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.
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.
A subtype of ADENOSINE RECEPTOR that is found expressed in a variety of tissues including the BRAIN and DORSAL HORN NEURONS. The receptor is generally considered to be coupled to the GI, INHIBITORY G-PROTEIN which causes down regulation of CYCLIC AMP.
An enzyme that catalyzes the hydrolysis of ADENOSINE to INOSINE with the elimination of AMMONIA.
A subtype of ADENOSINE RECEPTOR that is found expressed in a variety of locations including the BRAIN and endocrine tissues. The receptor is generally considered to be coupled to the GI, INHIBITORY G-PROTEIN which causes down regulation of CYCLIC AMP.
A subclass of adenosine A2 receptors found in the CECUM, the COLON, the BLADDER, and a variety of other tissues. It is generally considered to be a low affinity receptor for ADENOSINE that couples to the GS, STIMULATORY G-PROTEIN.
An enzyme that catalyzes the formation of ADP plus AMP from adenosine plus ATP. It can serve as a salvage mechanism for returning adenosine to nucleic acids. EC 2.7.1.20.
A subclass of ADENOSINE RECEPTORS that are generally considered to be coupled to the GS, STIMULATORY G-PROTEIN which causes up regulation of CYCLIC AMP.
Compounds that selectively bind to and activate ADENOSINE A2 RECEPTORS.
Compounds that selectively bind to and block the activation of ADENOSINE A2 RECEPTORS.
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).
Compounds that bind to and block the stimulation of ADENOSINE A1 RECEPTORS.
Compounds that bind to and stimulate ADENOSINE A1 RECEPTORS.
Compounds that bind to and block the stimulation of PURINERGIC P1 RECEPTORS.
Purine bases found in body tissues and fluids and in some plants.
Compounds that bind to and stimulate PURINERGIC P1 RECEPTORS.
Adenine nucleotide containing one phosphate group esterified to the sugar moiety in the 2'-, 3'-, or 5'-position.
A stable adenosine A1 and A2 receptor agonist. Experimentally, it inhibits cAMP and cGMP phosphodiesterase activity.
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 selectively bind to and block the activation of ADENOSINE A3 RECEPTORS.
Cell surface proteins that bind PURINES with high affinity and trigger intracellular changes which influence the behavior of cells. The best characterized classes of purinergic receptors in mammals are the P1 receptors, which prefer ADENOSINE, and the P2 receptors, which prefer ATP or ADP.
Drugs that selectively bind to and activate ADENOSINE A3 RECEPTORS.
2-Chloroadenosine. A metabolically stable analog of adenosine which acts as an adenosine receptor agonist. The compound has a potent effect on the peripheral and central nervous system.
A group of compounds that are derivatives of beta- aminoethylbenzene which is structurally and pharmacologically related to amphetamine. (From Merck Index, 11th ed)
N-Isopropyl-N-phenyl-adenosine. Antilipemic agent. Synonym: TH 162.
A purine nucleoside that has hypoxanthine linked by the N9 nitrogen to the C1 carbon of ribose. It is an intermediate in the degradation of purines and purine nucleosides to uric acid and in pathways of purine salvage. It also occurs in the anticodon of certain transfer RNA molecules. (Dorland, 28th ed)
A glycoprotein enzyme present in various organs and in many cells. The enzyme catalyzes the hydrolysis of a 5'-ribonucleotide to a ribonucleoside and orthophosphate in the presence of water. It is cation-dependent and exists in a membrane-bound and soluble form. EC 3.1.3.5.
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.
A group of enzymes which catalyze the hydrolysis of ATP. The hydrolysis reaction is usually coupled with another function such as transporting Ca(2+) across a membrane. These enzymes may be dependent on Ca(2+), Mg(2+), anions, H+, or DNA.
An antibiotic purine ribonucleoside that readily substitutes for adenosine in the biological system, but its incorporation into DNA and RNA has an inhibitory effect on the metabolism of these nucleic acids.
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.
Catalyze the hydrolysis of nucleosides with the elimination of ammonia.
A ribonucleoside antibiotic synergist and adenosine deaminase inhibitor isolated from Nocardia interforma and Streptomyces kaniharaensis. It is proposed as an antineoplastic synergist and immunosuppressant.
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)
3,7-Dimethylxanthine. The principle alkaloid in Theobroma cacao (the cacao bean) and other plants. A xanthine alkaloid that is used as a bronchodilator and as a vasodilator. It has a weaker diuretic activity than THEOPHYLLINE and is also a less powerful stimulant of smooth muscle. It has practically no stimulant effect on the central nervous system. It was formerly used as a diuretic and in the treatment of angina pectoris and hypertension. (From Martindale, The Extra Pharmacopoeia, 30th ed, pp1318-9)
A potent inhibitor of ADENOSINE DEAMINASE. The drug induces APOPTOSIS of LYMPHOCYTES, and is used in the treatment of many lymphoproliferative malignancies, particularly HAIRY CELL LEUKEMIA. It is also synergