDE1 is further classified into three subtypes: PDE1A, PDE1B, and PDE1C. These subtypes have different expression patterns and functions in various tissues and organs. For example, PDE1 is found in the brain, heart, smooth muscle, and other tissues, where it plays a role in regulating vascular tone, neurotransmission, and other physiological processes.

Inhibition of PDE1 has been explored as a potential therapeutic strategy for various conditions, including cardiovascular diseases, neurological disorders, and erectile dysfunction. However, the development of selective and specific PDE1 inhibitors has proven to be challenging due to the high degree of homology among different PDE subtypes.

Cyclic nucleotide phosphodiesterases (PDEs) are a family of enzymes that regulate intracellular levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which are important second messengers involved in various cellular processes.

Type 1 PDEs (PDE1A, PDE1B, PDE1C) are calcium/calmodulin-regulated enzymes that hydrolyze both cAMP and cGMP with similar catalytic efficiency. They play a crucial role in the regulation of vascular smooth muscle contraction, platelet aggregation, and neuronal excitability.

Dysregulation of PDE1 activity has been implicated in various pathological conditions, including hypertension, cardiovascular diseases, and neurological disorders. Therefore, PDE1 inhibitors have emerged as potential therapeutic agents for the treatment of these conditions.

2,3'-Cyclic-nucleotide phosphodiesterases (PDEs) are a subclass of enzymes that belong to the family of phosphodiesterases. These enzymes are responsible for the hydrolysis of 2,3'-cyclic nucleotides, which are cyclic forms of nucleotides that act as second messengers in various cellular signaling pathways.

The two primary types of 2,3'-cyclic nucleotides are 2',3'-cGMP and 2',3'-cAMP, which are produced by the action of certain enzymes on their respective precursors, guanosine triphosphate (GTP) and adenosine triphosphate (ATP). These cyclic nucleotides play important roles in regulating various cellular processes, including metabolism, gene expression, and ion channel activity.

2,3'-Cyclic-nucleotide phosphodiesterases catalyze the hydrolysis of these cyclic nucleotides to their corresponding 5'-monophosphates, thereby terminating their signaling activity. There are several isoforms of 2,3'-cyclic-nucleotide PDEs that have been identified, each with distinct substrate specificities and regulatory properties.

Dysregulation of 2,3'-cyclic-nucleotide PDE activity has been implicated in various diseases, including cancer, cardiovascular disease, and neurological disorders. Therefore, these enzymes have emerged as important targets for the development of therapeutic agents that can modulate their activity and restore normal cellular function.

Colforsin is a drug that belongs to a class of medications called phosphodiesterase inhibitors. It works by increasing the levels of a chemical called cyclic AMP (cyclic adenosine monophosphate) in the body, which helps to relax and widen blood vessels.

Colforsin is not approved for use in humans in many countries, including the United States. However, it has been used in research settings to study its potential effects on heart function and other physiological processes. In animals, colforsin has been shown to have positive inotropic (contractility-enhancing) and lusitropic (relaxation-enhancing) effects on the heart, making it a potential therapeutic option for heart failure and other cardiovascular conditions.

It is important to note that while colforsin has shown promise in preclinical studies, more research is needed to establish its safety and efficacy in humans. Therefore, it should only be used under the supervision of a qualified healthcare professional and in the context of a clinical trial or research study.

Pentoxifylline is a medication that belongs to a class of drugs known as xanthines. Medically, it is defined as a methylxanthine derivative that acts as a vasodilator and improves blood flow by reducing the viscosity of blood. It is used in the treatment of intermittent claudication (pain in the legs due to poor circulation) and may also be used for other conditions that benefit from improved blood flow, such as preventing kidney damage in people with diabetes.

Pentoxifylline works by increasing the flexibility of red blood cells, allowing them to move more easily through narrowed blood vessels, improving oxygen supply to tissues and organs. It also has anti-inflammatory effects that may contribute to its therapeutic benefits.

Common side effects of pentoxifylline include gastrointestinal symptoms like nausea, vomiting, and diarrhea. Less commonly, it can cause dizziness, headache, or skin rashes. Rare but serious side effects include decreased blood pressure, irregular heartbeat, and liver damage. It is essential to follow the prescribing physician's instructions carefully when taking pentoxifylline and report any unusual symptoms promptly.

I apologize for the confusion, but "Bucladesine" is not a recognized medical term or a medication in current use in medicine. It's possible that there may be some mistake or typo in the spelling. If you have any more context about where you encountered this term, I might be able to provide a more accurate and helpful response.

Sulfones are a group of medications that contain a sulfur atom bonded to two oxygen atoms and one other group, typically a hydrogen or carbon atom. They have various medical uses, including as antibacterial, antifungal, and anti-inflammatory agents. One example of a sulfone is dapsone, which is used to treat bacterial infections such as leprosy and Pneumocystis jirovecii pneumonia (PJP), as well as some inflammatory skin conditions. It's important to note that sulfones can have significant side effects and should only be used under the supervision of a healthcare professional.

Xanthines are a type of natural alkaloids that are found in various plants, including tea leaves, cocoa beans, and mate. The most common xanthines are caffeine, theophylline, and theobromine. These compounds have stimulant effects on the central nervous system and are often used in medication to treat conditions such as asthma, bronchitis, and other respiratory issues.

Caffeine is the most widely consumed xanthine and is found in a variety of beverages like coffee, tea, and energy drinks. It works by blocking adenosine receptors in the brain, which can lead to increased alertness and reduced feelings of fatigue.

Theophylline is another xanthine that is used as a bronchodilator to treat asthma and other respiratory conditions. It works by relaxing smooth muscles in the airways, making it easier to breathe.

Theobromine is found in cocoa beans and is responsible for the stimulant effects of chocolate. While it has similar properties to caffeine and theophylline, it is less potent and has a milder effect on the body.

It's worth noting that while xanthines can have beneficial effects when used in moderation, they can also cause negative side effects such as insomnia, nervousness, and rapid heart rate if consumed in large quantities or over an extended period of time.

8-Bromo Cyclic Adenosine Monophosphate (8-Br-cAMP) is a synthetic, cell-permeable analog of cyclic adenosine monophosphate (cAMP). Cyclic AMP is an important second messenger in many signal transduction pathways, and 8-Br-cAMP is often used in research to mimic or study the effects of increased cAMP levels. The bromine atom at the 8-position makes 8-Br-cAMP more resistant to degradation by phosphodiesterases, allowing it to have a longer duration of action compared to cAMP. It is used in various biochemical and cellular studies as a tool compound to investigate the role of cAMP in different signaling pathways.

Cyclic nucleotides are formed by the intramolecular phosphoester bond between the phosphate group and the hydroxyl group at the 3'-carbon atom of the ribose sugar in a nucleotide. This creates a cyclic structure, specifically a cyclic phosphate. The most common cyclic nucleotides are cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). These molecules function as second messengers in cells, playing crucial roles in various cellular signaling pathways related to metabolism, gene expression, and cell differentiation. The levels of cAMP and cGMP are tightly regulated by the activities of enzymes such as adenylate cyclase and guanylate cyclase for their synthesis, and phosphodiesterases for their degradation.

I apologize for any confusion, but "Pyridazines" is not a medical term. It is a chemical term that refers to a class of heterocyclic organic compounds which contain a six-membered ring with two nitrogen atoms. These types of compounds are often used in the synthesis of various pharmaceuticals and agrochemicals, but "Pyridazines" itself is not a medical concept or diagnosis. If you have any questions related to medicine or health, I would be happy to try to help answer those for you.

Adenylate cyclase is an enzyme that catalyzes the conversion of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP). It plays a crucial role in various cellular processes, including signal transduction and metabolism. Adenylate cyclase is activated by hormones and neurotransmitters that bind to G-protein-coupled receptors on the cell membrane, leading to the production of cAMP, which then acts as a second messenger to regulate various intracellular responses. There are several isoforms of adenylate cyclase, each with distinct regulatory properties and subcellular localization.

Purines are heterocyclic aromatic organic compounds that consist of a pyrimidine ring fused to an imidazole ring. They are fundamental components of nucleotides, which are the building blocks of DNA and RNA. In the body, purines can be synthesized endogenously or obtained through dietary sources such as meat, seafood, and certain vegetables.

Once purines are metabolized, they are broken down into uric acid, which is excreted by the kidneys. Elevated levels of uric acid in the body can lead to the formation of uric acid crystals, resulting in conditions such as gout or kidney stones. Therefore, maintaining a balanced intake of purine-rich foods and ensuring proper kidney function are essential for overall health.

Isoproterenol is a medication that belongs to a class of drugs called beta-adrenergic agonists. Medically, it is defined as a synthetic catecholamine with both alpha and beta adrenergic receptor stimulating properties. It is primarily used as a bronchodilator to treat conditions such as asthma and chronic obstructive pulmonary disease (COPD) by relaxing the smooth muscles in the airways, thereby improving breathing.

Isoproterenol can also be used in the treatment of bradycardia (abnormally slow heart rate), cardiac arrest, and heart blocks by increasing the heart rate and contractility. However, due to its non-selective beta-agonist activity, it may cause various side effects such as tremors, palpitations, and increased blood pressure. Its use is now limited due to the availability of more selective and safer medications.

Enoximone is a medication that belongs to a class of drugs called phosphodiesterase inhibitors. It works by increasing the levels of cyclic adenosine monophosphate (cAMP) in the heart, which leads to relaxation of the heart muscle and improved pumping ability. Enoximone is used to treat chronic heart failure and is often given intravenously in a hospital setting.

The medical definition of 'Enoximone' is:

A selective inhibitor of type III phosphodiesterase, which increases the concentration of cyclic adenosine monophosphate (cAMP) in the heart muscle, leading to vasodilation and positive inotropic effects. Enoximone is used in the treatment of congestive heart failure.

Vinca alkaloids are a group of naturally occurring chemicals derived from the Madagascar periwinkle plant, Catharanthus roseus. They are known for their antineoplastic (cancer-fighting) properties and are used in chemotherapy to treat various types of cancer. Some examples of vinca alkaloids include vinblastine, vincristine, and vinorelbine. These agents work by disrupting the normal function of microtubules, which are important components of the cell's structure and play a critical role in cell division. By binding to tubulin, a protein that makes up microtubules, vinca alkaloids prevent the formation of mitotic spindles, which are necessary for cell division. This leads to cell cycle arrest and apoptosis (programmed cell death) in cancer cells. However, vinca alkaloids can also affect normal cells, leading to side effects such as neurotoxicity, myelosuppression, and gastrointestinal disturbances.

Amrinone is a pharmacological agent, specifically a positive inotrope, that is used in the treatment of heart failure. It works by increasing the force of heart muscle contractions and improving cardiac output. Amrinone belongs to a class of drugs called phosphodiesterase inhibitors, which increase cyclic AMP levels in the heart, leading to increased contractility.

Here is the medical definition of 'Amrinone':

Amrinone: A synthetic cardiac drug that acts as a positive inotrope and vasodilator. It works by increasing the force of heart muscle contractions and reducing afterload, which improves cardiac output. Amrinone inhibits phosphodiesterase III, leading to increased intracellular cyclic AMP levels and enhanced calcium sensitivity in myocardial cells. It is used in the treatment of congestive heart failure and is administered intravenously.

Aminophylline is a medication that is used to treat and prevent respiratory symptoms such as bronchospasm, wheezing, and shortness of breath. It is a combination of theophylline and ethylenediamine, and it works by relaxing muscles in the airways and increasing the efficiency of the diaphragm, which makes breathing easier.

Aminophylline is classified as a xanthine derivative and a methylxanthine bronchodilator. It is available in various forms, including tablets, capsules, and liquid solutions, and it is typically taken by mouth two to three times a day. The medication may also be given intravenously in hospital settings for the treatment of acute respiratory distress.

Common side effects of aminophylline include nausea, vomiting, headache, and insomnia. More serious side effects can occur at higher doses and may include irregular heartbeat, seizures, and potentially life-threatening allergic reactions. It is important to follow the dosage instructions carefully and to monitor for any signs of adverse reactions while taking this medication.

'Bufo bufo' is the scientific name for a species of toad commonly known as the common toad or European toad. It belongs to the family Bufonidae and is native to many parts of Europe and western Asia. The toad is typically characterized by its warty skin, large parotoid glands behind its eyes, and a dull yellow or brownish color.

The parotoid glands of Bufo bufo contain a toxic secretion that can be harmful if ingested or comes into contact with mucous membranes, making the toad unpalatable to many predators. The toxin can cause irritation and may lead to respiratory and cardiac problems in some animals, including pets and humans.

While Bufo bufo is not typically aggressive, it will defend itself if threatened by inflating its body, lifting its hind legs, and releasing the toxic secretion from its glands. The common toad is primarily a terrestrial animal but requires access to water for breeding, and it feeds on a variety of small invertebrates such as insects, worms, and slugs.

Cyclic AMP (cAMP)-dependent protein kinases, also known as protein kinase A (PKA), are a family of enzymes that play a crucial role in intracellular signaling pathways. These enzymes are responsible for the regulation of various cellular processes, including metabolism, gene expression, and cell growth and differentiation.

PKA is composed of two regulatory subunits and two catalytic subunits. When cAMP binds to the regulatory subunits, it causes a conformational change that leads to the dissociation of the catalytic subunits. The freed catalytic subunits then phosphorylate specific serine and threonine residues on target proteins, thereby modulating their activity.

The cAMP-dependent protein kinases are activated in response to a variety of extracellular signals, such as hormones and neurotransmitters, that bind to G protein-coupled receptors (GPCRs) or receptor tyrosine kinases (RTKs). These signals lead to the activation of adenylyl cyclase, which catalyzes the conversion of ATP to cAMP. The resulting increase in intracellular cAMP levels triggers the activation of PKA and the downstream phosphorylation of target proteins.

Overall, cAMP-dependent protein kinases are essential regulators of many fundamental cellular processes and play a critical role in maintaining normal physiology and homeostasis. Dysregulation of these enzymes has been implicated in various diseases, including cancer, diabetes, and neurological disorders.

Cyclic nucleotide phosphodiesterases (PDEs) are a family of enzymes that regulate intracellular levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which are important second messengers involved in various cellular processes.

Type 2 phosphodiesterases (PDE2) are a subtype of this family that specifically hydrolyze both cAMP and cGMP to their respective 5'-monophosphates, thereby reducing their intracellular concentrations. PDE2 enzymes are widely expressed in various tissues, including the brain, heart, and vasculature, where they play important roles in regulating signal transduction pathways.

PDE2 enzymes are composed of two regulatory subunits and one catalytic subunit, which contains the active site for phosphodiesterase activity. The regulatory subunits can bind to cGMP, leading to an increase in PDE2 activity towards both cAMP and cGMP. This unique property of PDE2 enzymes allows them to act as coincidence detectors that integrate signals from multiple second messenger pathways.

Inhibition of PDE2 has been shown to have therapeutic potential in various diseases, including cardiovascular disease, neurodegenerative disorders, and cancer. For example, PDE2 inhibitors have been shown to improve cardiac function, protect against ischemic injury, and enhance cognitive function in animal models. However, further research is needed to fully understand the therapeutic potential of PDE2 inhibition and its potential side effects.

A dose-response relationship in the context of drugs refers to the changes in the effects or symptoms that occur as the dose of a drug is increased or decreased. Generally, as the dose of a drug is increased, the severity or intensity of its effects also increases. Conversely, as the dose is decreased, the effects of the drug become less severe or may disappear altogether.

The dose-response relationship is an important concept in pharmacology and toxicology because it helps to establish the safe and effective dosage range for a drug. By understanding how changes in the dose of a drug affect its therapeutic and adverse effects, healthcare providers can optimize treatment plans for their patients while minimizing the risk of harm.

The dose-response relationship is typically depicted as a curve that shows the relationship between the dose of a drug and its effect. The shape of the curve may vary depending on the drug and the specific effect being measured. Some drugs may have a steep dose-response curve, meaning that small changes in the dose can result in large differences in the effect. Other drugs may have a more gradual dose-response curve, where larger changes in the dose are needed to produce significant effects.

In addition to helping establish safe and effective dosages, the dose-response relationship is also used to evaluate the potential therapeutic benefits and risks of new drugs during clinical trials. By systematically testing different doses of a drug in controlled studies, researchers can identify the optimal dosage range for the drug and assess its safety and efficacy.

Photoreceptor cells are specialized neurons in the retina of the eye that convert light into electrical signals. These cells consist of two types: rods and cones. Rods are responsible for vision at low light levels and provide black-and-white, peripheral, and motion sensitivity. Cones are active at higher light levels and are capable of color discrimination and fine detail vision. Both types of photoreceptor cells contain light-sensitive pigments that undergo chemical changes when exposed to light, triggering a series of electrical signals that ultimately reach the brain and contribute to visual perception.

Cyclic nucleotide phosphodiesterases (PDEs) are a family of enzymes that play a crucial role in regulating intracellular levels of cyclic nucleotides, which are important second messengers in various cellular signaling pathways. Among the different types of PDEs, type 6 (PDE6) is specifically expressed in the photoreceptor cells of the retina and is involved in the visual signal transduction cascade.

PDE6 is composed of two catalytic subunits, PDE6α and PDE6β, which are arranged in a heterodimeric complex. These subunits have distinct roles in the enzyme's activity: PDE6α contains the catalytic site that hydrolyzes cyclic guanosine monophosphate (cGMP) to GMP, while PDE6β regulates the activity of PDE6α through its inhibitory γ subunit.

In the visual signal transduction pathway, light stimulation leads to the activation of rhodopsin, which triggers a cascade of events that ultimately results in the hydrolysis of cGMP by PDE6. This reduction in cGMP levels causes the closure of cyclic nucleotide-gated channels in the plasma membrane, leading to hyperpolarization of the photoreceptor cells and the transmission of visual signals to the brain.

Defects in PDE6 have been implicated in various retinal disorders, including congenital stationary night blindness, retinitis pigmentosa, and age-related macular degeneration. Therefore, understanding the structure and function of PDE6 is essential for developing novel therapeutic strategies to treat these vision-threatening diseases.

In the context of medicine and pharmacology, "kinetics" refers to the study of how a drug moves throughout the body, including its absorption, distribution, metabolism, and excretion (often abbreviated as ADME). This field is called "pharmacokinetics."

1. Absorption: This is the process of a drug moving from its site of administration into the bloodstream. Factors such as the route of administration (e.g., oral, intravenous, etc.), formulation, and individual physiological differences can affect absorption.

2. Distribution: Once a drug is in the bloodstream, it gets distributed throughout the body to various tissues and organs. This process is influenced by factors like blood flow, protein binding, and lipid solubility of the drug.

3. Metabolism: Drugs are often chemically modified in the body, typically in the liver, through processes known as metabolism. These changes can lead to the formation of active or inactive metabolites, which may then be further distributed, excreted, or undergo additional metabolic transformations.

4. Excretion: This is the process by which drugs and their metabolites are eliminated from the body, primarily through the kidneys (urine) and the liver (bile).

Understanding the kinetics of a drug is crucial for determining its optimal dosing regimen, potential interactions with other medications or foods, and any necessary adjustments for special populations like pediatric or geriatric patients, or those with impaired renal or hepatic function.

Dibutyryl cyclic guanosine monophosphate (cAMP) is a chemically modified form of the second messenger molecule, cyclic GMP (guanosine monophosphate). The addition of butyryl groups to the cyclic GMP molecule makes it more lipid-soluble and allows for easier passage through cell membranes. This compound is often used in research to activate protein kinases and study the effects of increased intracellular levels of cyclic GMP, which plays a role in various cellular processes such as smooth muscle relaxation, regulation of ion channels, and inhibition of platelet aggregation.

Piperazines are a class of heterocyclic organic compounds that contain a seven-membered ring with two nitrogen atoms at positions 1 and 4. They have the molecular formula N-NRR' where R and R' can be alkyl or aryl groups. Piperazines have a wide range of uses in pharmaceuticals, agrochemicals, and as building blocks in organic synthesis.

In a medical context, piperazines are used in the manufacture of various drugs, including some antipsychotics, antidepressants, antihistamines, and anti-worm medications. For example, the antipsychotic drug trifluoperazine and the antidepressant drug nefazodone both contain a piperazine ring in their chemical structure.

However, it's important to note that some piperazines are also used as recreational drugs due to their stimulant and euphoric effects. These include compounds such as BZP (benzylpiperazine) and TFMPP (trifluoromethylphenylpiperazine), which have been linked to serious health risks, including addiction, seizures, and death. Therefore, the use of these substances should be avoided.

Calcium is an essential mineral that is vital for various physiological processes in the human body. The medical definition of calcium is as follows:

Calcium (Ca2+) is a crucial cation and the most abundant mineral in the human body, with approximately 99% of it found in bones and teeth. It plays a vital role in maintaining structural integrity, nerve impulse transmission, muscle contraction, hormonal secretion, blood coagulation, and enzyme activation.

Calcium homeostasis is tightly regulated through the interplay of several hormones, including parathyroid hormone (PTH), calcitonin, and vitamin D. Dietary calcium intake, absorption, and excretion are also critical factors in maintaining optimal calcium levels in the body.

Hypocalcemia refers to low serum calcium levels, while hypercalcemia indicates high serum calcium levels. Both conditions can have detrimental effects on various organ systems and require medical intervention to correct.

Guanylate cyclase is an enzyme that catalyzes the conversion of guanosine triphosphate (GTP) to cyclic guanosine monophosphate (cGMP), which acts as a second messenger in various cellular signaling pathways. There are two main types of guanylate cyclases: soluble and membrane-bound. Soluble guanylate cyclase is activated by nitric oxide, while membrane-bound guanylate cyclase can be activated by natriuretic peptides. The increased levels of cGMP produced by guanylate cyclase can lead to a variety of cellular responses, including smooth muscle relaxation, neurotransmitter release, and regulation of ion channels. Dysregulation of guanylate cyclase activity has been implicated in several diseases, such as hypertension, heart failure, and cancer.

Dipyridamole is a medication that belongs to a class of drugs called antiplatelet agents. It works by preventing platelets in your blood from sticking together to form clots. Dipyridamole is often used in combination with aspirin to prevent stroke and other complications in people who have had a heart valve replacement or a type of irregular heartbeat called atrial fibrillation.

Dipyridamole can also be used as a stress agent in myocardial perfusion imaging studies, which are tests used to evaluate blood flow to the heart. When used for this purpose, dipyridamole is given intravenously and works by dilating the blood vessels in the heart, allowing more blood to flow through them and making it easier to detect areas of reduced blood flow.

The most common side effects of dipyridamole include headache, dizziness, and gastrointestinal symptoms such as diarrhea, nausea, and vomiting. In rare cases, dipyridamole can cause more serious side effects, such as allergic reactions, abnormal heart rhythms, or low blood pressure. It is important to take dipyridamole exactly as directed by your healthcare provider and to report any unusual symptoms or side effects promptly.

Erectile dysfunction (ED) is the inability to achieve or maintain an erection sufficient for satisfactory sexual performance. It can have physical and psychological causes, such as underlying health conditions like diabetes, heart disease, obesity, and mental health issues like stress, anxiety, and depression. ED can also be a side effect of certain medications. Treatment options include lifestyle changes, medication, counseling, and in some cases, surgery.

Alprostadil is a synthetic form of prostaglandin E1, which is a naturally occurring substance in the body. It is used medically for several purposes, including:

1. Treatment of erectile dysfunction (ED): Alprostadil can be administered directly into the penis as an injection or inserted as a suppository into the urethra to help improve blood flow and achieve an erection.
2. Prevention of closure of a patent ductus arteriosus (PDA) in premature infants: Alprostadil is used to keep the PDA open, allowing for proper blood flow between the pulmonary artery and the aorta, until surgery can be performed.
3. Treatment of peripheral arterial disease: Alprostadil can be administered intravenously to help improve blood flow in patients with peripheral arterial disease.

Alprostadil works by relaxing smooth muscle tissue in blood vessels, which increases blood flow and helps to lower blood pressure. It may also have other effects on the body, such as reducing the risk of blood clots and modulating inflammation.

It is important to note that alprostadil should only be used under the supervision of a healthcare provider, as it can have serious side effects if not used properly.

Phthalazines are not a medical term, but a chemical one. They refer to a class of heterocyclic organic compounds that contain a phthalazine ring in their structure. The phthalazine ring is made up of two benzene rings fused to a single six-membered saturated carbon ring containing two nitrogen atoms.

Phthalazines have no specific medical relevance, but some of their derivatives are used in the pharmaceutical industry as building blocks for various drugs. For example, certain phthalazine derivatives have been developed as potential medications for conditions such as hypertension, heart failure, and cancer. However, these compounds are still in the experimental stages and have not yet been approved for medical use.

It's worth noting that some phthalazines have been found to have toxic effects on living organisms, so their use in medical applications is carefully regulated.

Pyridones are a class of organic compounds that contain a pyridone ring, which is a heterocyclic ring consisting of a six-membered ring with five carbon atoms and one nitrogen atom, with one oxygen atom attached to the nitrogen atom by a double bond. Pyridones can be found in various natural sources, including plants and microorganisms, and they also have important applications in the pharmaceutical industry as building blocks for drug design and synthesis. Some drugs that contain pyridone rings include antihistamines, anti-inflammatory agents, and antiviral agents.

Thionucleotides are chemical compounds that are analogs of nucleotides, which are the building blocks of DNA and RNA. In thionucleotides, one or more of the oxygen atoms in the nucleotide's chemical structure is replaced by a sulfur atom. This modification can affect the way the thionucleotide interacts with other molecules, including enzymes that work with nucleotides and nucleic acids.

Thionucleotides are sometimes used in research to study the biochemistry of nucleic acids and their interactions with other molecules. They can also be used as inhibitors of certain enzymes, such as reverse transcriptase, which is an important target for HIV/AIDS therapy. However, thionucleotides are not normally found in natural biological systems and are not themselves components of DNA or RNA.

Adenosine is a purine nucleoside that is composed of a sugar (ribose) and the base adenine. It plays several important roles in the body, including serving as a precursor for the synthesis of other molecules such as ATP, NAD+, and RNA.

In the medical context, adenosine is perhaps best known for its use as a pharmaceutical agent to treat certain cardiac arrhythmias. When administered intravenously, it can help restore normal sinus rhythm in patients with paroxysmal supraventricular tachycardia (PSVT) by slowing conduction through the atrioventricular node and interrupting the reentry circuit responsible for the arrhythmia.

Adenosine can also be used as a diagnostic tool to help differentiate between narrow-complex tachycardias of supraventricular origin and those that originate from below the ventricles (such as ventricular tachycardia). This is because adenosine will typically terminate PSVT but not affect the rhythm of VT.

It's worth noting that adenosine has a very short half-life, lasting only a few seconds in the bloodstream. This means that its effects are rapidly reversible and generally well-tolerated, although some patients may experience transient symptoms such as flushing, chest pain, or shortness of breath.

Phenylisopropyladenosine (PIA) is not typically defined in the context of medical terminology, but rather it is a term used in pharmacology and biochemistry. PIA is a type of adenosine receptor agonist that specifically binds to and activates the A1 adenosine receptor.

Adenosine receptors are a type of G protein-coupled receptor (GPCR) found in various tissues throughout the body, including the brain, heart, and immune system. Activation of these receptors by agonists like PIA can have diverse effects on cellular function, such as modulating neurotransmission, reducing heart rate and contractility, and regulating inflammation.

While not a medical term per se, PIA is an important compound in the study of adenosine receptor biology and has potential therapeutic applications in various diseases, including neurological disorders, cardiovascular disease, and cancer.

Cyclic nucleotide phosphodiesterases (PDEs) are a family of enzymes that play a crucial role in regulating intracellular levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), which are important second messengers involved in various cellular processes.

Type 7 PDEs, also known as PDE7, is a subtype of the PDE family that specifically hydrolyzes cAMP. PDE7 is primarily expressed in hematopoietic cells, including T lymphocytes, monocytes, and natural killer (NK) cells, and plays a critical role in regulating immune cell functions.

PDE7 has two isoforms, PDE7A and PDE7B, which are encoded by different genes but share similar structures and functions. These isoforms are differentially expressed in various tissues and cells, with PDE7A being more abundant in T lymphocytes and monocytes, while PDE7B is predominantly expressed in NK cells.

Inhibition of PDE7 has been shown to enhance cAMP signaling and modulate immune cell functions, suggesting that PDE7 inhibitors may have therapeutic potential for the treatment of various inflammatory and autoimmune diseases, as well as cancer.

I must clarify that the term "Guinea Pigs" is not typically used in medical definitions. However, in colloquial or informal language, it may refer to people who are used as the first to try out a new medical treatment or drug. This is known as being a "test subject" or "in a clinical trial."

In the field of scientific research, particularly in studies involving animals, guinea pigs are small rodents that are often used as experimental subjects due to their size, cost-effectiveness, and ease of handling. They are not actually pigs from Guinea, despite their name's origins being unclear. However, they do not exactly fit the description of being used in human medical experiments.

Enzyme activation refers to the process by which an enzyme becomes biologically active and capable of carrying out its specific chemical or biological reaction. This is often achieved through various post-translational modifications, such as proteolytic cleavage, phosphorylation, or addition of cofactors or prosthetic groups to the enzyme molecule. These modifications can change the conformation or structure of the enzyme, exposing or creating a binding site for the substrate and allowing the enzymatic reaction to occur.

For example, in the case of proteolytic cleavage, an inactive precursor enzyme, known as a zymogen, is cleaved into its active form by a specific protease. This is seen in enzymes such as trypsin and chymotrypsin, which are initially produced in the pancreas as inactive precursors called trypsinogen and chymotrypsinogen, respectively. Once they reach the small intestine, they are activated by enteropeptidase, a protease that cleaves a specific peptide bond, releasing the active enzyme.

Phosphorylation is another common mechanism of enzyme activation, where a phosphate group is added to a specific serine, threonine, or tyrosine residue on the enzyme by a protein kinase. This modification can alter the conformation of the enzyme and create a binding site for the substrate, allowing the enzymatic reaction to occur.

Enzyme activation is a crucial process in many biological pathways, as it allows for precise control over when and where specific reactions take place. It also provides a mechanism for regulating enzyme activity in response to various signals and stimuli, such as hormones, neurotransmitters, or changes in the intracellular environment.

"Cells, cultured" is a medical term that refers to cells that have been removed from an organism and grown in controlled laboratory conditions outside of the body. This process is called cell culture and it allows scientists to study cells in a more controlled and accessible environment than they would have inside the body. Cultured cells can be derived from a variety of sources, including tissues, organs, or fluids from humans, animals, or cell lines that have been previously established in the laboratory.

Cell culture involves several steps, including isolation of the cells from the tissue, purification and characterization of the cells, and maintenance of the cells in appropriate growth conditions. The cells are typically grown in specialized media that contain nutrients, growth factors, and other components necessary for their survival and proliferation. Cultured cells can be used for a variety of purposes, including basic research, drug development and testing, and production of biological products such as vaccines and gene therapies.

It is important to note that cultured cells may behave differently than they do in the body, and results obtained from cell culture studies may not always translate directly to human physiology or disease. Therefore, it is essential to validate findings from cell culture experiments using additional models and ultimately in clinical trials involving human subjects.

Prostaglandin I (PGI) is a type of prostaglandin, which is a group of lipid compounds that are synthesized in the body from fatty acids and have various hormonal-like effects in the body. Specifically, PGI is also known as prostacyclin, and it is primarily produced by the endothelial cells that line the interior surface of blood vessels.

PGI has several important functions in the body, including:

1. Vasodilation: PGI causes blood vessels to dilate or widen, which helps to lower blood pressure and improve blood flow.
2. Inhibition of platelet aggregation: PGI inhibits the aggregation or clumping together of platelets in the blood, which helps to prevent blood clots from forming.
3. Anti-inflammatory effects: PGI has anti-inflammatory effects and can help to reduce inflammation in the body.

PGI is synthesized from arachidonic acid, a fatty acid that is released from cell membranes by the action of enzymes called phospholipases. Once arachidonic acid is released, it is converted into prostaglandin H2 (PGH2) by an enzyme called cyclooxygenase (COX). PGH2 is then further metabolized into PGI by the action of another enzyme called prostacyclin synthase.

PGI is rapidly broken down in the body and has a short half-life, which means that its effects are usually localized to the site where it is produced. However, abnormalities in PGI synthesis or activity have been implicated in several diseases, including pulmonary hypertension, atherosclerosis, and cancer.

Penile erection is a physiological response that involves the engagement of the corpus cavernosum and spongiosum (erectile tissue) of the penis with blood, leading to its stiffness and rigidity. This process is primarily regulated by the autonomic nervous system and is influenced by factors such as sexual arousal, emotional state, and certain medications or medical conditions. A penile erection may also occur in non-sexual situations, such as during sleep (nocturnal penile tumescence) or due to other physical stimuli.

Cyclic guanosine monophosphate (cGMP)-dependent protein kinases (PKGs) are a type of enzyme that add phosphate groups to other proteins, thereby modifying their function. These kinases are activated by cGMP, which is a second messenger molecule that helps transmit signals within cells. PKGs play important roles in various cellular processes, including smooth muscle relaxation, platelet aggregation, and cardiac contractility. They have been implicated in the regulation of a number of physiological functions, such as blood flow, inflammation, and learning and memory. There are two main isoforms of cGMP-dependent protein kinases, PKG I and PKG II, which differ in their tissue distribution, regulatory properties, and substrate specificity.

Second messenger systems are a type of intracellular signaling pathway that allows cells to respond to external signals, such as hormones and neurotransmitters. When an extracellular signal binds to a specific receptor on the cell membrane, it activates a G-protein or an enzyme associated with the receptor. This activation leads to the production of a second messenger molecule inside the cell, which then propagates the signal and triggers various intracellular responses.

Examples of second messengers include cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP), inositol trisphosphate (IP3), diacylglycerol (DAG), and calcium ions (Ca2+). These second messengers activate or inhibit various downstream effectors, such as protein kinases, ion channels, and gene transcription factors, leading to changes in cellular functions, such as metabolism, gene expression, cell growth, differentiation, and apoptosis.

Second messenger systems play crucial roles in many physiological processes, including sensory perception, neurotransmission, hormonal regulation, immune response, and development. Dysregulation of these systems can contribute to various diseases, such as cancer, diabetes, cardiovascular disease, and neurological disorders.

A chemical stimulation in a medical context refers to the process of activating or enhancing physiological or psychological responses in the body using chemical substances. These chemicals can interact with receptors on cells to trigger specific reactions, such as neurotransmitters and hormones that transmit signals within the nervous system and endocrine system.

Examples of chemical stimulation include the use of medications, drugs, or supplements that affect mood, alertness, pain perception, or other bodily functions. For instance, caffeine can chemically stimulate the central nervous system to increase alertness and decrease feelings of fatigue. Similarly, certain painkillers can chemically stimulate opioid receptors in the brain to reduce the perception of pain.

It's important to note that while chemical stimulation can have therapeutic benefits, it can also have adverse effects if used improperly or in excessive amounts. Therefore, it's essential to follow proper dosing instructions and consult with a healthcare provider before using any chemical substances for stimulation purposes.

Isoquinolines are not a medical term per se, but a chemical classification. They refer to a class of organic compounds that consist of a benzene ring fused to a piperidine ring. This structure is similar to that of quinoline, but with the nitrogen atom located at a different position in the ring.

Isoquinolines have various biological activities and can be found in some natural products, including certain alkaloids. Some isoquinoline derivatives have been developed as drugs for the treatment of various conditions, such as cardiovascular diseases, neurological disorders, and cancer. However, specific medical definitions related to isoquinolines typically refer to the use or effects of these specific drugs rather than the broader class of compounds.

Nitric oxide (NO) is a molecule made up of one nitrogen atom and one oxygen atom. In the body, it is a crucial signaling molecule involved in various physiological processes such as vasodilation, immune response, neurotransmission, and inhibition of platelet aggregation. It is produced naturally by the enzyme nitric oxide synthase (NOS) from the amino acid L-arginine. Inhaled nitric oxide is used medically to treat pulmonary hypertension in newborns and adults, as it helps to relax and widen blood vessels, improving oxygenation and blood flow.

Prostaglandins E, Synthetic are a class of medications that mimic the effects of natural prostaglandins, which are hormone-like substances involved in various bodily functions, including inflammation, pain perception, and regulation of the female reproductive system. Prostaglandin E1 (PGE1) is one of the most commonly synthesized prostaglandins used in medical treatments.

Synthetic prostaglandins E are often used for their vasodilatory effects, which help to improve blood flow and reduce blood pressure. They may also be used to prevent or treat blood clots, as well as to manage certain conditions related to the female reproductive system, such as inducing labor or causing an abortion.

Some examples of synthetic prostaglandins E include misoprostol (Cytotec), dinoprostone (Cervidil, Prepidil), and alprostadil (Edex, Caverject). These medications are available in various forms, such as tablets, suppositories, or injectable solutions, and their use depends on the specific medical condition being treated.

It is important to note that synthetic prostaglandins E can have significant side effects, including gastrointestinal symptoms (such as diarrhea, nausea, and vomiting), abdominal pain, and uterine contractions. Therefore, they should only be used under the close supervision of a healthcare provider.

Vasodilator agents are pharmacological substances that cause the relaxation or widening of blood vessels by relaxing the smooth muscle in the vessel walls. This results in an increase in the diameter of the blood vessels, which decreases vascular resistance and ultimately reduces blood pressure. Vasodilators can be further classified based on their site of action:

1. Systemic vasodilators: These agents cause a generalized relaxation of the smooth muscle in the walls of both arteries and veins, resulting in a decrease in peripheral vascular resistance and preload (the volume of blood returning to the heart). Examples include nitroglycerin, hydralazine, and calcium channel blockers.
2. Arterial vasodilators: These agents primarily affect the smooth muscle in arterial vessel walls, leading to a reduction in afterload (the pressure against which the heart pumps blood). Examples include angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and direct vasodilators like sodium nitroprusside.
3. Venous vasodilators: These agents primarily affect the smooth muscle in venous vessel walls, increasing venous capacitance and reducing preload. Examples include nitroglycerin and other organic nitrates.

Vasodilator agents are used to treat various cardiovascular conditions such as hypertension, heart failure, angina, and pulmonary arterial hypertension. It is essential to monitor their use carefully, as excessive vasodilation can lead to orthostatic hypotension, reflex tachycardia, or fluid retention.

Transducin is a G protein found in the rod cells of the retina and plays a crucial role in the visual signal transduction pathway. It is responsible for converting the light-induced isomerization of rhodopsin into a biochemical signal, which ultimately leads to the activation of downstream effectors and the generation of a neural response.

Transducin has three subunits: alpha (Tα), beta (Tβ), and gamma (Tγ). When light activates rhodopsin, it interacts with the Tα subunit, causing it to exchange GDP for GTP and dissociate from the Tβγ complex. The activated Tα then interacts with a downstream effector called phosphodiesterase (PDE), which leads to the hydrolysis of cGMP and the closure of cGMP-gated ion channels in the plasma membrane. This results in the hyperpolarization of the rod cell, which is the initial step in the visual signal transduction pathway.

Overall, transducin is a key player in the conversion of light energy into neural signals, allowing us to see and perceive our visual world.

"Inbred strains of rats" are genetically identical rodents that have been produced through many generations of brother-sister mating. This results in a high degree of homozygosity, where the genes at any particular locus in the genome are identical in all members of the strain.

Inbred strains of rats are widely used in biomedical research because they provide a consistent and reproducible genetic background for studying various biological phenomena, including the effects of drugs, environmental factors, and genetic mutations on health and disease. Additionally, inbred strains can be used to create genetically modified models of human diseases by introducing specific mutations into their genomes.

Some commonly used inbred strains of rats include the Wistar Kyoto (WKY), Sprague-Dawley (SD), and Fischer 344 (F344) rat strains. Each strain has its own unique genetic characteristics, making them suitable for different types of research.

nitroprusside (ni-troe-rus-ide)

A rapid-acting vasodilator used in the management of severe hypertension, acute heart failure, and to reduce afterload in patients undergoing cardiac surgery. It is a potent arterial and venous dilator that decreases preload and afterload, thereby reducing myocardial oxygen demand. Nitroprusside is metabolized to cyanide, which must be monitored closely during therapy to prevent toxicity.

Pharmacologic class: Peripheral vasodilators

Therapeutic class: Antihypertensives, Vasodilators

Medical Categories: Cardiovascular Drugs, Hypertension Agents

Tetrazoles are a class of heterocyclic aromatic organic compounds that contain a five-membered ring with four nitrogen atoms and one carbon atom. They have the chemical formula of C2H2N4. Tetrazoles are stable under normal conditions, but can decompose explosively when heated or subjected to strong shock.

In the context of medicinal chemistry, tetrazoles are sometimes used as bioisosteres for carboxylic acids, as they can mimic some of their chemical and biological properties. This has led to the development of several drugs that contain tetrazole rings, such as the antiviral drug tenofovir and the anti-inflammatory drug celecoxib.

However, it's important to note that 'tetrazoles' is not a medical term per se, but rather a chemical term that can be used in the context of medicinal chemistry or pharmacology.

"Cattle" is a term used in the agricultural and veterinary fields to refer to domesticated animals of the genus *Bos*, primarily *Bos taurus* (European cattle) and *Bos indicus* (Zebu). These animals are often raised for meat, milk, leather, and labor. They are also known as bovines or cows (for females), bulls (intact males), and steers/bullocks (castrated males). However, in a strict medical definition, "cattle" does not apply to humans or other animals.

Imidazoles are a class of heterocyclic organic compounds that contain a double-bonded nitrogen atom and two additional nitrogen atoms in the ring. They have the chemical formula C3H4N2. In a medical context, imidazoles are commonly used as antifungal agents. Some examples of imidazole-derived antifungals include clotrimazole, miconazole, and ketoconazole. These medications work by inhibiting the synthesis of ergosterol, a key component of fungal cell membranes, leading to increased permeability and death of the fungal cells. Imidazoles may also have anti-inflammatory, antibacterial, and anticancer properties.

Cholera toxin is a protein toxin produced by the bacterium Vibrio cholerae, which causes the infectious disease cholera. The toxin is composed of two subunits, A and B, and its primary mechanism of action is to alter the normal function of cells in the small intestine.

The B subunit of the toxin binds to ganglioside receptors on the surface of intestinal epithelial cells, allowing the A subunit to enter the cell. Once inside, the A subunit activates a signaling pathway that results in the excessive secretion of chloride ions and water into the intestinal lumen, leading to profuse, watery diarrhea, dehydration, and other symptoms associated with cholera.

Cholera toxin is also used as a research tool in molecular biology and immunology due to its ability to modulate cell signaling pathways. It has been used to study the mechanisms of signal transduction, protein trafficking, and immune responses.

Niacin, also known as nicotinic acid, is a form of vitamin B3 (B-complex vitamin) that is used by the body to turn food into energy. It is found in various foods including meat, fish, milk, eggs, green vegetables, and cereal grains. Niacin is also available as a dietary supplement and prescription medication.

As a medication, niacin is primarily used to treat high cholesterol levels. It works by reducing the production of LDL (bad) cholesterol in the body and increasing the levels of HDL (good) cholesterol. Niacin can also help lower triglycerides, another type of fat found in the blood.

Niacin is available in immediate-release, sustained-release, and extended-release forms. The immediate-release form can cause flushing of the skin, itching, tingling, and headaches, which can be uncomfortable but are not usually serious. The sustained-release and extended-release forms may have fewer side effects, but they can also increase the risk of liver damage and other serious side effects.

It is important to note that niacin should only be taken under the supervision of a healthcare provider, as it can interact with other medications and have potentially serious side effects.

Iloprost is a synthetic analogue of prostacyclin, a naturally occurring substance in the body. It is a medication that belongs to a class of drugs called vasodilators, which work by relaxing and widening blood vessels. Iloprost is used to treat pulmonary arterial hypertension (PAH), a condition characterized by high blood pressure in the arteries that supply blood to the lungs. By dilating these blood vessels, iloprost helps reduce the workload on the heart and improve symptoms associated with PAH such as shortness of breath, fatigue, and dizziness.

Iloprost is administered through inhalation using a nebulizer, typically several times a day. It may also be used to prevent or treat episodes of digital ischemia, a condition that causes reduced blood flow to the fingers and toes, leading to pain and tissue damage.

It's important to note that while iloprost can help manage symptoms of PAH and digital ischemia, it does not cure these conditions. Close monitoring by a healthcare provider is necessary to ensure safe and effective use of this medication.

Isoenzymes, also known as isoforms, are multiple forms of an enzyme that catalyze the same chemical reaction but differ in their amino acid sequence, structure, and/or kinetic properties. They are encoded by different genes or alternative splicing of the same gene. Isoenzymes can be found in various tissues and organs, and they play a crucial role in biological processes such as metabolism, detoxification, and cell signaling. Measurement of isoenzyme levels in body fluids (such as blood) can provide valuable diagnostic information for certain medical conditions, including tissue damage, inflammation, and various diseases.

A rod cell outer segment is a specialized structure in the retina of the eye that is responsible for photoreception, or the conversion of light into electrical signals. Rod cells are one of the two types of photoreceptor cells in the retina, with the other type being cone cells. Rod cells are more sensitive to light than cone cells and are responsible for low-light vision and peripheral vision.

The outer segment of a rod cell is a long, thin structure that contains stacks of discs filled with the visual pigment rhodopsin. When light hits the rhodopsin molecules in the discs, it causes a chemical reaction that leads to the activation of a signaling pathway within the rod cell. This ultimately results in the generation of an electrical signal that is transmitted to the brain via the optic nerve.

The outer segment of a rod cell is constantly being regenerated and broken down through a process called shedding and renewal. The tips of the outer segments are shed and phagocytosed by cells called retinal pigment epithelial (RPE) cells, which help to maintain the health and function of the rod cells.

Adrenergic receptors are a type of G protein-coupled receptor that binds and responds to catecholamines, such as epinephrine (adrenaline) and norepinephrine (noradrenaline). Beta adrenergic receptors (β-adrenergic receptors) are a subtype of adrenergic receptors that include three distinct subclasses: β1, β2, and β3. These receptors are widely distributed throughout the body and play important roles in various physiological functions, including cardiovascular regulation, bronchodilation, lipolysis, and glucose metabolism.

β1-adrenergic receptors are primarily located in the heart and regulate cardiac contractility, chronotropy (heart rate), and relaxation. β2-adrenergic receptors are found in various tissues, including the lungs, vascular smooth muscle, liver, and skeletal muscle. They mediate bronchodilation, vasodilation, glycogenolysis, and lipolysis. β3-adrenergic receptors are mainly expressed in adipose tissue, where they stimulate lipolysis and thermogenesis.

Agonists of β-adrenergic receptors include catecholamines like epinephrine and norepinephrine, as well as synthetic drugs such as dobutamine (a β1-selective agonist) and albuterol (a non-selective β2-agonist). Antagonists of β-adrenergic receptors are commonly used in the treatment of various conditions, including hypertension, angina pectoris, heart failure, and asthma. Examples of β-blockers include metoprolol (a β1-selective antagonist) and carvedilol (a non-selective β-blocker with additional α1-adrenergic receptor blocking activity).

Triazines are not a medical term, but a class of chemical compounds. They have a six-membered ring containing three nitrogen atoms and three carbon atoms. Some triazine derivatives are used in medicine as herbicides, antimicrobials, and antitumor agents.

Oxadiazoles are heterocyclic compounds containing a five-membered ring consisting of two carbon atoms, one nitrogen atom, and two oxygen atoms in an alternating sequence. There are three possible isomers of oxadiazole, depending on the position of the nitrogen atom: 1,2,3-oxadiazole, 1,2,4-oxadiazole, and 1,3,4-oxadiazole. These compounds have significant interest in medicinal chemistry due to their diverse biological activities, including anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer properties. Some oxadiazoles also exhibit potential as contrast agents for medical imaging techniques such as magnetic resonance imaging (MRI) and computed tomography (CT).

Adrenergic beta-agonists are a class of medications that bind to and activate beta-adrenergic receptors, which are found in various tissues throughout the body. These receptors are part of the sympathetic nervous system and mediate the effects of the neurotransmitter norepinephrine (also called noradrenaline) and the hormone epinephrine (also called adrenaline).

When beta-agonists bind to these receptors, they stimulate a range of physiological responses, including relaxation of smooth muscle in the airways, increased heart rate and contractility, and increased metabolic rate. As a result, adrenergic beta-agonists are often used to treat conditions such as asthma, chronic obstructive pulmonary disease (COPD), and bronchitis, as they can help to dilate the airways and improve breathing.

There are several different types of beta-agonists, including short-acting and long-acting formulations. Short-acting beta-agonists (SABAs) are typically used for quick relief of symptoms, while long-acting beta-agonists (LABAs) are used for more sustained symptom control. Examples of adrenergic beta-agonists include albuterol (also known as salbutamol), terbutaline, formoterol, and salmeterol.

It's worth noting that while adrenergic beta-agonists can be very effective in treating respiratory conditions, they can also have side effects, particularly if used in high doses or for prolonged periods of time. These may include tremors, anxiety, palpitations, and increased blood pressure. As with any medication, it's important to use adrenergic beta-agonists only as directed by a healthcare professional.

Enzyme inhibitors are substances that bind to an enzyme and decrease its activity, preventing it from catalyzing a chemical reaction in the body. They can work by several mechanisms, including blocking the active site where the substrate binds, or binding to another site on the enzyme to change its shape and prevent substrate binding. Enzyme inhibitors are often used as drugs to treat various medical conditions, such as high blood pressure, abnormal heart rhythms, and bacterial infections. They can also be found naturally in some foods and plants, and can be used in research to understand enzyme function and regulation.

"Wistar rats" are a strain of albino rats that are widely used in laboratory research. They were developed at the Wistar Institute in Philadelphia, USA, and were first introduced in 1906. Wistar rats are outbred, which means that they are genetically diverse and do not have a fixed set of genetic characteristics like inbred strains.

Wistar rats are commonly used as animal models in biomedical research because of their size, ease of handling, and relatively low cost. They are used in a wide range of research areas, including toxicology, pharmacology, nutrition, cancer, cardiovascular disease, and behavioral studies. Wistar rats are also used in safety testing of drugs, medical devices, and other products.

Wistar rats are typically larger than many other rat strains, with males weighing between 500-700 grams and females weighing between 250-350 grams. They have a lifespan of approximately 2-3 years. Wistar rats are also known for their docile and friendly nature, making them easy to handle and work with in the laboratory setting.

Caffeine is a central nervous system stimulant that occurs naturally in the leaves, seeds, or fruits of some plants. It can also be produced artificially and added to various products, such as food, drinks, and medications. Caffeine has a number of effects on the body, including increasing alertness, improving mood, and boosting energy levels.

In small doses, caffeine is generally considered safe for most people. However, consuming large amounts of caffeine can lead to negative side effects, such as restlessness, insomnia, rapid heart rate, and increased blood pressure. It is also possible to become dependent on caffeine, and withdrawal symptoms can occur if consumption is suddenly stopped.

Caffeine is found in a variety of products, including coffee, tea, chocolate, energy drinks, and some medications. The amount of caffeine in these products can vary widely, so it is important to pay attention to serving sizes and labels to avoid consuming too much.

Atrial natriuretic factor (ANF), also known as atrial natriuretic peptide (ANP), is a hormone that is primarily produced and secreted by the atria of the heart in response to stretching of the cardiac muscle cells due to increased blood volume. ANF plays a crucial role in regulating body fluid homeostasis, blood pressure, and cardiovascular function.

The main physiological action of ANF is to promote sodium and water excretion by the kidneys, which helps lower blood volume and reduce blood pressure. ANF also relaxes vascular smooth muscle, dilates blood vessels, and inhibits the renin-angiotensin-aldosterone system (RAAS), further contributing to its blood pressure-lowering effects.

Defects in ANF production or action have been implicated in several cardiovascular disorders, including heart failure, hypertension, and kidney disease. Therefore, ANF and its analogs are being investigated as potential therapeutic agents for the treatment of these conditions.

Propranolol is a medication that belongs to a class of drugs called beta blockers. Medically, it is defined as a non-selective beta blocker, which means it blocks the effects of both epinephrine (adrenaline) and norepinephrine (noradrenaline) on the heart and other organs. These effects include reducing heart rate, contractility, and conduction velocity, leading to decreased oxygen demand by the myocardium. Propranolol is used in the management of various conditions such as hypertension, angina pectoris, arrhythmias, essential tremor, anxiety disorders, and infants with congenital heart defects. It may also be used to prevent migraines and reduce the risk of future heart attacks. As with any medication, it should be taken under the supervision of a healthcare provider due to potential side effects and contraindications.

Smooth muscle, also known as involuntary muscle, is a type of muscle that is controlled by the autonomic nervous system and functions without conscious effort. These muscles are found in the walls of hollow organs such as the stomach, intestines, bladder, and blood vessels, as well as in the eyes, skin, and other areas of the body.

Smooth muscle fibers are shorter and narrower than skeletal muscle fibers and do not have striations or sarcomeres, which give skeletal muscle its striped appearance. Smooth muscle is controlled by the autonomic nervous system through the release of neurotransmitters such as acetylcholine and norepinephrine, which bind to receptors on the smooth muscle cells and cause them to contract or relax.

Smooth muscle plays an important role in many physiological processes, including digestion, circulation, respiration, and elimination. It can also contribute to various medical conditions, such as hypertension, gastrointestinal disorders, and genitourinary dysfunction, when it becomes overactive or underactive.

Cardiotonic agents are a type of medication that have a positive inotropic effect on the heart, meaning they help to improve the contractility and strength of heart muscle contractions. These medications are often used to treat heart failure, as they can help to improve the efficiency of the heart's pumping ability and increase cardiac output.

Cardiotonic agents work by increasing the levels of calcium ions inside heart muscle cells during each heartbeat, which in turn enhances the force of contraction. Some common examples of cardiotonic agents include digitalis glycosides (such as digoxin), which are derived from the foxglove plant, and synthetic medications such as dobutamine and milrinone.

While cardiotonic agents can be effective in improving heart function, they can also have potentially serious side effects, including arrhythmias, electrolyte imbalances, and digestive symptoms. As a result, they are typically used under close medical supervision and their dosages may need to be carefully monitored to minimize the risk of adverse effects.

Drug synergism is a pharmacological concept that refers to the interaction between two or more drugs, where the combined effect of the drugs is greater than the sum of their individual effects. This means that when these drugs are administered together, they produce an enhanced therapeutic response compared to when they are given separately.

Drug synergism can occur through various mechanisms, such as:

1. Pharmacodynamic synergism - When two or more drugs interact with the same target site in the body and enhance each other's effects.
2. Pharmacokinetic synergism - When one drug affects the metabolism, absorption, distribution, or excretion of another drug, leading to an increased concentration of the second drug in the body and enhanced therapeutic effect.
3. Physiochemical synergism - When two drugs interact physically, such as when one drug enhances the solubility or permeability of another drug, leading to improved absorption and bioavailability.

It is important to note that while drug synergism can result in enhanced therapeutic effects, it can also increase the risk of adverse reactions and toxicity. Therefore, healthcare providers must carefully consider the potential benefits and risks when prescribing combinations of drugs with known or potential synergistic effects.

Signal transduction is the process by which a cell converts an extracellular signal, such as a hormone or neurotransmitter, into an intracellular response. This involves a series of molecular events that transmit the signal from the cell surface to the interior of the cell, ultimately resulting in changes in gene expression, protein activity, or metabolism.

The process typically begins with the binding of the extracellular signal to a receptor located on the cell membrane. This binding event activates the receptor, which then triggers a cascade of intracellular signaling molecules, such as second messengers, protein kinases, and ion channels. These molecules amplify and propagate the signal, ultimately leading to the activation or inhibition of specific cellular responses.

Signal transduction pathways are highly regulated and can be modulated by various factors, including other signaling molecules, post-translational modifications, and feedback mechanisms. Dysregulation of these pathways has been implicated in a variety of diseases, including cancer, diabetes, and neurological disorders.

Prostaglandin E (PGE) is a type of prostaglandin, which is a group of lipid compounds that are synthesized in the body from fatty acids and have diverse hormone-like effects. Prostaglandins are not actually hormones, but are similar to them in that they act as chemical messengers that have specific effects on certain cells.

Prostaglandin E is one of the most abundant prostaglandins in the body and has a variety of physiological functions. It is involved in the regulation of inflammation, pain perception, fever, and smooth muscle contraction. Prostaglandin E also plays a role in the regulation of blood flow, platelet aggregation, and gastric acid secretion.

Prostaglandin E is synthesized from arachidonic acid, which is released from cell membranes by the action of enzymes called phospholipases. Once formed, prostaglandin E binds to specific receptors on the surface of cells, leading to a variety of intracellular signaling events that ultimately result in changes in cell behavior.

Prostaglandin E is used medically in the treatment of several conditions, including dysmenorrhea (painful menstruation), postpartum hemorrhage, and patent ductus arteriosus (a congenital heart defect). It is also used as a diagnostic tool in the evaluation of kidney function.

Sprague-Dawley rats are a strain of albino laboratory rats that are widely used in scientific research. They were first developed by researchers H.H. Sprague and R.C. Dawley in the early 20th century, and have since become one of the most commonly used rat strains in biomedical research due to their relatively large size, ease of handling, and consistent genetic background.

Sprague-Dawley rats are outbred, which means that they are genetically diverse and do not suffer from the same limitations as inbred strains, which can have reduced fertility and increased susceptibility to certain diseases. They are also characterized by their docile nature and low levels of aggression, making them easier to handle and study than some other rat strains.

These rats are used in a wide variety of research areas, including toxicology, pharmacology, nutrition, cancer, and behavioral studies. Because they are genetically diverse, Sprague-Dawley rats can be used to model a range of human diseases and conditions, making them an important tool in the development of new drugs and therapies.

In the field of medicine, "time factors" refer to the duration of symptoms or time elapsed since the onset of a medical condition, which can have significant implications for diagnosis and treatment. Understanding time factors is crucial in determining the progression of a disease, evaluating the effectiveness of treatments, and making critical decisions regarding patient care.

For example, in stroke management, "time is brain," meaning that rapid intervention within a specific time frame (usually within 4.5 hours) is essential to administering tissue plasminogen activator (tPA), a clot-busting drug that can minimize brain damage and improve patient outcomes. Similarly, in trauma care, the "golden hour" concept emphasizes the importance of providing definitive care within the first 60 minutes after injury to increase survival rates and reduce morbidity.

Time factors also play a role in monitoring the progression of chronic conditions like diabetes or heart disease, where regular follow-ups and assessments help determine appropriate treatment adjustments and prevent complications. In infectious diseases, time factors are crucial for initiating antibiotic therapy and identifying potential outbreaks to control their spread.

Overall, "time factors" encompass the significance of recognizing and acting promptly in various medical scenarios to optimize patient outcomes and provide effective care.

Naphthyridines are a class of heterocyclic organic compounds that contain a naphthyridine core structure, which is a polycyclic aromatic hydrocarbon made up of two benzene rings fused to a tetrahydropyridine ring. They have a variety of pharmacological activities and are used in the development of various therapeutic agents, including antibiotics, antivirals, and anticancer drugs.

In medical terms, naphthyridines do not have a specific clinical definition or application, but they are rather a chemical class that is utilized in the design and synthesis of drugs with potential therapeutic benefits. The unique structure and properties of naphthyridines make them attractive candidates for drug development, particularly in areas where new treatments are needed to overcome drug resistance or improve efficacy.

It's worth noting that while naphthyridines have shown promise in preclinical studies, further research is needed to fully understand their safety and effectiveness in humans before they can be approved as therapeutic agents.

Methylene Blue is a heterocyclic aromatic organic compound with the molecular formula C16H18ClN3S. It is primarily used as a medication, but can also be used as a dye or as a chemical reagent. As a medication, it is used in the treatment of methemoglobinemia (a condition where an abnormal amount of methemoglobin is present in the blood), as well as in some forms of poisoning and infections. It works by acting as a reducing agent, converting methemoglobin back to hemoglobin, which is the form of the protein that is responsible for carrying oxygen in the blood. Methylene Blue has also been used off-label for other conditions, such as vasculitis and Alzheimer's disease, although its effectiveness for these uses is not well established.

It is important to note that Methylene Blue should be used with caution, as it can cause serious side effects in some people, particularly those with kidney or liver problems, or those who are taking certain medications. It is also important to follow the instructions of a healthcare provider when using this medication, as improper use can lead to toxicity.

The myocardium is the middle layer of the heart wall, composed of specialized cardiac muscle cells that are responsible for pumping blood throughout the body. It forms the thickest part of the heart wall and is divided into two sections: the left ventricle, which pumps oxygenated blood to the rest of the body, and the right ventricle, which pumps deoxygenated blood to the lungs.

The myocardium contains several types of cells, including cardiac muscle fibers, connective tissue, nerves, and blood vessels. The muscle fibers are arranged in a highly organized pattern that allows them to contract in a coordinated manner, generating the force necessary to pump blood through the heart and circulatory system.

Damage to the myocardium can occur due to various factors such as ischemia (reduced blood flow), infection, inflammation, or genetic disorders. This damage can lead to several cardiac conditions, including heart failure, arrhythmias, and cardiomyopathy.

Pyrophosphatases are enzymes that catalyze the hydrolysis or cleavage of pyrophosphate (PPi) into two inorganic phosphate (Pi) molecules. This reaction is essential for many biochemical processes, such as energy metabolism and biosynthesis pathways, where pyrophosphate is generated as a byproduct. By removing the pyrophosphate, pyrophosphatases help drive these reactions forward and maintain the thermodynamic equilibrium.

There are several types of pyrophosphatases found in various organisms and cellular compartments, including:

1. Inorganic Pyrophosphatase (PPiase): This enzyme is widely distributed across all kingdoms of life and is responsible for hydrolyzing inorganic pyrophosphate into two phosphates. It plays a crucial role in maintaining the cellular energy balance by ensuring that the reverse reaction, the formation of pyrophosphate from two phosphates, does not occur spontaneously.
2. Nucleotide Pyrophosphatases: These enzymes hydrolyze the pyrophosphate bond in nucleoside triphosphates (NTPs) and deoxynucleoside triphosphates (dNTPs), converting them into nucleoside monophosphates (NMPs) or deoxynucleoside monophosphates (dNMPs). This reaction is important for regulating the levels of NTPs and dNTPs in cells, which are necessary for DNA and RNA synthesis.
3. ATPases and GTPases: These enzymes belong to a larger family of P-loop NTPases that use the energy released from pyrophosphate bond hydrolysis to perform mechanical work or transport ions across membranes. Examples include the F1F0-ATP synthase, which synthesizes ATP using a proton gradient, and various molecular motors like myosin, kinesin, and dynein, which move along cytoskeletal filaments.

Overall, pyrophosphatases are essential for maintaining cellular homeostasis by regulating the levels of nucleotides and providing energy for various cellular processes.

I'm sorry for any confusion, but "Pyridines" is not a medical term. It is a chemical term that refers to a class of organic compounds with the chemical structure of a six-membered ring containing one nitrogen atom and five carbon atoms (heterocyclic aromatic compound).

In a biological or medical context, pyridine derivatives can be found in various natural and synthetic substances. For example, some medications contain pyridine rings as part of their chemical structure. However, "Pyridines" itself is not a medical term or condition.

Calmodulin is a small, ubiquitous calcium-binding protein that plays a critical role in various intracellular signaling pathways. It functions as a calcium sensor, binding to and regulating the activity of numerous target proteins upon calcium ion (Ca^2+^) binding. Calmodulin is expressed in all eukaryotic cells and participates in many cellular processes, including muscle contraction, neurotransmitter release, gene expression, metabolism, and cell cycle progression.

The protein contains four EF-hand motifs that can bind Ca^2+^ ions. Upon calcium binding, conformational changes occur in the calmodulin structure, exposing hydrophobic surfaces that facilitate its interaction with target proteins. Calmodulin's targets include enzymes (such as protein kinases and phosphatases), ion channels, transporters, and cytoskeletal components. By modulating the activity of these proteins, calmodulin helps regulate essential cellular functions in response to changes in intracellular Ca^2+^ concentrations.

Calmodulin's molecular weight is approximately 17 kDa, and it consists of a single polypeptide chain with 148-150 amino acid residues. The protein can be found in both the cytoplasm and the nucleus of cells. In addition to its role as a calcium sensor, calmodulin has been implicated in various pathological conditions, including cancer, neurodegenerative diseases, and cardiovascular disorders.

Adenine is a purine nucleotide base that is a fundamental component of DNA and RNA, the genetic material of living organisms. In DNA, adenine pairs with thymine via double hydrogen bonds, while in RNA, it pairs with uracil. Adenine is essential for the structure and function of nucleic acids, as well as for energy transfer reactions in cells through its role in the formation of adenosine triphosphate (ATP), the primary energy currency of the cell.

'Aplysia' is a genus of marine mollusks belonging to the family Aplysiidae, also known as sea hares. These are large, slow-moving herbivores that inhabit temperate and tropical coastal waters worldwide. They have a unique appearance with a soft, ear-like parapodia on either side of their body and a rhinophore at the front end, which they use to detect chemical cues in their environment.

One of the reasons 'Aplysia' is well-known in the medical and scientific community is because of its use as a model organism in neuroscience research. The simple nervous system of 'Aplysia' has made it an ideal subject for studying the basic principles of learning and memory at the cellular level.

In particular, the work of Nobel laureate Eric Kandel and his colleagues on 'Aplysia' helped to establish important concepts in synaptic plasticity, a key mechanism underlying learning and memory. By investigating how sensory stimulation can modify the strength of connections between neurons in 'Aplysia', researchers have gained valuable insights into the molecular and cellular mechanisms that underlie learning and memory processes in all animals, including humans.

The penis is a part of the male reproductive and urinary systems. It has three parts: the root, the body, and the glans. The root attaches to the pelvic bone and the body makes up the majority of the free-hanging portion. The glans is the cone-shaped end that protects the urethra, the tube inside the penis that carries urine from the bladder and semen from the testicles.

The penis has a dual function - it acts as a conduit for both urine and semen. During sexual arousal, the penis becomes erect when blood fills two chambers inside its shaft. This process is facilitated by the relaxation of the smooth muscles in the arterial walls and the trappping of blood in the corpora cavernosa. The stiffness of the penis enables sexual intercourse. After ejaculation, or when the sexual arousal passes, the muscles contract and the blood flows out of the penis back into the body, causing it to become flaccid again.

The foreskin, a layer of skin that covers the glans, is sometimes removed in a procedure called circumcision. Circumcision is often performed for religious or cultural reasons, or as a matter of family custom. In some countries, it's also done for medical reasons, such as to treat conditions like phimosis (an inability to retract the foreskin) or balanitis (inflammation of the glans).

It's important to note that any changes in appearance, size, or function of the penis should be evaluated by a healthcare professional, as they could indicate an underlying medical condition.

Membrane potential is the electrical potential difference across a cell membrane, typically for excitable cells such as nerve and muscle cells. It is the difference in electric charge between the inside and outside of a cell, created by the selective permeability of the cell membrane to different ions. The resting membrane potential of a typical animal cell is around -70 mV, with the interior being negative relative to the exterior. This potential is generated and maintained by the active transport of ions across the membrane, primarily through the action of the sodium-potassium pump. Membrane potentials play a crucial role in many physiological processes, including the transmission of nerve impulses and the contraction of muscle cells.

Muscle relaxation, in a medical context, refers to the process of reducing tension and promoting relaxation in the skeletal muscles. This can be achieved through various techniques, including progressive muscle relaxation (PMR), where individuals consciously tense and then release specific muscle groups in a systematic manner.

PMR has been shown to help reduce anxiety, stress, and muscle tightness, and improve overall well-being. It is often used as a complementary therapy in conjunction with other treatments for conditions such as chronic pain, headaches, and insomnia.

Additionally, muscle relaxation can also be facilitated through pharmacological interventions, such as the use of muscle relaxant medications. These drugs work by inhibiting the transmission of signals between nerves and muscles, leading to a reduction in muscle tone and spasticity. They are commonly used to treat conditions such as multiple sclerosis, cerebral palsy, and spinal cord injuries.

Carbachol is a cholinergic agonist, which means it stimulates the parasympathetic nervous system by mimicking the action of acetylcholine, a neurotransmitter that is involved in transmitting signals between nerves and muscles. Carbachol binds to both muscarinic and nicotinic receptors, but its effects are more pronounced on muscarinic receptors.

Carbachol is used in medical treatments to produce miosis (pupil constriction), lower intraocular pressure, and stimulate gastrointestinal motility. It can also be used as a diagnostic tool to test for certain conditions such as Hirschsprung's disease.

Like any medication, carbachol can have side effects, including sweating, salivation, nausea, vomiting, diarrhea, bradycardia (slow heart rate), and bronchoconstriction (narrowing of the airways in the lungs). It should be used with caution and under the supervision of a healthcare professional.

Glucagon is a hormone produced by the alpha cells of the pancreas. Its main function is to regulate glucose levels in the blood by stimulating the liver to convert stored glycogen into glucose, which can then be released into the bloodstream. This process helps to raise blood sugar levels when they are too low, such as during hypoglycemia.

Glucagon is a 29-amino acid polypeptide that is derived from the preproglucagon protein. It works by binding to glucagon receptors on liver cells, which triggers a series of intracellular signaling events that lead to the activation of enzymes involved in glycogen breakdown.

In addition to its role in glucose regulation, glucagon has also been shown to have other physiological effects, such as promoting lipolysis (the breakdown of fat) and inhibiting gastric acid secretion. Glucagon is often used clinically in the treatment of hypoglycemia, as well as in diagnostic tests to assess pancreatic function.

Aminoquinolines are a class of drugs that contain a quinoline chemical structure and an amino group. They are primarily used as antimalarial agents, with the most well-known members of this class being chloroquine and hydroxychloroquine. These drugs work by inhibiting the parasite's ability to digest hemoglobin in the red blood cells, which is necessary for its survival and reproduction.

In addition to their antimalarial properties, aminoquinolines have also been studied for their potential anti-inflammatory and immunomodulatory effects. They have been investigated as a treatment for various autoimmune diseases, such as rheumatoid arthritis and lupus, although their use in these conditions is not yet widely accepted.

It's important to note that aminoquinolines can have significant side effects, including gastrointestinal symptoms, retinopathy, and cardiac toxicity. They should only be used under the close supervision of a healthcare provider, and their use may be contraindicated in certain populations, such as pregnant women or individuals with preexisting heart conditions.

Hydrolysis is a chemical process, not a medical one. However, it is relevant to medicine and biology.

Hydrolysis is the breakdown of a chemical compound due to its reaction with water, often resulting in the formation of two or more simpler compounds. In the context of physiology and medicine, hydrolysis is a crucial process in various biological reactions, such as the digestion of food molecules like proteins, carbohydrates, and fats. Enzymes called hydrolases catalyze these hydrolysis reactions to speed up the breakdown process in the body.

Nitric oxide (NO) donors are pharmacological agents that release nitric oxide in the body when they are metabolized. Nitric oxide is a molecule that plays an important role as a signaling messenger in the cardiovascular, nervous, and immune systems. It helps regulate blood flow, relax smooth muscle, inhibit platelet aggregation, and modulate inflammatory responses.

NO donors can be used medically to treat various conditions, such as hypertension, angina, heart failure, and pulmonary hypertension, by promoting vasodilation and improving blood flow. Some examples of NO donors include nitroglycerin, isosorbide dinitrate, sodium nitroprusside, and molsidomine. These drugs work by releasing nitric oxide slowly over time, which then interacts with the enzyme soluble guanylate cyclase to produce cyclic guanosine monophosphate (cGMP), leading to relaxation of smooth muscle and vasodilation.

It is important to note that NO donors can have side effects, such as headache, dizziness, and hypotension, due to their vasodilatory effects. Therefore, they should be used under the guidance of a healthcare professional.

Pulmonary hypertension is a medical condition characterized by increased blood pressure in the pulmonary arteries, which are the blood vessels that carry blood from the right side of the heart to the lungs. This results in higher than normal pressures in the pulmonary circulation and can lead to various symptoms and complications.

Pulmonary hypertension is typically defined as a mean pulmonary artery pressure (mPAP) greater than or equal to 25 mmHg at rest, as measured by right heart catheterization. The World Health Organization (WHO) classifies pulmonary hypertension into five groups based on the underlying cause:

1. Pulmonary arterial hypertension (PAH): This group includes idiopathic PAH, heritable PAH, drug-induced PAH, and associated PAH due to conditions such as connective tissue diseases, HIV infection, portal hypertension, congenital heart disease, and schistosomiasis.
2. Pulmonary hypertension due to left heart disease: This group includes conditions that cause elevated left atrial pressure, such as left ventricular systolic or diastolic dysfunction, valvular heart disease, and congenital cardiovascular shunts.
3. Pulmonary hypertension due to lung diseases and/or hypoxia: This group includes chronic obstructive pulmonary disease (COPD), interstitial lung disease, sleep-disordered breathing, alveolar hypoventilation disorders, and high altitude exposure.
4. Chronic thromboembolic pulmonary hypertension (CTEPH): This group includes persistent obstruction of the pulmonary arteries due to organized thrombi or emboli.
5. Pulmonary hypertension with unclear and/or multifactorial mechanisms: This group includes hematologic disorders, systemic disorders, metabolic disorders, and other conditions that can cause pulmonary hypertension but do not fit into the previous groups.

Symptoms of pulmonary hypertension may include shortness of breath, fatigue, chest pain, lightheadedness, and syncope (fainting). Diagnosis typically involves a combination of medical history, physical examination, imaging studies, and invasive testing such as right heart catheterization. Treatment depends on the underlying cause but may include medications, oxygen therapy, pulmonary rehabilitation, and, in some cases, surgical intervention.

Calcimycin is a ionophore compound that is produced by the bacterium Streptomyces chartreusensis. It is also known as Calcineurin A inhibitor because it can bind to and inhibit the activity of calcineurin, a protein phosphatase. In medical research, calcimycin is often used to study calcium signaling in cells.
It has been also used in laboratory studies for its antiproliferative and pro-apoptotic effects on certain types of cancer cells. However, it is not approved for use as a drug in humans.

Purinergic P1 receptor antagonists are a class of pharmaceutical drugs that block the activity of purinergic P1 receptors, which are a type of G-protein coupled receptor found in many tissues throughout the body. These receptors are activated by extracellular nucleotides such as adenosine and ATP, and play important roles in regulating a variety of physiological processes, including cardiovascular function, neurotransmission, and immune response.

Purinergic P1 receptor antagonists work by binding to these receptors and preventing them from being activated by nucleotides. This can have various therapeutic effects, depending on the specific receptor subtype that is targeted. For example, A1 receptor antagonists have been shown to improve cardiac function in heart failure, while A2A receptor antagonists have potential as anti-inflammatory and neuroprotective agents.

However, it's important to note that the use of purinergic P1 receptor antagonists is still an area of active research, and more studies are needed to fully understand their mechanisms of action and therapeutic potential.

Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.

Adenosine A2A receptor is a type of G protein-coupled receptor that binds to the endogenous purine nucleoside, adenosine. It is a subtype of the A2 receptor along with the A2B receptor and is widely distributed throughout the body, particularly in the brain, heart, and immune system.

The A2A receptor plays an essential role in various physiological processes, including modulation of neurotransmission, cardiovascular function, and immune response. In the brain, activation of A2A receptors can have both excitatory and inhibitory effects on neuronal activity, depending on the location and context.

In the heart, A2A receptor activation has a negative chronotropic effect, reducing heart rate, and a negative inotropic effect, decreasing contractility. In the immune system, A2A receptors are involved in regulating inflammation and immune cell function.

Pharmacologically, A2A receptor agonists have been investigated for their potential therapeutic benefits in various conditions, including Parkinson's disease, chronic pain, ischemia-reperfusion injury, and cancer. Conversely, A2A receptor antagonists have also been studied as a potential treatment for neurodegenerative disorders, such as Alzheimer's disease, and addiction.

Dinoprostone is a prostaglandin E2 analog used in medical practice for the induction of labor and ripening of the cervix in pregnant women. It is available in various forms, including vaginal suppositories, gel, and tablets. Dinoprostone works by stimulating the contraction of uterine muscles and promoting cervical dilation, which helps in facilitating a successful delivery.

It's important to note that dinoprostone should only be administered under the supervision of a healthcare professional, as its use is associated with certain risks and side effects, including uterine hyperstimulation, fetal distress, and maternal infection. The dosage and duration of treatment are carefully monitored to minimize these risks and ensure the safety of both the mother and the baby.

Epoprostenol is a medication that belongs to a class of drugs called prostaglandins. It is a synthetic analog of a natural substance in the body called prostacyclin, which widens blood vessels and has anti-platelet effects. Epoprostenol is used to treat pulmonary arterial hypertension (PAH), a condition characterized by high blood pressure in the arteries that supply blood to the lungs.

Epoprostenol works by relaxing the smooth muscle in the walls of the pulmonary arteries, which reduces the resistance to blood flow and lowers the pressure within these vessels. This helps improve symptoms such as shortness of breath, fatigue, and chest pain, and can also prolong survival in people with PAH.

Epoprostenol is administered continuously through a small pump that delivers the medication directly into the bloodstream. It is a potent vasodilator, which means it can cause a sudden drop in blood pressure if not given carefully. Therefore, it is usually started in a hospital setting under close medical supervision.

Common side effects of epoprostenol include headache, flushing, jaw pain, nausea, vomiting, diarrhea, and muscle or joint pain. More serious side effects can include bleeding, infection at the site of the catheter, and an allergic reaction to the medication.

Phosphorylation is the process of adding a phosphate group (a molecule consisting of one phosphorus atom and four oxygen atoms) to a protein or other organic molecule, which is usually done by enzymes called kinases. This post-translational modification can change the function, localization, or activity of the target molecule, playing a crucial role in various cellular processes such as signal transduction, metabolism, and regulation of gene expression. Phosphorylation is reversible, and the removal of the phosphate group is facilitated by enzymes called phosphatases.

Epinephrine, also known as adrenaline, is a hormone and a neurotransmitter that is produced in the body. It is released by the adrenal glands in response to stress or excitement, and it prepares the body for the "fight or flight" response. Epinephrine works by binding to specific receptors in the body, which causes a variety of physiological effects, including increased heart rate and blood pressure, improved muscle strength and alertness, and narrowing of the blood vessels in the skin and intestines. It is also used as a medication to treat various medical conditions, such as anaphylaxis (a severe allergic reaction), cardiac arrest, and low blood pressure.

Norepinephrine, also known as noradrenaline, is a neurotransmitter and a hormone that is primarily produced in the adrenal glands and is released into the bloodstream in response to stress or physical activity. It plays a crucial role in the "fight-or-flight" response by preparing the body for action through increasing heart rate, blood pressure, respiratory rate, and glucose availability.

As a neurotransmitter, norepinephrine is involved in regulating various functions of the nervous system, including attention, perception, motivation, and arousal. It also plays a role in modulating pain perception and responding to stressful or emotional situations.

In medical settings, norepinephrine is used as a vasopressor medication to treat hypotension (low blood pressure) that can occur during septic shock, anesthesia, or other critical illnesses. It works by constricting blood vessels and increasing heart rate, which helps to improve blood pressure and perfusion of vital organs.

Histamine is defined as a biogenic amine that is widely distributed throughout the body and is involved in various physiological functions. It is derived primarily from the amino acid histidine by the action of histidine decarboxylase. Histamine is stored in granules (along with heparin and proteases) within mast cells and basophils, and is released upon stimulation or degranulation of these cells.

Once released into the tissues and circulation, histamine exerts a wide range of pharmacological actions through its interaction with four types of G protein-coupled receptors (H1, H2, H3, and H4 receptors). Histamine's effects are diverse and include modulation of immune responses, contraction and relaxation of smooth muscle, increased vascular permeability, stimulation of gastric acid secretion, and regulation of neurotransmission.

Histamine is also a potent mediator of allergic reactions and inflammation, causing symptoms such as itching, sneezing, runny nose, and wheezing. Antihistamines are commonly used to block the actions of histamine at H1 receptors, providing relief from these symptoms.

S-Nitroso-N-Acetylpenicillamine (SNAP) is not a medication itself, but rather a chemical compound that is used in laboratory research. It is a nitrosothiol, which means it contains a nitric oxide group (NO) attached to a sulfur atom in a thiol group (a type of organic compound containing a sulfhydryl group, -SH).

Nitric oxide is a small signaling molecule that plays an important role in various biological processes, including the regulation of blood flow, immune response, and neurotransmission. SNAP is often used as a nitric oxide donor in scientific studies to investigate the effects of nitric oxide on different cells and tissues.

SNAP can release nitric oxide under certain conditions, such as in the presence of reducing agents or at acidic pH levels. This makes it useful for studying the mechanisms of nitric oxide-mediated signaling pathways and its potential therapeutic applications. However, SNAP is not used as a medication in clinical practice due to its instability and potential toxicity.

Quinoxalines are not a medical term, but rather an organic chemical compound. They are a class of heterocyclic aromatic compounds made up of a benzene ring fused to a pyrazine ring. Quinoxalines have no specific medical relevance, but some of their derivatives have been synthesized and used in medicinal chemistry as antibacterial, antifungal, and antiviral agents. They are also used in the production of dyes and pigments.

I believe there may be some confusion in your question. "Rabbits" is a common name used to refer to the Lagomorpha species, particularly members of the family Leporidae. They are small mammals known for their long ears, strong legs, and quick reproduction.

However, if you're referring to "rabbits" in a medical context, there is a term called "rabbit syndrome," which is a rare movement disorder characterized by repetitive, involuntary movements of the fingers, resembling those of a rabbit chewing. It is also known as "finger-chewing chorea." This condition is usually associated with certain medications, particularly antipsychotics, and typically resolves when the medication is stopped or adjusted.

A cell line is a culture of cells that are grown in a laboratory for use in research. These cells are usually taken from a single cell or group of cells, and they are able to divide and grow continuously in the lab. Cell lines can come from many different sources, including animals, plants, and humans. They are often used in scientific research to study cellular processes, disease mechanisms, and to test new drugs or treatments. Some common types of human cell lines include HeLa cells (which come from a cancer patient named Henrietta Lacks), HEK293 cells (which come from embryonic kidney cells), and HUVEC cells (which come from umbilical vein endothelial cells). It is important to note that cell lines are not the same as primary cells, which are cells that are taken directly from a living organism and have not been grown in the lab.

Secretin is a hormone that is produced and released by the S cells in the duodenum, which is the first part of the small intestine. It is released in response to the presence of acidic chyme (partially digested food) entering the duodenum from the stomach. Secretin stimulates the pancreas to produce bicarbonate-rich alkaline secretions, which help neutralize the acidity of the chyme and create an optimal environment for enzymatic digestion in the small intestine.

Additionally, secretin also promotes the production of watery fluids from the liver, which aids in the digestion process. Overall, secretin plays a crucial role in maintaining the pH balance and facilitating proper nutrient absorption in the gastrointestinal tract.

Purinergic P1 receptors are a type of G-protein coupled receptor that bind to nucleotides such as adenosine. These receptors are involved in a variety of physiological processes, including modulation of neurotransmitter release, cardiovascular function, and immune response. There are four subtypes of P1 receptors (A1, A2A, A2B, and A3) that have different signaling pathways and functions. Activation of these receptors can lead to a variety of cellular responses, including inhibition or stimulation of adenylyl cyclase activity, changes in intracellular calcium levels, and activation of various protein kinases. They play important roles in the central nervous system, cardiovascular system, respiratory system, gastrointestinal system, and immune system.

Protein kinases are a group of enzymes that play a crucial role in many cellular processes by adding phosphate groups to other proteins, a process known as phosphorylation. This modification can activate or deactivate the target protein's function, thereby regulating various signaling pathways within the cell. Protein kinases are essential for numerous biological functions, including metabolism, signal transduction, cell cycle progression, and apoptosis (programmed cell death). Abnormal regulation of protein kinases has been implicated in several diseases, such as cancer, diabetes, and neurological disorders.

Muscle contraction is the physiological process in which muscle fibers shorten and generate force, leading to movement or stability of a body part. This process involves the sliding filament theory where thick and thin filaments within the sarcomeres (the functional units of muscles) slide past each other, facilitated by the interaction between myosin heads and actin filaments. The energy required for this action is provided by the hydrolysis of adenosine triphosphate (ATP). Muscle contractions can be voluntary or involuntary, and they play a crucial role in various bodily functions such as locomotion, circulation, respiration, and posture maintenance.

The trachea, also known as the windpipe, is a tube-like structure in the respiratory system that connects the larynx (voice box) to the bronchi (the two branches leading to each lung). It is composed of several incomplete rings of cartilage and smooth muscle, which provide support and flexibility. The trachea plays a crucial role in directing incoming air to the lungs during inspiration and outgoing air to the larynx during expiration.

Myocardial contraction refers to the rhythmic and forceful shortening of heart muscle cells (myocytes) in the myocardium, which is the muscular wall of the heart. This process is initiated by electrical signals generated by the sinoatrial node, causing a wave of depolarization that spreads throughout the heart.

During myocardial contraction, calcium ions flow into the myocytes, triggering the interaction between actin and myosin filaments, which are the contractile proteins in the muscle cells. This interaction causes the myofilaments to slide past each other, resulting in the shortening of the sarcomeres (the functional units of muscle contraction) and ultimately leading to the contraction of the heart muscle.

Myocardial contraction is essential for pumping blood throughout the body and maintaining adequate circulation to vital organs. Any impairment in myocardial contractility can lead to various cardiac disorders, such as heart failure, cardiomyopathy, and arrhythmias.

In the context of medical terminology, "light" doesn't have a specific or standardized definition on its own. However, it can be used in various medical terms and phrases. For example, it could refer to:

1. Visible light: The range of electromagnetic radiation that can be detected by the human eye, typically between wavelengths of 400-700 nanometers. This is relevant in fields such as ophthalmology and optometry.
2. Therapeutic use of light: In some therapies, light is used to treat certain conditions. An example is phototherapy, which uses various wavelengths of ultraviolet (UV) or visible light for conditions like newborn jaundice, skin disorders, or seasonal affective disorder.
3. Light anesthesia: A state of reduced consciousness in which the patient remains responsive to verbal commands and physical stimulation. This is different from general anesthesia where the patient is completely unconscious.
4. Pain relief using light: Certain devices like transcutaneous electrical nerve stimulation (TENS) units have a 'light' setting, indicating lower intensity or frequency of electrical impulses used for pain management.

Without more context, it's hard to provide a precise medical definition of 'light'.

Adenine nucleotides are molecules that consist of a nitrogenous base called adenine, which is linked to a sugar molecule (ribose in the case of adenosine monophosphate or AMP, and deoxyribose in the case of adenosine diphosphate or ADP and adenosine triphosphate or ATP) and one, two, or three phosphate groups. These molecules play a crucial role in energy transfer and metabolism within cells.

AMP contains one phosphate group, while ADP contains two phosphate groups, and ATP contains three phosphate groups. When a phosphate group is removed from ATP, energy is released, which can be used to power various cellular processes such as muscle contraction, nerve impulse transmission, and protein synthesis. The reverse reaction, in which a phosphate group is added back to ADP or AMP to form ATP, requires energy input and often involves the breakdown of nutrients such as glucose or fatty acids.

In addition to their role in energy metabolism, adenine nucleotides also serve as precursors for other important molecules, including DNA and RNA, coenzymes, and signaling molecules.

Penicillamine is a medication that belongs to a class of drugs called chelating agents. It works by binding to heavy metals in the body, such as lead, mercury, or copper, and forming a compound that can be excreted in the urine. This helps to remove these harmful substances from the body.

Penicillamine is also used to treat certain medical conditions, such as rheumatoid arthritis, Wilson's disease (a genetic disorder that causes copper accumulation in the body), and cystinuria (a genetic disorder that causes an amino acid called cystine to accumulate in the kidneys and form stones).

It is important to note that penicillamine can have serious side effects, including kidney damage, so it should be used under the close supervision of a healthcare provider.

Vasoactive Intestinal Peptide (VIP) is a 28-amino acid polypeptide hormone that has potent vasodilatory, secretory, and neurotransmitter effects. It is widely distributed throughout the body, including in the gastrointestinal tract, where it is synthesized and released by nerve cells (neurons) in the intestinal mucosa. VIP plays a crucial role in regulating various physiological functions such as intestinal secretion, motility, and blood flow. It also has immunomodulatory effects and may play a role in neuroprotection. High levels of VIP are found in the brain, where it acts as a neurotransmitter or neuromodulator and is involved in various cognitive functions such as learning, memory, and social behavior.

A smooth muscle within the vascular system refers to the involuntary, innervated muscle that is found in the walls of blood vessels. These muscles are responsible for controlling the diameter of the blood vessels, which in turn regulates blood flow and blood pressure. They are called "smooth" muscles because their individual muscle cells do not have the striations, or cross-striped patterns, that are observed in skeletal and cardiac muscle cells. Smooth muscle in the vascular system is controlled by the autonomic nervous system and by hormones, and can contract or relax slowly over a period of time.

Messenger RNA (mRNA) is a type of RNA (ribonucleic acid) that carries genetic information copied from DNA in the form of a series of three-base code "words," each of which specifies a particular amino acid. This information is used by the cell's machinery to construct proteins, a process known as translation. After being transcribed from DNA, mRNA travels out of the nucleus to the ribosomes in the cytoplasm where protein synthesis occurs. Once the protein has been synthesized, the mRNA may be degraded and recycled. Post-transcriptional modifications can also occur to mRNA, such as alternative splicing and addition of a 5' cap and a poly(A) tail, which can affect its stability, localization, and translation efficiency.

Retinal rod photoreceptor cells are specialized neurons in the retina of the eye that are primarily responsible for vision in low light conditions. They contain a light-sensitive pigment called rhodopsin, which undergoes a chemical change when struck by a single photon of light. This triggers a cascade of biochemical reactions that ultimately leads to the generation of electrical signals, which are then transmitted to the brain via the optic nerve.

Rod cells do not provide color vision or fine detail, but they allow us to detect motion and see in dim light. They are more sensitive to light than cone cells, which are responsible for color vision and detailed sight in bright light conditions. Rod cells are concentrated at the outer edges of the retina, forming a crescent-shaped region called the peripheral retina, with fewer rod cells located in the central region of the retina known as the fovea.

Electric stimulation, also known as electrical nerve stimulation or neuromuscular electrical stimulation, is a therapeutic treatment that uses low-voltage electrical currents to stimulate nerves and muscles. It is often used to help manage pain, promote healing, and improve muscle strength and mobility. The electrical impulses can be delivered through electrodes placed on the skin or directly implanted into the body.

In a medical context, electric stimulation may be used for various purposes such as:

1. Pain management: Electric stimulation can help to block pain signals from reaching the brain and promote the release of endorphins, which are natural painkillers produced by the body.
2. Muscle rehabilitation: Electric stimulation can help to strengthen muscles that have become weak due to injury, illness, or surgery. It can also help to prevent muscle atrophy and improve range of motion.
3. Wound healing: Electric stimulation can promote tissue growth and help to speed up the healing process in wounds, ulcers, and other types of injuries.
4. Urinary incontinence: Electric stimulation can be used to strengthen the muscles that control urination and reduce symptoms of urinary incontinence.
5. Migraine prevention: Electric stimulation can be used as a preventive treatment for migraines by applying electrical impulses to specific nerves in the head and neck.

It is important to note that electric stimulation should only be administered under the guidance of a qualified healthcare professional, as improper use can cause harm or discomfort.

Potassium is a essential mineral and an important electrolyte that is widely distributed in the human body. The majority of potassium in the body (approximately 98%) is found within cells, with the remaining 2% present in blood serum and other bodily fluids. Potassium plays a crucial role in various physiological processes, including:

1. Regulation of fluid balance and maintenance of normal blood pressure through its effects on vascular tone and sodium excretion.
2. Facilitation of nerve impulse transmission and muscle contraction by participating in the generation and propagation of action potentials.
3. Protein synthesis, enzyme activation, and glycogen metabolism.
4. Regulation of acid-base balance through its role in buffering systems.

The normal serum potassium concentration ranges from 3.5 to 5.0 mEq/L (milliequivalents per liter) or mmol/L (millimoles per liter). Potassium levels outside this range can have significant clinical consequences, with both hypokalemia (low potassium levels) and hyperkalemia (high potassium levels) potentially leading to serious complications such as cardiac arrhythmias, muscle weakness, and respiratory failure.

Potassium is primarily obtained through the diet, with rich sources including fruits (e.g., bananas, oranges, and apricots), vegetables (e.g., leafy greens, potatoes, and tomatoes), legumes, nuts, dairy products, and meat. In cases of deficiency or increased needs, potassium supplements may be recommended under the guidance of a healthcare professional.

Sulfonamides are a group of synthetic antibacterial drugs that contain the sulfonamide group (SO2NH2) in their chemical structure. They are bacteriostatic agents, meaning they inhibit bacterial growth rather than killing them outright. Sulfonamides work by preventing the bacteria from synthesizing folic acid, which is essential for their survival.

The first sulfonamide drug was introduced in the 1930s and since then, many different sulfonamides have been developed with varying chemical structures and pharmacological properties. They are used to treat a wide range of bacterial infections, including urinary tract infections, respiratory tract infections, skin and soft tissue infections, and ear infections.

Some common sulfonamide drugs include sulfisoxazole, sulfamethoxazole, and trimethoprim-sulfamethoxazole (a combination of a sulfonamide and another antibiotic called trimethoprim). While sulfonamides are generally safe and effective when used as directed, they can cause side effects such as rash, nausea, and allergic reactions. It is important to follow the prescribing physician's instructions carefully and to report any unusual symptoms or side effects promptly.

Serotonin, also known as 5-hydroxytryptamine (5-HT), is a monoamine neurotransmitter that is found primarily in the gastrointestinal (GI) tract, blood platelets, and the central nervous system (CNS) of humans and other animals. It is produced by the conversion of the amino acid tryptophan to 5-hydroxytryptophan (5-HTP), and then to serotonin.

In the CNS, serotonin plays a role in regulating mood, appetite, sleep, memory, learning, and behavior, among other functions. It also acts as a vasoconstrictor, helping to regulate blood flow and blood pressure. In the GI tract, it is involved in peristalsis, the contraction and relaxation of muscles that moves food through the digestive system.

Serotonin is synthesized and stored in serotonergic neurons, which are nerve cells that use serotonin as their primary neurotransmitter. These neurons are found throughout the brain and spinal cord, and they communicate with other neurons by releasing serotonin into the synapse, the small gap between two neurons.

Abnormal levels of serotonin have been linked to a variety of disorders, including depression, anxiety, schizophrenia, and migraines. Medications that affect serotonin levels, such as selective serotonin reuptake inhibitors (SSRIs), are commonly used to treat these conditions.

I believe there might be a misunderstanding in your question. "Dogs" is not a medical term or condition. It is the common name for a domesticated carnivore of the family Canidae, specifically the genus Canis, which includes wolves, foxes, and other extant and extinct species of mammals. Dogs are often kept as pets and companions, and they have been bred in a wide variety of forms and sizes for different purposes, such as hunting, herding, guarding, assisting police and military forces, and providing companionship and emotional support.

If you meant to ask about a specific medical condition or term related to dogs, please provide more context so I can give you an accurate answer.

Glycerylphosphorylcholine (GPC) is not typically considered a medical term, but it is a choline-containing phospholipid that can be found in various tissues and fluids within the human body. It is also available as a dietary supplement. Here's a definition of Glycerylphosphorylcholine:

Glycerylphosphorylcholine (GPC) is a natural choline-containing compound that is present in various tissues and fluids within the human body, including neural tissue, muscle, and blood. It plays an essential role in the synthesis of the neurotransmitter acetylcholine, which is involved in memory, learning, and other cognitive functions. GPC can also be found in some foods, such as egg yolks and soybeans, and is available as a dietary supplement. In the body, GPC can be converted to phosphatidylcholine, another important phospholipid that is necessary for maintaining cell membrane structure and function.

The pulmonary artery is a large blood vessel that carries deoxygenated blood from the right ventricle of the heart to the lungs for oxygenation. It divides into two main branches, the right and left pulmonary arteries, which further divide into smaller vessels called arterioles, and then into a vast network of capillaries in the lungs where gas exchange occurs. The thin walls of these capillaries allow oxygen to diffuse into the blood and carbon dioxide to diffuse out, making the blood oxygen-rich before it is pumped back to the left side of the heart through the pulmonary veins. This process is crucial for maintaining proper oxygenation of the body's tissues and organs.

A cell membrane, also known as the plasma membrane, is a thin semi-permeable phospholipid bilayer that surrounds all cells in animals, plants, and microorganisms. It functions as a barrier to control the movement of substances in and out of the cell, allowing necessary molecules such as nutrients, oxygen, and signaling molecules to enter while keeping out harmful substances and waste products. The cell membrane is composed mainly of phospholipids, which have hydrophilic (water-loving) heads and hydrophobic (water-fearing) tails. This unique structure allows the membrane to be flexible and fluid, yet selectively permeable. Additionally, various proteins are embedded in the membrane that serve as channels, pumps, receptors, and enzymes, contributing to the cell's overall functionality and communication with its environment.

Spermatozoa are the male reproductive cells, or gametes, that are produced in the testes. They are microscopic, flagellated (tail-equipped) cells that are highly specialized for fertilization. A spermatozoon consists of a head, neck, and tail. The head contains the genetic material within the nucleus, covered by a cap-like structure called the acrosome which contains enzymes to help the sperm penetrate the female's egg (ovum). The long, thin tail propels the sperm forward through fluid, such as semen, enabling its journey towards the egg for fertilization.

Platelet aggregation is the clumping together of platelets (thrombocytes) in the blood, which is an essential step in the process of hemostasis (the stopping of bleeding) after injury to a blood vessel. When the inner lining of a blood vessel is damaged, exposure of subendothelial collagen and tissue factor triggers platelet activation. Activated platelets change shape, become sticky, and release the contents of their granules, which include ADP (adenosine diphosphate).

ADP then acts as a chemical mediator to attract and bind additional platelets to the site of injury, leading to platelet aggregation. This forms a plug that seals the damaged vessel and prevents further blood loss. Platelet aggregation is also a crucial component in the formation of blood clots (thrombosis) within blood vessels, which can have pathological consequences such as heart attacks and strokes if they obstruct blood flow to vital organs.

Insulin is a hormone produced by the beta cells of the pancreatic islets, primarily in response to elevated levels of glucose in the circulating blood. It plays a crucial role in regulating blood glucose levels and facilitating the uptake and utilization of glucose by peripheral tissues, such as muscle and adipose tissue, for energy production and storage. Insulin also inhibits glucose production in the liver and promotes the storage of excess glucose as glycogen or triglycerides.

Deficiency in insulin secretion or action leads to impaired glucose regulation and can result in conditions such as diabetes mellitus, characterized by chronic hyperglycemia and associated complications. Exogenous insulin is used as a replacement therapy in individuals with diabetes to help manage their blood glucose levels and prevent long-term complications.

Vasodilation is the widening or increase in diameter of blood vessels, particularly the involuntary relaxation of the smooth muscle in the tunica media (middle layer) of the arteriole walls. This results in an increase in blood flow and a decrease in vascular resistance. Vasodilation can occur due to various physiological and pathophysiological stimuli, such as local metabolic demands, neural signals, or pharmacological agents. It plays a crucial role in regulating blood pressure, tissue perfusion, and thermoregulation.

Catecholamines are a group of hormones and neurotransmitters that are derived from the amino acid tyrosine. The most well-known catecholamines are dopamine, norepinephrine (also known as noradrenaline), and epinephrine (also known as adrenaline). These hormones are produced by the adrenal glands and are released into the bloodstream in response to stress. They play important roles in the "fight or flight" response, increasing heart rate, blood pressure, and alertness. In addition to their role as hormones, catecholamines also function as neurotransmitters, transmitting signals in the nervous system. Disorders of catecholamine regulation can lead to a variety of medical conditions, including hypertension, mood disorders, and neurological disorders.

I'm sorry for any confusion, but "pyrazines" is not a term commonly used in medical definitions. Pyrazines are actually a class of organic compounds that contain a ring made up of two nitrogen atoms and three carbon atoms. They are found in various foods and contribute to their flavors. If you have any questions about organic chemistry or food science, I'd be happy to try to help!

"Rana catesbeiana" is the scientific name for the American bullfrog, which is not a medical term or concept. It belongs to the animal kingdom, specifically in the order Anura and family Ranidae. The American bullfrog is native to North America and is known for its large size and distinctive loud call.

However, if you are looking for a medical definition, I apologize for any confusion. Please provide more context or specify the term you would like me to define.

The brain is the central organ of the nervous system, responsible for receiving and processing sensory information, regulating vital functions, and controlling behavior, movement, and cognition. It is divided into several distinct regions, each with specific functions:

1. Cerebrum: The largest part of the brain, responsible for higher cognitive functions such as thinking, learning, memory, language, and perception. It is divided into two hemispheres, each controlling the opposite side of the body.
2. Cerebellum: Located at the back of the brain, it is responsible for coordinating muscle movements, maintaining balance, and fine-tuning motor skills.
3. Brainstem: Connects the cerebrum and cerebellum to the spinal cord, controlling vital functions such as breathing, heart rate, and blood pressure. It also serves as a relay center for sensory information and motor commands between the brain and the rest of the body.
4. Diencephalon: A region that includes the thalamus (a major sensory relay station) and hypothalamus (regulates hormones, temperature, hunger, thirst, and sleep).
5. Limbic system: A group of structures involved in emotional processing, memory formation, and motivation, including the hippocampus, amygdala, and cingulate gyrus.

The brain is composed of billions of interconnected neurons that communicate through electrical and chemical signals. It is protected by the skull and surrounded by three layers of membranes called meninges, as well as cerebrospinal fluid that provides cushioning and nutrients.

Sperm motility is the ability of sperm to move actively and effectively through the female reproductive tract towards the egg for fertilization. It is typically measured as the percentage of moving sperm in a sample, and their progressiveness or velocity. Normal human sperm motility is generally defined as forward progression of at least 25 micrometers per second, with at least 50% of sperm showing progressive motility. Reduced sperm motility, also known as asthenozoospermia, can negatively impact fertility and reproductive outcomes.

Nitric Oxide Synthase (NOS) is a group of enzymes that catalyze the production of nitric oxide (NO) from L-arginine. There are three distinct isoforms of NOS, each with different expression patterns and functions:

1. Neuronal Nitric Oxide Synthase (nNOS or NOS1): This isoform is primarily expressed in the nervous system and plays a role in neurotransmission, synaptic plasticity, and learning and memory processes.
2. Inducible Nitric Oxide Synthase (iNOS or NOS2): This isoform is induced by various stimuli such as cytokines, lipopolysaccharides, and hypoxia in a variety of cells including immune cells, endothelial cells, and smooth muscle cells. iNOS produces large amounts of NO, which functions as a potent effector molecule in the immune response, particularly in the defense against microbial pathogens.
3. Endothelial Nitric Oxide Synthase (eNOS or NOS3): This isoform is constitutively expressed in endothelial cells and produces low levels of NO that play a crucial role in maintaining vascular homeostasis by regulating vasodilation, inhibiting platelet aggregation, and preventing smooth muscle cell proliferation.

Overall, NOS plays an essential role in various physiological processes, including neurotransmission, immune response, cardiovascular function, and respiratory regulation. Dysregulation of NOS activity has been implicated in several pathological conditions such as hypertension, atherosclerosis, neurodegenerative diseases, and inflammatory disorders.

Blood platelets, also known as thrombocytes, are small, colorless cell fragments in our blood that play an essential role in normal blood clotting. They are formed in the bone marrow from large cells called megakaryocytes and circulate in the blood in an inactive state until they are needed to help stop bleeding. When a blood vessel is damaged, platelets become activated and change shape, releasing chemicals that attract more platelets to the site of injury. These activated platelets then stick together to form a plug, or clot, that seals the wound and prevents further blood loss. In addition to their role in clotting, platelets also help to promote healing by releasing growth factors that stimulate the growth of new tissue.

Adrenergic beta-antagonists, also known as beta blockers, are a class of medications that block the effects of adrenaline and noradrenaline (also known as epinephrine and norepinephrine) on beta-adrenergic receptors. These receptors are found in various tissues throughout the body, including the heart, lungs, and blood vessels.

Beta blockers work by binding to these receptors and preventing the activation of certain signaling pathways that lead to increased heart rate, force of heart contractions, and relaxation of blood vessels. As a result, beta blockers can lower blood pressure, reduce heart rate, and decrease the workload on the heart.

Beta blockers are used to treat a variety of medical conditions, including hypertension (high blood pressure), angina (chest pain), heart failure, irregular heart rhythms, migraines, and certain anxiety disorders. Some common examples of beta blockers include metoprolol, atenolol, propranolol, and bisoprolol.

It is important to note that while beta blockers can have many benefits, they can also cause side effects such as fatigue, dizziness, and shortness of breath. Additionally, sudden discontinuation of beta blocker therapy can lead to rebound hypertension or worsening chest pain. Therefore, it is important to follow the dosing instructions provided by a healthcare provider carefully when taking these medications.

Adenosine Triphosphate (ATP) is a high-energy molecule that stores and transports energy within cells. It is the main source of energy for most cellular processes, including muscle contraction, nerve impulse transmission, and protein synthesis. ATP is composed of a base (adenine), a sugar (ribose), and three phosphate groups. The bonds between these phosphate groups contain a significant amount of energy, which can be released when the bond between the second and third phosphate group is broken, resulting in the formation of adenosine diphosphate (ADP) and inorganic phosphate. This process is known as hydrolysis and can be catalyzed by various enzymes to drive a wide range of cellular functions. ATP can also be regenerated from ADP through various metabolic pathways, such as oxidative phosphorylation or substrate-level phosphorylation, allowing for the continuous supply of energy to cells.

Protein Kinase C (PKC) is a family of serine-threonine kinases that play crucial roles in various cellular signaling pathways. These enzymes are activated by second messengers such as diacylglycerol (DAG) and calcium ions (Ca2+), which result from the activation of cell surface receptors like G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs).

Once activated, PKC proteins phosphorylate downstream target proteins, thereby modulating their activities. This regulation is involved in numerous cellular processes, including cell growth, differentiation, apoptosis, and membrane trafficking. There are at least 10 isoforms of PKC, classified into three subfamilies based on their second messenger requirements and structural features: conventional (cPKC; α, βI, βII, and γ), novel (nPKC; δ, ε, η, and θ), and atypical (aPKC; ζ and ι/λ). Dysregulation of PKC signaling has been implicated in several diseases, such as cancer, diabetes, and neurological disorders.

Carbolines are a type of chemical compound that contain a carbazole or dibenzopyrrole structure. These compounds have a variety of uses, including as pharmaceuticals and dyes. Some carbolines have been studied for their potential medicinal properties, such as their ability to act as antioxidants or to inhibit the growth of certain types of cells. However, it is important to note that many carbolines are also known to be toxic and can cause harm if ingested or otherwise introduced into the body. As with any chemical compound, it is essential to use caution when handling carbolines and to follow all safety guidelines to minimize the risk of exposure.

An amino acid sequence is the specific order of amino acids in a protein or peptide molecule, formed by the linking of the amino group (-NH2) of one amino acid to the carboxyl group (-COOH) of another amino acid through a peptide bond. The sequence is determined by the genetic code and is unique to each type of protein or peptide. It plays a crucial role in determining the three-dimensional structure and function of proteins.

Animal disease models are specialized animals, typically rodents such as mice or rats, that have been genetically engineered or exposed to certain conditions to develop symptoms and physiological changes similar to those seen in human diseases. These models are used in medical research to study the pathophysiology of diseases, identify potential therapeutic targets, test drug efficacy and safety, and understand disease mechanisms.

The genetic modifications can include knockout or knock-in mutations, transgenic expression of specific genes, or RNA interference techniques. The animals may also be exposed to environmental factors such as chemicals, radiation, or infectious agents to induce the disease state.

Examples of animal disease models include:

1. Mouse models of cancer: Genetically engineered mice that develop various types of tumors, allowing researchers to study cancer initiation, progression, and metastasis.
2. Alzheimer's disease models: Transgenic mice expressing mutant human genes associated with Alzheimer's disease, which exhibit amyloid plaque formation and cognitive decline.
3. Diabetes models: Obese and diabetic mouse strains like the NOD (non-obese diabetic) or db/db mice, used to study the development of type 1 and type 2 diabetes, respectively.
4. Cardiovascular disease models: Atherosclerosis-prone mice, such as ApoE-deficient or LDLR-deficient mice, that develop plaque buildup in their arteries when fed a high-fat diet.
5. Inflammatory bowel disease models: Mice with genetic mutations affecting intestinal barrier function and immune response, such as IL-10 knockout or SAMP1/YitFc mice, which develop colitis.

Animal disease models are essential tools in preclinical research, but it is important to recognize their limitations. Differences between species can affect the translatability of results from animal studies to human patients. Therefore, researchers must carefully consider the choice of model and interpret findings cautiously when applying them to human diseases.

I apologize, but I am not able to provide a medical definition for "Egtazic Acid" because it is not a term that is recognized in the field of medicine or pharmacology. It is possible that you may have meant "Egтарic Acid," which also does not have a specific medical meaning, or "Ethylene Glycol Tetraacetic Acid (EGTA)," which is a chemical compound used in research and medicine for its ability to bind calcium ions. If you have any other questions, I would be happy to try to help answer them.

A drug interaction is the effect of combining two or more drugs, or a drug and another substance (such as food or alcohol), which can alter the effectiveness or side effects of one or both of the substances. These interactions can be categorized as follows:

1. Pharmacodynamic interactions: These occur when two or more drugs act on the same target organ or receptor, leading to an additive, synergistic, or antagonistic effect. For example, taking a sedative and an antihistamine together can result in increased drowsiness due to their combined depressant effects on the central nervous system.
2. Pharmacokinetic interactions: These occur when one drug affects the absorption, distribution, metabolism, or excretion of another drug. For example, taking certain antibiotics with grapefruit juice can increase the concentration of the antibiotic in the bloodstream, leading to potential toxicity.
3. Food-drug interactions: Some drugs may interact with specific foods, affecting their absorption, metabolism, or excretion. An example is the interaction between warfarin (a blood thinner) and green leafy vegetables, which can increase the risk of bleeding due to enhanced vitamin K absorption from the vegetables.
4. Drug-herb interactions: Some herbal supplements may interact with medications, leading to altered drug levels or increased side effects. For instance, St. John's Wort can decrease the effectiveness of certain antidepressants and oral contraceptives by inducing their metabolism.
5. Drug-alcohol interactions: Alcohol can interact with various medications, causing additive sedative effects, impaired judgment, or increased risk of liver damage. For example, combining alcohol with benzodiazepines or opioids can lead to dangerous levels of sedation and respiratory depression.

It is essential for healthcare providers and patients to be aware of potential drug interactions to minimize adverse effects and optimize treatment outcomes.

Inositol phosphates are a family of molecules that consist of an inositol ring, which is a six-carbon heterocyclic compound, linked to one or more phosphate groups. These molecules play important roles as intracellular signaling intermediates and are involved in various cellular processes such as cell growth, differentiation, and metabolism.

Inositol hexakisphosphate (IP6), also known as phytic acid, is a form of inositol phosphate that is found in plant-based foods. IP6 has the ability to bind to minerals such as calcium, magnesium, and iron, which can reduce their bioavailability in the body.

Inositol phosphates have been implicated in several diseases, including cancer, diabetes, and neurodegenerative disorders. For example, altered levels of certain inositol phosphates have been observed in cancer cells, suggesting that they may play a role in tumor growth and progression. Additionally, mutations in enzymes involved in the metabolism of inositol phosphates have been associated with several genetic diseases.

Hemodynamics is the study of how blood flows through the cardiovascular system, including the heart and the vascular network. It examines various factors that affect blood flow, such as blood volume, viscosity, vessel length and diameter, and pressure differences between different parts of the circulatory system. Hemodynamics also considers the impact of various physiological and pathological conditions on these variables, and how they in turn influence the function of vital organs and systems in the body. It is a critical area of study in fields such as cardiology, anesthesiology, and critical care medicine.

Cyclopropanes are a class of organic compounds that contain a cyclic structure consisting of three carbon atoms joined by single bonds, forming a three-membered ring. The strain in the cyclopropane ring is due to the fact that the ideal tetrahedral angle at each carbon atom (109.5 degrees) cannot be achieved in a three-membered ring, leading to significant angular strain.

Cyclopropanes are important in organic chemistry because of their unique reactivity and synthetic utility. They can undergo various reactions, such as ring-opening reactions, that allow for the formation of new carbon-carbon bonds and the synthesis of complex molecules. Cyclopropanes have also been used as anesthetics, although their use in this application has declined due to safety concerns.

Tumor Necrosis Factor-alpha (TNF-α) is a cytokine, a type of small signaling protein involved in immune response and inflammation. It is primarily produced by activated macrophages, although other cell types such as T-cells, natural killer cells, and mast cells can also produce it.

TNF-α plays a crucial role in the body's defense against infection and tissue injury by mediating inflammatory responses, activating immune cells, and inducing apoptosis (programmed cell death) in certain types of cells. It does this by binding to its receptors, TNFR1 and TNFR2, which are found on the surface of many cell types.

In addition to its role in the immune response, TNF-α has been implicated in the pathogenesis of several diseases, including autoimmune disorders such as rheumatoid arthritis, inflammatory bowel disease, and psoriasis, as well as cancer, where it can promote tumor growth and metastasis.

Therapeutic agents that target TNF-α, such as infliximab, adalimumab, and etanercept, have been developed to treat these conditions. However, these drugs can also increase the risk of infections and other side effects, so their use must be carefully monitored.

Nucleotidases are a class of enzymes that catalyze the hydrolysis of nucleotides into nucleosides and phosphate groups. Nucleotidases play important roles in various biological processes, including the regulation of nucleotide concentrations within cells, the salvage pathways for nucleotide synthesis, and the breakdown of nucleic acids during programmed cell death (apoptosis).

There are several types of nucleotidases that differ in their substrate specificity and subcellular localization. These include:

1. Nucleoside monophosphatases (NMPs): These enzymes hydrolyze nucleoside monophosphates (NMPs) into nucleosides and inorganic phosphate.
2. Nucleoside diphosphatases (NDPs): These enzymes hydrolyze nucleoside diphosphates (NDPs) into nucleoside monophosphates (NMPs) and inorganic phosphate.
3. Nucleoside triphosphatases (NTPs): These enzymes hydrolyze nucleoside triphosphates (NTPs) into nucleoside diphosphates (NDPs) and inorganic phosphate.
4. 5'-Nucleotidase: This enzyme specifically hydrolyzes the phosphate group from the 5' position of nucleoside monophosphates, producing nucleosides.
5. Pyrophosphatases: These enzymes hydrolyze pyrophosphates into two phosphate groups and play a role in regulating nucleotide metabolism.

Nucleotidases are widely distributed in nature and can be found in various tissues, organs, and biological fluids, including blood, urine, and cerebrospinal fluid. Dysregulation of nucleotidase activity has been implicated in several diseases, such as cancer, neurodegenerative disorders, and infectious diseases.

Acetylcholine is a neurotransmitter, a type of chemical messenger that transmits signals across a chemical synapse from one neuron (nerve cell) to another "target" neuron, muscle cell, or gland cell. It is involved in both peripheral and central nervous system functions.

In the peripheral nervous system, acetylcholine acts as a neurotransmitter at the neuromuscular junction, where it transmits signals from motor neurons to activate muscles. Acetylcholine also acts as a neurotransmitter in the autonomic nervous system, where it is involved in both the sympathetic and parasympathetic systems.

In the central nervous system, acetylcholine plays a role in learning, memory, attention, and arousal. Disruptions in cholinergic neurotransmission have been implicated in several neurological disorders, including Alzheimer's disease, Parkinson's disease, and myasthenia gravis.

Acetylcholine is synthesized from choline and acetyl-CoA by the enzyme choline acetyltransferase and is stored in vesicles at the presynaptic terminal of the neuron. When a nerve impulse arrives, the vesicles fuse with the presynaptic membrane, releasing acetylcholine into the synapse. The acetylcholine then binds to receptors on the postsynaptic membrane, triggering a response in the target cell. Acetylcholine is subsequently degraded by the enzyme acetylcholinesterase, which terminates its action and allows for signal transduction to be repeated.

Diterpenes are a class of naturally occurring compounds that are composed of four isoprene units, which is a type of hydrocarbon. They are synthesized by a wide variety of plants and animals, and are found in many different types of organisms, including fungi, insects, and marine organisms.

Diterpenes have a variety of biological activities and are used in medicine for their therapeutic effects. Some diterpenes have anti-inflammatory, antimicrobial, and antiviral properties, and are used to treat a range of conditions, including respiratory infections, skin disorders, and cancer.

Diterpenes can be further classified into different subgroups based on their chemical structure and biological activity. Some examples of diterpenes include the phytocannabinoids found in cannabis plants, such as THC and CBD, and the paclitaxel, a diterpene found in the bark of the Pacific yew tree that is used to treat cancer.

It's important to note that while some diterpenes have therapeutic potential, others may be toxic or have adverse effects, so it is essential to use them under the guidance and supervision of a healthcare professional.

Hydrogen-ion concentration, also known as pH, is a measure of the acidity or basicity of a solution. It is defined as the negative logarithm (to the base 10) of the hydrogen ion activity in a solution. The standard unit of measurement is the pH unit. A pH of 7 is neutral, less than 7 is acidic, and greater than 7 is basic.

In medical terms, hydrogen-ion concentration is important for maintaining homeostasis within the body. For example, in the stomach, a high hydrogen-ion concentration (low pH) is necessary for the digestion of food. However, in other parts of the body such as blood, a high hydrogen-ion concentration can be harmful and lead to acidosis. Conversely, a low hydrogen-ion concentration (high pH) in the blood can lead to alkalosis. Both acidosis and alkalosis can have serious consequences on various organ systems if not corrected.

I'm not able to find a medical definition for "Cyclic IMP" in standard medical resources. It is possible that "Cyclic IMP" could be a specific term used within a certain medical context, such as in a research study or a medical specialty.

IMP is an abbreviation that can stand for several things in the medical field, including:

* Inosine Monophosphate, a nucleotide involved in the synthesis of DNA and RNA
* Imipenem, an antibiotic used to treat severe bacterial infections
* Ischemic Myocardial Pathology, a term used to describe damage to the heart muscle caused by reduced blood flow.

Without more context or information, it is difficult for me to provide a more specific definition of "Cyclic IMP." I would recommend consulting with a medical professional or checking the source where you encountered this term for further clarification.

'Dictyostelium' is a genus of social amoebae that are commonly found in soil and decaying organic matter. These microscopic organisms have a unique life cycle, starting as individual cells that feed on bacteria. When food becomes scarce, the cells undergo a developmental process where they aggregate together to form a multicellular slug-like structure called a pseudoplasmodium or grex. This grex then moves and differentiates into a fruiting body that can release spores for further reproduction.

Dictyostelium discoideum is the most well-studied species in this genus, serving as a valuable model organism for research in various fields such as cell biology, developmental biology, and evolutionary biology. The study of Dictyostelium has contributed significantly to our understanding of fundamental biological processes like chemotaxis, signal transduction, and cell differentiation.

Alkaloids are a type of naturally occurring organic compounds that contain mostly basic nitrogen atoms. They are often found in plants, and are known for their complex ring structures and diverse pharmacological activities. Many alkaloids have been used in medicine for their analgesic, anti-inflammatory, and therapeutic properties. Examples of alkaloids include morphine, quinine, nicotine, and caffeine.

Atropine is an anticholinergic drug that blocks the action of the neurotransmitter acetylcholine in the central and peripheral nervous system. It is derived from the belladonna alkaloids, which are found in plants such as deadly nightshade (Atropa belladonna), Jimson weed (Datura stramonium), and Duboisia spp.

In clinical medicine, atropine is used to reduce secretions, increase heart rate, and dilate the pupils. It is often used before surgery to dry up secretions in the mouth, throat, and lungs, and to reduce salivation during the procedure. Atropine is also used to treat certain types of nerve agent and pesticide poisoning, as well as to manage bradycardia (slow heart rate) and hypotension (low blood pressure) caused by beta-blockers or calcium channel blockers.

Atropine can have several side effects, including dry mouth, blurred vision, dizziness, confusion, and difficulty urinating. In high doses, it can cause delirium, hallucinations, and seizures. Atropine should be used with caution in patients with glaucoma, prostatic hypertrophy, or other conditions that may be exacerbated by its anticholinergic effects.

Aminopyridines are a group of organic compounds that contain an amino group (-NH2) attached to a pyridine ring, which is a six-membered aromatic heterocycle containing one nitrogen atom. Aminopyridines have various pharmacological properties and are used in the treatment of several medical conditions.

The most commonly used aminopyridines in medicine include:

1. 4-Aminopyridine (also known as Fampridine): It is a potassium channel blocker that is used to improve walking ability in patients with multiple sclerosis (MS) and other neurological disorders. It works by increasing the conduction of nerve impulses in demyelinated nerves, thereby improving muscle strength and coordination.
2. 3,4-Diaminopyridine: It is a potassium channel blocker that is used to treat Lambert-Eaton myasthenic syndrome (LEMS), a rare autoimmune disorder characterized by muscle weakness. It works by increasing the release of acetylcholine from nerve endings, thereby improving muscle strength and function.
3. 2-Aminopyridine: It is an experimental drug that has been studied for its potential use in treating various neurological disorders, including MS, Parkinson's disease, and stroke. It works by increasing the release of neurotransmitters from nerve endings, thereby improving neuronal communication.

Like all medications, aminopyridines can have side effects, including gastrointestinal symptoms, headache, dizziness, and in rare cases, seizures. It is important to use these drugs under the supervision of a healthcare provider and follow their dosage instructions carefully.

Chlorides are simple inorganic ions consisting of a single chlorine atom bonded to a single charged hydrogen ion (H+). Chloride is the most abundant anion (negatively charged ion) in the extracellular fluid in the human body. The normal range for chloride concentration in the blood is typically between 96-106 milliequivalents per liter (mEq/L).

Chlorides play a crucial role in maintaining electrical neutrality, acid-base balance, and osmotic pressure in the body. They are also essential for various physiological processes such as nerve impulse transmission, maintenance of membrane potentials, and digestion (as hydrochloric acid in the stomach).

Chloride levels can be affected by several factors, including diet, hydration status, kidney function, and certain medical conditions. Increased or decreased chloride levels can indicate various disorders, such as dehydration, kidney disease, Addison's disease, or diabetes insipidus. Therefore, monitoring chloride levels is essential for assessing a person's overall health and diagnosing potential medical issues.

The liver is a large, solid organ located in the upper right portion of the abdomen, beneath the diaphragm and above the stomach. It plays a vital role in several bodily functions, including:

1. Metabolism: The liver helps to metabolize carbohydrates, fats, and proteins from the food we eat into energy and nutrients that our bodies can use.
2. Detoxification: The liver detoxifies harmful substances in the body by breaking them down into less toxic forms or excreting them through bile.
3. Synthesis: The liver synthesizes important proteins, such as albumin and clotting factors, that are necessary for proper bodily function.
4. Storage: The liver stores glucose, vitamins, and minerals that can be released when the body needs them.
5. Bile production: The liver produces bile, a digestive juice that helps to break down fats in the small intestine.
6. Immune function: The liver plays a role in the immune system by filtering out bacteria and other harmful substances from the blood.

Overall, the liver is an essential organ that plays a critical role in maintaining overall health and well-being.

Arginine is an α-amino acid that is classified as a semi-essential or conditionally essential amino acid, depending on the developmental stage and health status of the individual. The adult human body can normally synthesize sufficient amounts of arginine to meet its needs, but there are certain circumstances, such as periods of rapid growth or injury, where the dietary intake of arginine may become necessary.

The chemical formula for arginine is C6H14N4O2. It has a molecular weight of 174.20 g/mol and a pKa value of 12.48. Arginine is a basic amino acid, which means that it contains a side chain with a positive charge at physiological pH levels. The side chain of arginine is composed of a guanidino group, which is a functional group consisting of a nitrogen atom bonded to three methyl groups.

In the body, arginine plays several important roles. It is a precursor for the synthesis of nitric oxide, a molecule that helps regulate blood flow and immune function. Arginine is also involved in the detoxification of ammonia, a waste product produced by the breakdown of proteins. Additionally, arginine can be converted into other amino acids, such as ornithine and citrulline, which are involved in various metabolic processes.

Foods that are good sources of arginine include meat, poultry, fish, dairy products, nuts, seeds, and legumes. Arginine supplements are available and may be used for a variety of purposes, such as improving exercise performance, enhancing wound healing, and boosting immune function. However, it is important to consult with a healthcare provider before taking arginine supplements, as they can interact with certain medications and have potential side effects.

The endothelium is a thin layer of simple squamous epithelial cells that lines the interior surface of blood vessels, lymphatic vessels, and heart chambers. The vascular endothelium, specifically, refers to the endothelial cells that line the blood vessels. These cells play a crucial role in maintaining vascular homeostasis by regulating vasomotor tone, coagulation, platelet activation, inflammation, and permeability of the vessel wall. They also contribute to the growth and repair of the vascular system and are involved in various pathological processes such as atherosclerosis, hypertension, and diabetes.

An oocyte, also known as an egg cell or female gamete, is a large specialized cell found in the ovary of female organisms. It contains half the number of chromosomes as a normal diploid cell, as it is the product of meiotic division. Oocytes are surrounded by follicle cells and are responsible for the production of female offspring upon fertilization with sperm. The term "oocyte" specifically refers to the immature egg cell before it reaches full maturity and is ready for fertilization, at which point it is referred to as an ovum or egg.

In medical terms, the heart is a muscular organ located in the thoracic cavity that functions as a pump to circulate blood throughout the body. It's responsible for delivering oxygen and nutrients to the tissues and removing carbon dioxide and other wastes. The human heart is divided into four chambers: two atria on the top and two ventricles on the bottom. The right side of the heart receives deoxygenated blood from the body and pumps it to the lungs, while the left side receives oxygenated blood from the lungs and pumps it out to the rest of the body. The heart's rhythmic contractions and relaxations are regulated by a complex electrical conduction system.

N-Formylmethionine Leucyl-Phenylalanine (fMLP) is not a medical condition, but rather a synthetic peptide that is often used in laboratory settings for research purposes. It is a formylated methionine residue linked to a leucine and phenylalanine tripeptide.

fMLP is a potent chemoattractant for certain types of white blood cells, including neutrophils and monocytes. When these cells encounter fMLP, they are stimulated to migrate towards the source of the peptide and release various inflammatory mediators. As such, fMLP is often used in studies of inflammation, immune cell function, and signal transduction pathways.

It's important to note that while fMLP has important research applications, it is not a substance that would be encountered or used in clinical medicine.

"Swine" is a common term used to refer to even-toed ungulates of the family Suidae, including domestic pigs and wild boars. However, in a medical context, "swine" often appears in the phrase "swine flu," which is a strain of influenza virus that typically infects pigs but can also cause illness in humans. The 2009 H1N1 pandemic was caused by a new strain of swine-origin influenza A virus, which was commonly referred to as "swine flu." It's important to note that this virus is not transmitted through eating cooked pork products; it spreads from person to person, mainly through respiratory droplets produced when an infected person coughs or sneezes.

Phosphoinositide Phospholipase C (PI-PLC) is an enzyme that plays a crucial role in intracellular signaling pathways. It catalyzes the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2), a phospholipid component of the cell membrane, into two second messengers: inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG).

IP3 is responsible for triggering the release of calcium ions from intracellular stores, while DAG remains in the membrane and activates certain protein kinase C (PKC) isoforms. These second messengers then go on to modulate various cellular processes such as gene expression, metabolism, secretion, and cell growth or differentiation. PI-PLC exists in multiple isoforms, which are classified based on their structure and activation mechanisms. They can be activated by a variety of extracellular signals, including hormones, neurotransmitters, and growth factors, making them important components in signal transduction cascades.

Indomethacin is a non-steroidal anti-inflammatory drug (NSAID) that is commonly used to reduce pain, inflammation, and fever. It works by inhibiting the activity of certain enzymes in the body, including cyclooxygenase (COX), which plays a role in producing prostaglandins, chemicals involved in the inflammatory response.

Indomethacin is available in various forms, such as capsules, suppositories, and injectable solutions, and is used to treat a wide range of conditions, including rheumatoid arthritis, osteoarthritis, ankylosing spondylitis, gout, and bursitis. It may also be used to relieve pain and reduce fever in other conditions, such as dental procedures or after surgery.

Like all NSAIDs, indomethacin can have side effects, including stomach ulcers, bleeding, and kidney damage, especially when taken at high doses or for long periods of time. It may also increase the risk of heart attack and stroke. Therefore, it is important to use indomethacin only as directed by a healthcare provider and to report any unusual symptoms or side effects promptly.

Tetradecanoylphorbol acetate (TPA) is defined as a pharmacological agent that is a derivative of the phorbol ester family. It is a potent tumor promoter and activator of protein kinase C (PKC), a group of enzymes that play a role in various cellular processes such as signal transduction, proliferation, and differentiation. TPA has been widely used in research to study PKC-mediated signaling pathways and its role in cancer development and progression. It is also used in topical treatments for skin conditions such as psoriasis.

An action potential is a brief electrical signal that travels along the membrane of a nerve cell (neuron) or muscle cell. It is initiated by a rapid, localized change in the permeability of the cell membrane to specific ions, such as sodium and potassium, resulting in a rapid influx of sodium ions and a subsequent efflux of potassium ions. This ion movement causes a brief reversal of the electrical potential across the membrane, which is known as depolarization. The action potential then propagates along the cell membrane as a wave, allowing the electrical signal to be transmitted over long distances within the body. Action potentials play a crucial role in the communication and functioning of the nervous system and muscle tissue.

Guanosine triphosphate (GTP) is a nucleotide that plays a crucial role in various cellular processes, such as protein synthesis, signal transduction, and regulation of enzymatic activities. It serves as an energy currency, similar to adenosine triphosphate (ATP), and undergoes hydrolysis to guanosine diphosphate (GDP) or guanosine monophosphate (GMP) to release energy required for these processes. GTP is also a precursor for the synthesis of other essential molecules, including RNA and certain signaling proteins. Additionally, it acts as a molecular switch in many intracellular signaling pathways by binding and activating specific GTPase proteins.

Electrophysiology is a branch of medicine that deals with the electrical activities of the body, particularly the heart. In a medical context, electrophysiology studies (EPS) are performed to assess abnormal heart rhythms (arrhythmias) and to evaluate the effectiveness of certain treatments, such as medication or pacemakers.

During an EPS, electrode catheters are inserted into the heart through blood vessels in the groin or neck. These catheters can record the electrical activity of the heart and stimulate it to help identify the source of the arrhythmia. The information gathered during the study can help doctors determine the best course of treatment for each patient.

In addition to cardiac electrophysiology, there are also other subspecialties within electrophysiology, such as neuromuscular electrophysiology, which deals with the electrical activity of the nervous system and muscles.

Oral administration is a route of giving medications or other substances by mouth. This can be in the form of tablets, capsules, liquids, pastes, or other forms that can be swallowed. Once ingested, the substance is absorbed through the gastrointestinal tract and enters the bloodstream to reach its intended target site in the body. Oral administration is a common and convenient route of medication delivery, but it may not be appropriate for all substances or in certain situations, such as when rapid onset of action is required or when the patient has difficulty swallowing.

A lung is a pair of spongy, elastic organs in the chest that work together to enable breathing. They are responsible for taking in oxygen and expelling carbon dioxide through the process of respiration. The left lung has two lobes, while the right lung has three lobes. The lungs are protected by the ribcage and are covered by a double-layered membrane called the pleura. The trachea divides into two bronchi, which further divide into smaller bronchioles, leading to millions of tiny air sacs called alveoli, where the exchange of gases occurs.

2,3'-Cyclic Nucleotide 3'-Phosphodiesterase (CNP) is an enzyme that specifically hydrolyzes 2',3'-cyclic nucleotides to 2'-nucleotide monophosphates. It plays a crucial role in regulating the levels of intracellular second messengers, such as cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP), which are involved in various cellular processes including signal transduction, gene expression, and metabolism.

CNP has two isoforms, CNP1 and CNP2, which differ in their tissue distribution and substrate specificity. CNP1 is predominantly expressed in the central nervous system (CNS) and preferentially hydrolyzes cGMP, while CNP2 is widely distributed and hydrolyzes both cGMP and cAMP with similar efficiency.

Mutations in the gene encoding CNP1 have been associated with certain neurological disorders, such as spastic paraplegia type 5 (SPG5), a hereditary condition characterized by progressive muscle weakness and stiffness in the lower limbs.

The following is a list of phosphodiesterase inhibitors. Adibendan Aminophylline Aminophylline dihydrate Amipizone Apremilast ... Udenafil Vardenafil Vardenafil dihydrochloride Vardenafil hydrochloride trihydrate Zaprinast Phosphodiesterase inhibitor This ...
A phosphodiesterase inhibitor is a drug that blocks one or more of the five subtypes of the enzyme phosphodiesterase (PDE), ... and so acts as a selective PDE4 inhibitor or a non-selective phosphodiesterase inhibitor, depending on the dose. Piclamilast, a ... is another cGMP-specific phosphodiesterase inhibitor which inhibits PDE9, a cGMP preferring phosphodiesterase. PDE9 is ... These phosphodiesterase inhibitors are used primarily as remedies for erectile dysfunction, as well as having some other ...
A phosphodiesterase-4 inhibitor, commonly referred to as a PDE4 inhibitor, is a drug used to block the degradative action of ... and so acts as a selective PDE4 inhibitor or a non-selective phosphodiesterase inhibitor, depending on the dose. Luteolin, ... "A Review of Phosphodiesterase-Inhibition and the Potential Role for Phosphodiesterase 4-Inhibitors in Clinical Dermatology" ( ... Kanes SJ, Tokarczyk J, Siegel SJ, Bilker W, Abel T, Kelly MP (2006). "Rolipram: A specific phosphodiesterase 4 inhibitor with ...
The major PDE5 inhibitors (a subset of the phosphodiesterase inhibitors) are sildenafil, tadalafil, vardenafil, and avanafil, ... Other phosphodiesterase-5 inhibitors were developed from the structure in figure 7. Although PDE5 inhibitors main use has been ... Yu, J. Y.; Kang, K. K. & Yoo, M. (2006). "Erectile potentials of a new phosphodiesterase type 5 inhibitor, DA-8159, in diet- ... McMahon, C. G.; McMahon, C. N.; Leow, L. J. & Winestock, C. G. (2006). "Efficacy of type-5 phosphodiesterase inhibitors in the ...
A phosphodiesterase type 5 inhibitor (PDE5 inhibitor) is a vasodilating drug that works by blocking the degradative action of ... As of 2019, the wider cardiovascular benefits of PDE5 inhibitors are being appreciated. Phosphodiesterase-5 (PDE5) inhibitors ... Rao AR, Thwaini A, Ahmed HU, Shergill IS, Minhas S (July 2007). "The phosphodiesterase inhibitors and non-arteritic anterior ... Rao AR, Thwaini A, Ahmed HU, Shergill IS, Minhas S (July 2007). "The phosphodiesterase inhibitors and non-arteritic anterior ...
... although it is known to be a phosphodiesterase inhibitor. It is a potent (IC50 = 36nM) inhibitor of phosphodiesterase-II.[ ... Jones GH, Venuti MC, Alvarez R, Bruno JJ, Berks AH, Prince A (February 1987). "Inhibitors of cyclic AMP phosphodiesterase. 1. ... Phosphodiesterase inhibitors, Imidazoquinazolines, Lactams, Chloroarenes, Takeda Pharmaceutical Company brands). ...
Tachyphylaxis and phosphodiesterase type 5 inhibitors. Author Steers, William D. Viability and safety of combination drug ...
Phosphodiesterase inhibitors (e.g., sildenafil) can also improve [Raynaud's phenomenon] symptoms and ulcer healing Nieto ... Laties AM (January 2009). "Vision disorders and phosphodiesterase type 5 inhibitors: a review of the evidence to date". Drug ... Sildenafil is a potent and selective inhibitor of cGMP-specific phosphodiesterase type 5 (PDE5), which is responsible for ... Roustit M, Blaise S, Allanore Y, Carpentier PH, Caglayan E, Cracowski JL (October 2013). "Phosphodiesterase-5 inhibitors for ...
1995).[full citation needed] "Phosphodiesterase Inhibitors". CV Pharmacology. Archived from the original on 13 June 2017. ... It should not be used together with medications within the PDE5 inhibitor family such as sildenafil due to the risk of low ...
Coadministration of a protease inhibitor with a PDE5 inhibitor is expected to substantially increase the PDE5 inhibitor ... Discovered by Pfizer, sildenafil is a potent and selective inhibitor of cGMP-specific phosphodiesterase type 5 (PDE5), which is ... Hutchings DC, Anderson SG, Caldwell JL, Trafford AW (March 2018). "Phosphodiesterase-5 inhibitors and the heart: compound ... Weiss B, Hait WN (1977). "Selective cyclic nucleotide phosphodiesterase inhibitors as potential therapeutic agents". Annual ...
MK-8189 - phosphodiesterase 10A inhibitor. Osoresnontrine (BI-409306, SUB-166499) - phosphodiesterase 9A inhibitor Sodium ... serotonin-norepinephrine reuptake inhibitor, uncompetitive NMDA receptor antagonist, muscarinic acetylcholine receptor agonist ... benzoate (SND-11, SND-12, SND-13, SND-14; Clozaben, NaBen) - D-amino acid oxidase inhibitor Evenamide (NW-3509; NW-3509A) - ...
Jin SL, Ding SL, Lin SC (2012-06-01). "Phosphodiesterase 4 and its inhibitors in inflammatory diseases". Chang Gung Medical ... October 2004). "Ibudilast, a nonselective phosphodiesterase inhibitor, regulates Th1/Th2 balance and NKT cell subset in ... a phosphodiesterase inhibitor, protects against white matter damage under chronic cerebral hypoperfusion in the rat". Brain ... "Neuroprotective role of phosphodiesterase inhibitor ibudilast on neuronal cell death induced by activated microglia". ...
... is a phosphodiesterase-3 inhibitor. This drug inhibits the action of phosphodiesterase-3 and thus prevents ... It is a phosphodiesterase 3 inhibitor that works to increase the heart's contractility and decrease pulmonary vascular ... Phosphodiesterases are enzymes responsible for the breakdown of cAMP. Therefore, when phosphodiesterases lower the level of ...
It acts as a selective PDE3 inhibitor. It is no longer available. Phosphodiesterase inhibitor David J. Triggle (1996). ... "Inhibition of platelet-derived growth factor-induced mitogenesis by phosphodiesterase 3 inhibitors: role of protein kinase A in ... Denis D, Riendeau D (February 1999). "Phosphodiesterase 4-dependent regulation of cyclic AMP levels and leukotriene B4 ...
... is also a phosphodiesterase inhibitor. Sulmazole is classified as an imidazopyridine and a sulfoxide. Sulmazole can ...
Ukena D, Schudt C, Sybrecht GW (February 1993). "Adenosine receptor-blocking xanthines as inhibitors of phosphodiesterase ... but as with other xanthine derivatives DPCPX also acts as a phosphodiesterase inhibitor, and is almost as potent as rolipram at ... Phosphodiesterase inhibitors, Xanthines, Cyclopentanes, Propyl compounds, All stub articles, Nervous system drug stubs). ...
Weiss, B.; Hait, W.N. (1977). "Selective cyclic nucleotide phosphodiesterase inhibitors as potential therapeutic agents". Annu ... The multiple forms of phosphodiesterase also play major roles in various biological processes. Although more than one form of ...
August 2009). "Discovery of a novel class of phosphodiesterase 10A inhibitors and identification of clinical candidate 2-[4-(1- ... November 2011). "Highly potent, selective, and orally active phosphodiesterase 10A inhibitors". Journal of Medicinal Chemistry ... and orally active phosphodiesterase 10A (PDE10A) inhibitor". Journal of Medicinal Chemistry. 57 (22): 9627-9643. doi:10.1021/ ... and efficacious inhibitor of phosphodiesterase 10A (PDE10A)". Journal of Medicinal Chemistry. 57 (15): 6632-6641. doi:10.1021/ ...
ISBN 978-1-60913-345-0. Li, Heng; Zuo, Jianping; Tang, Wei (17 October 2018). "Phosphodiesterase-4 Inhibitors for the Treatment ... "Meta-Analysis of the Relative Efficacy and Safety of Oral P2Y12 Inhibitors in Patients With Acute Coronary Syndrome". The ...
... is another cGMP-specific phosphodiesterase inhibitor which inhibits PDE9, a cGMP preferring phosphodiesterase. PDE9 is ... The potential for selective phosphodiesterase inhibitors to be used as therapeutic agents was predicted in the 1970s by Weiss ... Sildenafil (Viagra) is an inhibitor of cGMP-specific phosphodiesterase type 5, which enhances the vasodilatory effects of cGMP ... Xanthines such as caffeine and theobromine are cAMP-phosphodiesterase inhibitors. However, the inhibitory effect of xanthines ...
... is an inhibitor of phosphodiesterase 3. It has been tested in dogs for its effects on heart output and dilation of ... Dorszewski, A; Müller-Beckmann, B; Kling, L; Sponer, G (1990). "Haemodynamic profile of an inhibitor of phosphodiesterase III, ... Phosphodiesterase inhibitors, Benzimidazoles, All stub articles, Cardiovascular system drug stubs). ...
Marmar JL, Harkins TJ, Riordan J (May 2008). "Studies with Trimix gel in men who failed phosphodiesterase inhibitors". Journal ...
This mechanism is similar to that of phosphodiesterase 5 (PDE5) inhibitors such as sildenafil (Viagra) and tadalafil (Cialis), ... Kukreja RC, Salloum FN, Das A (May 2012). "Cyclic Guanosine Monophosphate Signaling and Phosphodiesterase-5 Inhibitors in ...
Huang Z, Mancini JA (2006). "Phosphodiesterase 4 inhibitors for the treatment of asthma and COPD". Curr. Med. Chem. 13 (27): ... Medicinal Chemistry of PDE4 Inhibitors. Chapter 33 in Cyclic Nucleotide Phosphodiesterases in Health and Disease, Eds Joseph A ... Rolipram is a selective phosphodiesterase-4 inhibitor discovered and developed by Schering AG as a potential antidepressant ... Rolipram continues to be used in research as a well-characterized PDE4 inhibitor.: 669 It has been used in studies to ...
Vardi M, Nini A (January 2007). "Phosphodiesterase inhibitors for erectile dysfunction in patients with diabetes mellitus". The ... The PDE5 inhibitors sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis) are prescription drugs which are taken by ... In many instances, medication-based therapies are used, specifically PDE5 inhibitors like sildenafil. These drugs function by ... the oral PDE5 inhibitor, was introduced by Pfizer in 1999. Anthropological research presents ED not as a disorder but, as a ...
s The U.S. FDA approved sildenafil, a selective inhibitor of cGMP specific phosphodiesterase type 5 (PDE5), for the treatment ... June 2004). "Nitric oxide pathway and phosphodiesterase inhibitors in pulmonary arterial hypertension". Journal of the American ... In 2009, they also approved tadalafil, another PDE5 inhibitor, marketed under the name Adcirca. PDE5 inhibitors are believed to ... A Long-Acting Phosphodiesterase-5 Inhibitor for the Treatment of Pulmonary Arterial Hypertension. 2011;33:993-1004 Galiè N, ...
Phosphodiesterase-5 (PDE-5) inhibitors are the first-line drugs indicated for erectile dysfunction (ED), implying the sustained ... Okuyucu, S; Guven, O E; Akoglu, E; Uçar, E; Dagli, S (2009). "Effect of phosphodiesterase-5 inhibitor on hearing". The Journal ... Huang, Sharon A.; Lie, Janette D. (2013). "Phosphodiesterase-5 (PDE5) Inhibitors In the Management of Erectile Dysfunction". P ... "Pre-clinical evidence for the use of phosphodiesterase-5 inhibitors for treating benign prostatic hyperplasia and lower urinary ...
... , like papaverine, acts as a phosphodiesterase inhibitor. Additionally, it has anticholinergic effects. Committee for ...
Giembycz MA (June 2005). "Life after PDE4: overcoming adverse events with dual-specificity phosphodiesterase inhibitors". Curr ... and calmodulin-dependent phosphodiesterase. It is one of the 11 families of phosphodiesterase (PDE1-PDE11). Phosphodiesterase 1 ... The phosphodiesterase 1 isozyme family belongs to a Class I enzymes, which includes all vertebrate phosphodiesterases and some ... The phosphodiesterase 1 isoenzyme family (along with the phosphodiesterase 4 family) is the most diverse one and includes ...
Phosphodiesterase inhibitors such as milrinone are sometimes utilized in severe cardiomyopathy. The mechanism of action is ... Packer M (1989). "Effect of phosphodiesterase inhibitors on survival of patients with chronic congestive heart failure". Am. J ... There is a significant evidence-practice gap in the treatment of CHF; particularly the underuse of ACE inhibitors and β- ... ACE inhibitors improve symptoms, decrease mortality and reduce ventricular hypertrophy. Angiotensin II receptor antagonist ...
The following is a list of phosphodiesterase inhibitors. Adibendan Aminophylline Aminophylline dihydrate Amipizone Apremilast ... Udenafil Vardenafil Vardenafil dihydrochloride Vardenafil hydrochloride trihydrate Zaprinast Phosphodiesterase inhibitor This ...
Phosphodiesterase-5 Enzyme Inhibitors. Class Summary. At least seven phosphodiesterase (PDE) classes are known, many with ... Phosphodiesterase type 5 (PDE5) inhibitors are the principal oral agents used in ED. ... PDE5 inhibitors rely on the role of nitric oxide (NO) in inducing vasodilatation. NO relaxes the smooth muscle of the corpora ... Available PDE5 inhibitors include sildenafil, vardenafil, tadalafil, and avanafil. These agents do not directly cause penile ...
... Vascular. 2014 Aug;22(4):313-6. doi: ... the first three reported cases of thromboangiitis obliterans successfully treated with phosphodiesterase type 5 inhibitors, ...
Phosphodiesterase-5 Enzyme Inhibitors. Class Summary. The antiproliferative effects of the phosphodiesterase type-5 (PDE5) ... Phosphodiesterase-5 inhibitor in Eisenmenger syndrome: a preliminary observational study. Circulation. 2006 Oct 24. 114(17): ... Tadalafil is a PDE5 selective inhibitor. Inhibition of PDE5 increases cGMP activity, which increases the vasodilatory effects ... may be significant in the chronic treatment of pulmonary hypertension with PDE5 inhibitors such as sildenafil. These agents act ...
Change from baseline (the last documented value while still receiving phosphodiesterase-5 inhibitor) in N-terminal prohormone ... Change from baseline (the last documented value while still receiving phosphodiesterase-5 inhibitor) in 6-min walking distance ... Change in haemodynamics from baseline (the last documented value while still receiving phosphodiesterase-5 inhibitor) to week ... A proportion of pulmonary arterial hypertension (PAH) patients do not reach treatment goals with phosphodiesterase-5 inhibitors ...
Treatment with the type IV phosphodiesterase inhibitor Ro 20-1724 protects renal and mesenteric blood flow in endotoxemic rats ... Treatment with the type IV phosphodiesterase inhibitor Ro 20-1724 protects renal and mesenteric blood flow in endotoxemic rats ... Treatment with the type IV phosphodiesterase inhibitor Ro 20-1724 protects renal and mesenteric blood flow in endotoxemic rats ... Treatment with the type IV phosphodiesterase inhibitor Ro 20-1724 protects renal and mesenteric blood flow in endotoxemic rats ...
... an oral phosphodiesterase 3 inhibitor (PDE3) could have protective effects on atrial remodeling in a canine model of AF and ... Suppression of experimental atrial fibrillation in a canine model of rapid atrial pacing by the phosphodiesterase 3 inhibitor ... The purpose of this study was designed to investigate whether cilostazol, an oral phosphodiesterase 3 inhibitor (PDE3) could ...
PDE4 inhibitors had a statistically significant risk for producing pain but reduced occurrence of atopic dermatitis ... Topical phosphodiesterase 4 (PDE4) inhibitors vs vehicle as treatment for atopic dermatitis show no differences in emergent ... Safety profile and tolerability of topical phosphodiesterase 4 inhibitors for the treatment of atopic dermatitis: a systematic ... Close more info about Topical Phosphodiesterase 4 Inhibitors Successful in Atopic Dermatitis ...
Control medicines for chronic obstructive pulmonary disease (COPD) are drugs you take to control or prevent symptoms of COPD. You must use these medicines every day for them to work well.
... Drug Safety Update. January 2017: Apremilast (Otezla ▼): risk of suicidal thoughts and ...
Basic pharmacology of phosphodiesterase type 5 inhibitors used for the medical treatment of erectile dysfunction, from the ... Drug Interactions with Phosphodiesterase Inhibitors. Nitrates:. Phosphodiesterase inhibitors potentiate the blood pressure ... PDE5 inhibitors are used for the medical treatment of erectile dysfunction. Phosphodiesterase Inhibitors and Benign Prostatic ... Contraindications of Phosphodiesterase Inhibitors. Drugs:. No concomitant therapy with nitrates or potent inhibitors of ...
Phosphodiesterase-5 Inhibitors. Phosphodiesterase-5 inhibitors selectively lower pulmonary artery pressure, with less effect on ... A phosphodiesterase inhibitor can be used if nifedipine is not available, but concurrent use of multiple pulmonary vasodilators ...
Copyright © 2023 Phosphodiesterase 4 inhibitors for pancreatic cancer cell inhibition - Powered by Customify. ...
PHOSPHODIESTERASE INHIBITORS. Phosphodiesterase inhibitors are the drugs which blocks one or more of the five subtypes of the ... A phosphodiesterase inhibitor is a drug that blocks one or more of the five subtypes of the enzyme phosphodiesterase (PDE) ... Phosphodiesterase inhibitors-5 (PDE5 inhibitors) in the management of erectile dysfunction. PT. 38, 414-419, 2013.. Kass DA, ... and so acts as a selective PDE4 inhibitor or a non-selective phosphodiesterase inhibitor, depending on the dose.. • Piclamilast ...
Antenatal maternally-administered phosphodiesterase type 5 inhibitors normalize eNOS expression in the fetal lamb model of ... Dive into the research topics of Antenatal maternally-administered phosphodiesterase type 5 inhibitors normalize eNOS ...
... allosteric inhibitor (BPN14770) would improve cognitive function and behavioral outcomes in patients with fragile X syndrome ( ... The goal of this study was to determine whether a phosphodiesterase-4D (PDE4D) ... A mouse model of Rubinstein-Taybi syndrome: defective long-term memory is ameliorated by inhibitors of phosphodiesterase 4. ... The goal of this study was to determine whether a phosphodiesterase-4D (PDE4D) allosteric inhibitor (BPN14770) would improve ...
... (A and B) Quantitative evaluation of ring amount and tube duration for HUVEC cells treated with Jurkat or ... Phosphodiesterases Choice live-attenuated influenza vaccines predicated on modifications in the polymerase genes drive back ...
7.1 CYP 3A Inhibitors 7.2 Phosphodiesterase-5 (PDE-5) Inhibitors 8 USE IN SPECIFIC POPULATIONS 8.1 Pregnancy 8.2 Lactation 8.4 ... 7.2 Phosphodiesterase-5 (PDE-5) Inhibitors. Concomitant administration of doxazosin tablets with a phosphodiesterase-5 (PDE-5) ... 7.1 CYP 3A Inhibitors. In vitro studies suggest that doxazosin is a substrate of CYP 3A4. Strong CYP3A inhibitors may increase ... Concomitant administration of doxazosin tablets with a phosphodiesterase-5 (PDE-5) inhibitor can result in additive blood ...
Novel Phosphodiesterase 9 Inhibitor for the Treatment of Heart Failure With High Selectivity ... Novel Phosphodiesterase 9 Inhibitor for the Treatment of Heart Failure Online Inquiry ... Home / Available Projects / Novel Phosphodiesterase 9 Inhibitor for the Treatment of Heart Failure ... Eleven phosphodiesterase subfamilies have been identified. Among all PDEs, PDE9 has the highest affinity for cGMP, making it an ...
Phosphodiesterase-5 inhibitors (PDE-5 inhibitors) are commonly used oral medicines for erection problems. Examples include ... Phosphodiesterase-5 inhibitors (PDE-5 inhibitors) are commonly used oral medicines for erection problems. Examples include ... Personal stories about taking phosphodiesterase-5 inhibitors. These stories are based on information gathered from health ... Personal stories about taking phosphodiesterase-5 inhibitors. These stories are based on information gathered from health ...
Effects of phosphodiesterase 5 inhibitor on pulmonary vascular reactivity in the fetal lamb. Ann Thorac Surg. 2006 Mar. 81(3): ... 9, 10] cGMP is down-regulated by phosphodiesterase 5 activity. Phosphodiesterase 5, which is abundantly expressed in lung ... Selective serotonin reuptake inhibitors (SSRIs), commonly prescribed antidepressants, have been reported to be associated with ... Therapeutic potential of RhoA/Rho kinase inhibitors in pulmonary hypertension. Br J Pharmacol. 2008 Oct. 155(4):444-54. [QxMD ...
Phosphodiesterase-5 Enzyme Inhibitors. Class Summary. The antiproliferative effects of the phosphodiesterase type-5 (PDE5) ... Phosphodiesterase-5 inhibitor in Eisenmenger syndrome: a preliminary observational study. Circulation. 2006 Oct 24. 114(17): ... Tadalafil is a PDE5 selective inhibitor. Inhibition of PDE5 increases cGMP activity, which increases the vasodilatory effects ... may be significant in the chronic treatment of pulmonary hypertension with PDE5 inhibitors such as sildenafil. These agents act ...
... efflux in response to beta-agonist and phosphodiesterase inhibitor. Primary cells isolated from CF nasal polyps gave similar ... above baseline by beta-adrenoreceptor agonists and cGI-phosphodiesterase inhibitors in transformed nasal polyp (CF-T43) cells ... The increase in 36Cl- permeability is diminished by protein kinase A inhibitors and is not mediated by an increase in ... Activation of endogenous deltaF508 cystic fibrosis transmembrane conductance regulator by phosphodiesterase inhibition J Clin ...
Fragment- and negative image-based screening of phosphodiesterase 10A inhibitors (2019) Chemical Biology and Drug Design ... Rational design, optimization, and biological evaluation of novel α-Phosphonopropionic acids as covalent inhibitors of Rab ...
All of these drugs are known as phosphodiesterase-5 (PDE5) inhibitors and are approved for treatment of ED. By blocking the PDE ... Candidates for PDE5 Inhibitors. PDE5 inhibitors are a good choice for men of any age who are in good health and who do not have ... PDE5 inhibitors can also interact with other medications. Talk to your doctor about whether PDE5 inhibitor drugs are a safe ... However, PDE5 inhibitors are not suitable for everyone. Men who take nitrate drugs for angina cannot take PDE5 inhibitors. The ...
The effects of IBMX were mimicked by rolipram, an inhibitor of the cAMP-specific phosphodiesterase IV. Mass spectrometric ... The effects of IBMX were mimicked by rolipram, an inhibitor of the cAMP-specific phosphodiesterase IV. Mass spectrometric ... The effects of IBMX were mimicked by rolipram, an inhibitor of the cAMP-specific phosphodiesterase IV. Mass spectrometric ... The effects of IBMX were mimicked by rolipram, an inhibitor of the cAMP-specific phosphodiesterase IV. Mass spectrometric ...
Phosphodiesterase Inhibitor. Roflumilast (Daliresp) is a tablet that is swallowed.. Antibiotics. Azithromycin is a tablet that ...
... By Louis Gilman August 27, 2020. # ... Phosphodiesterase 3 (PDE3) is one member of the PDE family and has two subtypes, PDE3A and PDE3B. PDE3A mainly expresses in ... FR900359 is a Gαq/11/14 Inhibitor for Melanoma and Cardiovascular Disease Research Louis Gilman August 29, 2023. ... Vemurafenib is a First-in-class B-RAF Inhibitor for Melanoma Research Louis Gilman July 25, 2023. ...
Furue, M., Kadono, T., Tsuji, G., & Nakahara, T. (2017). Topical E6005/RVT-501, a novel phosphodiesterase 4 inhibitor, for the ... Furue, M, Kadono, T, Tsuji, G & Nakahara, T 2017, Topical E6005/RVT-501, a novel phosphodiesterase 4 inhibitor, for the ... Topical E6005/RVT-501, a novel phosphodiesterase 4 inhibitor, for the treatment of atopic dermatitis. In: Expert Opinion on ... Topical E6005/RVT-501, a novel phosphodiesterase 4 inhibitor, for the treatment of atopic dermatitis. Expert Opinion on ...
Phosphodiesterase-4 Inhibitor (PDE-4 Inhibitor). A type of medication that helps control airway inflammation. It may also help ...
  • Phosphodiesterase type 5 (PDE5) inhibitors are the principal oral agents used in ED. (medscape.com)
  • PDE5 inhibitors rely on the role of nitric oxide (NO) in inducing vasodilatation. (medscape.com)
  • PDE5 inhibitors are used for the medical treatment of erectile dysfunction . (urology-textbook.com)
  • The strong treatment effect and the favorable side effect profile make PDE5 inhibitors the first choice treatment option of erectile dysfunction. (urology-textbook.com)
  • It was recognised that papaverine and pentoxifylline mediated vasorelaxation by a number of mechanisms including non-selective PDE inhibition and these drugs can be considered as forerunners to the clinically successful PDE5 inhibitors used today for the treatment of erectile dysfunction. (biomedjournal.com)
  • Men who take nitrate drugs cannot use PDE5 inhibitors. (limamemorial.org)
  • PDE5 inhibitors can also interact with other medications. (limamemorial.org)
  • In univentricular hearts, selective lung vasodilators such as phosphodiesterase type 5 (PDE5) inhibitors would decrease pulmonary resistance and improve exercise tolerance. (thechipnetwork.org)
  • However, the level of evidence for the use of PDE5 inhibitors in patients with a single ventricle (SV) remains limited. (thechipnetwork.org)
  • The SV-INHIBITION study aims to answer the question whether PDE5 inhibitors should be prescribed in patients with an SV. (thechipnetwork.org)
  • Viagra and Cialis (tadalafil) are both phosphodiesterase type 5 (PDE5) inhibitors. (healthline.com)
  • And there are multiple reports on men taking PDE5 inhibitors and exhibiting better life quality from the perspective of confidence and satisfaction. (healthline.com)
  • PDE5 inhibitors are endothelial friendly medications," Goldstein said. (healthline.com)
  • PDE5 inhibitors are contraindicated in patients taking any form of organic nitrates. (findlaw.com)
  • Tadalafil is a PDE5-selective inhibitor that is chemically unrelated to sildenafil and vardenafil. (medscape.com)
  • Tadalafil is in a class of medications called phosphodiesterase (PDE) inhibitors. (medlineplus.gov)
  • He noted that the Food and Drug Administration (FDA) had approved a daily dose of Cialis (tadalafil), another PDE5 inhibitor for ED and other uses, in January 2008. (healthline.com)
  • Symptoms that aid in the diagnosis of psychogenic ED include abrupt onset, intermittent character, loss of erection maintenance, quality nocturnal erection, and excellent response to phosphodiesterase-5 inhibitors (e.g., sildenafil, tadalafil, vardenafil). (bvsalud.org)
  • Inhibition of the phosphodiesterase type 5 causes a preponderance of the erectile signal transduction and thus an improvement in erection. (urology-textbook.com)
  • phosphodiesterase 4 inhibitors significantly elevated cAMP and enhanced alcohol-mediated inhibition of dust-stimulated TNF-a release. (cdc.gov)
  • Degerman E, in 't Zandt R, Pålbrink A, Eliasson L, Caye-Thomasen P, Magnusson M. Inhibition of Phosphodiesterase 3, 4 and 5 induces endolymphatic hydrops in mouse inner ear, as evaluated with repeated 9.4T MRI. (lu.se)
  • The purpose of this study was designed to investigate whether cilostazol, an oral phosphodiesterase 3 inhibitor (PDE3) could have protective effects on atrial remodeling in a canine model of AF and explore the potential molecular mechanisms. (physiciansweekly.com)
  • PDE3 inhibitors can be thought of as a backdoor approach to cardiac stimulation, whereas β-agonists go through the front door to produce the same cardiac effects. (biomedjournal.com)
  • PDE3 was identified as a potential therapeutic target in cardiovascular disease and asthma, and indeed, PDE3 inhibitors have subsequently been shown to relax vascular and airway smooth muscle, inhibit platelet aggregation and induce lipolysis. (biomedjournal.com)
  • Phosphodiesterase 3 ( PDE3 ) is one member of the PDE family and has two subtypes, PDE3A and PDE3B. (cancer-research-network.com)
  • PDE3 inhibitors suppress meiosis in oocytes by decreasing the level of cAMP and blocking the extrusion of the first polar body. (cancer-research-network.com)
  • A proportion of pulmonary arterial hypertension (PAH) patients do not reach treatment goals with phosphodiesterase-5 inhibitors (PDE5i). (ersjournals.com)
  • All phosphodiesterase inhibitors for the treatment of erectile dysfunction inhibit potent and highly specific the type 5 phosphodiesterase. (urology-textbook.com)
  • [ 5 ] Nitroglycerin is contraindicated in patients who are allergic to it and in patients who are taking phosphodiesterase inhibitors for erectile dysfunction. (medscape.com)
  • BioLink2022 is a highly selective oral PDE9 small molecule inhibitor in early clinical development for the treatment of chronic heart failure. (protheragen.com)
  • Phosphodiesterase inhibitors potentiate the blood pressure lowering effects of nitrates. (urology-textbook.com)
  • Co-administration of nitrates and phosphodiesterase inhibitors is contraindicated. (urology-textbook.com)
  • By increasing our understanding of the physiological roles of the individual PDE isoforms, in parallel with the development of even more selective inhibitors of these enzymes, it is highly likely that better therapeutically active drugs will emerge. (biomedjournal.com)
  • The potential activity for selective phosphodiesterase inhibitors as therapeutic agents was predicted as early as 1977 by Weiss and Hait (Weiss and Hait, 1977). (biomedjournal.com)
  • The active ingredients of Poxet-60 tablets is Dapoxetine 60mg , a Selective Serotonin Reuptake Inhibitor (SSRI) that specifically treats Premature Ejaculation (PE), as it works quickly and gives results within two hours and is quickly discharged from the body within a period of 24 hours. (pde-5.com)
  • The active ingredient of Poxet-60 tablets is a selective serotonin reuptake inhibitor (SSRI) known as Dapoxetine, that treats and prevents the recurrence or persistence of PE. (pde-5.com)
  • Prezcobix (darunavir and cobicistat) is a combination of a human immunodeficiency virus ( HIV -1) protease inhibitor and a CYP3A inhibitor and is indicated for the treatment of HIV-1 infection in adult patients. (rxlist.com)
  • As [HA565 trade name] is used as a pharmacokinetic enhancer with other protease inhibitors, the product information for the particular protease inhibitor must be consulted. (who.int)
  • The recommended dose is 100 mg ritonavir once or two times per day, depending on the concurrently used protease inhibitor. (who.int)
  • For children who are undergoing anti-tuberculosis treatment with rifampicin, higher dosages of ritonavir may be needed for pharmacokinetic enhancement of the combined protease inhibitor. (who.int)
  • Depending on the specific protease inhibitor with which it is co-administered, ritonavir may be appropriate for use with caution in patients with renal insufficiency. (who.int)
  • For specific dosing information in patients with renal impairment, refer to the product information of the co-administered protease inhibitor. (who.int)
  • In the absence of pharmacokinetic studies in patients with stable severe hepatic impairment (Child Pugh grade C) without decompensation, caution should be exercised when ritonavir is used as a pharmacokinetic enhancer as increased levels of the co-administered protease inhibitor may occur. (who.int)
  • Specific recommendations for use of ritonavir as a pharmacokinetic enhancer in patients with hepatic impairment are dependent on the protease inhibitor with which it is co-administered. (who.int)
  • In addition, the NO synthase inhibitor, l-NMMA, also reversed the alcohol-blocking effect on dust-stimulated TNF-a. (cdc.gov)
  • Concomitant administration of doxazosin tablets with a phosphodiesterase-5 (PDE-5) inhibitor can result in additive blood pressure lowering effects and symptomatic hypotension. (nih.gov)
  • Strong cytochrome P450 (CYP) 3A inhibitors may increase exposure to doxazosin and increased risk of hypotension. (nih.gov)
  • Cobicistat is a mechanism-based inhibitor of cytochrome P450 (CYP) enzymes of the CYP3A family. (rxlist.com)
  • Researchers sought to investigate the safety and tolerability of topical PDE4 inhibitors vs vehicle in treating atopic dermatitis. (dermatologyadvisor.com)
  • Topical phosphodiesterase 4 (PDE4) inhibitors vs vehicle as treatment for atopic dermatitis show no differences in emergent adverse events or the occurrence of serious emergent adverse events, according to data from a review and meta-analysis published in Current Therapeutic Research, Clinical and Experimental . (dermatologyadvisor.com)
  • PDE4 inhibitors showed a statistically significant reduced occurrence of exacerbation in atopic dermatitis and a significant risk for producing pain in studies with a low risk for bias. (dermatologyadvisor.com)
  • Researchers concluded that, "PDE4 inhibitors did not show differences from vehicle treatment in treatment emergent adverse events or serious emergent adverse events incidence. (dermatologyadvisor.com)
  • Initiation of new COPD therapy, including a methylxanthine preparation, maintenance macrolide therapy, and/or phosphodiesterase 4 (PDE4) inhibitor is not permitted within 4 weeks prior to Visit 1. (who.int)
  • Avanafil is a PDE5 inhibitor that inhibits cGMP degradation and thereby enhances the effects of NO in smooth muscle relaxation of the corpus cavernosum. (medscape.com)
  • The homeostatic role of phosphodiesterases (PDEs) as related to the intracellular levels of cAMP and cGMP was first described by Sutherland (Sutherland, Rall, 1958) who, due to this, was awarded the Nobel Prize for Physiology and Medicine in 1971. (biomedjournal.com)
  • Phosphodiesterases (PDEs) hydrolyze the phosphodiester bond of cAMP and cGMP to form the inactive 5′-AMP and 5′-GMP. (biomedjournal.com)
  • Phosphodiesterase 9 (PDE9), a specifically hydrolytic enzyme with the highest affinity for cyclic guanosine monophosphate (cGMP) among the phosphodiesterase family, controls cGMP in cardiac myocytes and is strongly upregulated in human heart failure, suggesting its potential as a promising therapeutic target in heart failure. (protheragen.com)
  • The family of phosphodiesterases (PDEs) are regulatory hydrolase enzymes that play a crucial role in modulating cyclic nucleotides, including cGMP and cAMP, which are involved in a wide range of physiological processes. (protheragen.com)
  • Among all PDEs, PDE9 has the highest affinity for cGMP, making it an attractive target for inhibitors that regulate cGMP levels. (protheragen.com)
  • Talk to your doctor about whether PDE5 inhibitor drugs are a safe choice for you. (limamemorial.org)
  • It is a potent PDE9 inhibitor that characterized by high selectivity, low brain penetration, and target tissue distribution. (protheragen.com)
  • The structures reveal their novel mode of action as competitive ligands for the binding site of an incoming DNA substrate, and point the way to generating novel and potent inhibitors of TDP2. (rcsb.org)
  • We have found that, 36Cl- efflux can be stimulated 19-61% above baseline by beta-adrenoreceptor agonists and cGI-phosphodiesterase inhibitors in transformed nasal polyp (CF-T43) cells homozygous for the deltaF508 mutation. (nih.gov)
  • Phosphodiesterase inhibitors (PDIs) have important vascular and myocardial protective effects and thus have shown therapeutic usefulness in the clinical settings for treatment of patients with heart failure, pulmonary hypertension, and coronary artery disease. (biomedjournal.com)
  • Coadministration of nonspecific PDE-5 inhibitors (eg, dipyridamole, theophylline) and guanylate cyclase stimulators (eg, riociguat) is contraindicated due to risk of additive hypotension. (medscape.com)
  • Increased orthostatic hypotension with simultaneous administration of alpha blocker and phosphodiesterase inhibitors may occur. (urology-textbook.com)
  • The goal of this study was to determine whether a phosphodiesterase-4D (PDE4D) allosteric inhibitor (BPN14770) would improve cognitive function and behavioral outcomes in patients with fragile X syndrome (FXS). (nature.com)
  • Introduction: Local adverse effects of steroid use and the burning sensation of calcineurin inhibitors impair patients' adherence to treatment and decrease the treatment response in atopic dermatitis (AD). (elsevierpure.com)
  • HA565 trade name] is indicated as a pharmacokinetic enhancer for protease inhibitors when these are used in combination therapy with other antiretroviral agents for the treatment of HIV-1 infected patients. (who.int)
  • [ 6 ] Patients should not have taken a phosphodiesterase inhibitor for at least 48 hours before the exam. (medscape.com)
  • Strong CYP and P-gp/BCRP inhibitors: For patients receiving strong CYP and P-gp/BCRP inhibitors, consider a starting dose of 0.5 mg three times a day. (globalrph.com)
  • However, some patients report that they experienced serious side effects, including cardiovascular issues after taking PDE-5 inhibitors. (findlaw.com)
  • The increase in 36Cl- permeability is diminished by protein kinase A inhibitors and is not mediated by an increase in intracellular calcium concentrations. (nih.gov)
  • Substantial studies indicate that icariin may be beneficial to AD by reducing the production of extracellular amyloid plaques and intracellular neurofibrillary tangles and inhibiting phosphodiesterase-5 activity. (frontiersin.org)
  • We present the first three reported cases of thromboangiitis obliterans successfully treated with phosphodiesterase type 5 inhibitors, followed by a discussion of the rationale for the use of these agents in thromboangiitis obliterans. (nih.gov)
  • Treatment with the type IV phosphodiesterase inhibitor Ro 20-1724 protects renal and mesenteric blood flow in endotoxemic rats treated with norepinephrine. (aspetjournals.org)
  • Smooth muscle of the prostate and urinary bladder also express type 4 and type 5 phosphodiesterase. (urology-textbook.com)
  • The phosphodiesterase type 5 plays a crucial role in the inactivation of the signal transduction for the penile erection . (urology-textbook.com)
  • Phosphodiesterase type 5 inhibitors: the day after. (urology-textbook.com)
  • Technically, Levitra is considered an oral phosphodiesterase type-5 inhibitor. (findlaw.com)
  • Rarely clinically significant cardiac arrhythmia, angina pectoris or cardiac death (the causality of phosphodiesterase inhibitors in cardiac death is difficult to assess). (urology-textbook.com)
  • In the current study, the β-adrenergic receptor agonist isoproterenol, alone or in combination with the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX), was used to increase cAMP in neutrophils. (arizona.edu)
  • The soluble adenylyl cyclase inhibitor, KH7, however, significantly increased the inflammatory response to hog barn dust. (cdc.gov)
  • To delineate these effects, we used PKA pathway inhibitors (adenylyl cyclase [AC], cAMP, and PKA) to modulate the effects of alcohol on dust-stimulated TNF-a release in the bronchial epithelial cell line, BEAS-2B. (cdc.gov)
  • At least seven phosphodiesterase (PDE) classes are known, many with subtypes identified by structure and function. (medscape.com)
  • A phosphodiesterase inhibitor is a drug that blocks one or more of the five subtypes of the enzyme phosphodiesterase (PDE) selectively in the brain. (biomedjournal.com)
  • Table 1 summarizes the functions of each PDE and the cardiovascular effects of specific inhibitors. (biomedjournal.com)
  • The effects of IBMX were mimicked by rolipram, an inhibitor of the cAMP-specific phosphodiesterase IV. (arizona.edu)
  • The following HIV-1 protease inhibitors can be used with ritonavir as a pharmacokinetic enhancer at the noted doses. (who.int)
  • Please refer to the product information of the protease inhibitors approved for co-administration with ritonavir. (who.int)
  • Phosphodiesterase-5 inhibitors (PDE-5 inhibitors) are commonly used oral medicines for erection problems. (healthlinkbc.ca)
  • Tyrosyl-DNA phosphodiesterase 2 (TDP2) is a 5'-tyrosyl DNA phosphodiesterase important for the repair of DNA adducts generated by non-productive (abortive) activity of topoisomerase II (TOP2). (rcsb.org)
  • Darunavir is an inhibitor of the human immunodeficiency virus ( HIV -1) protease . (rxlist.com)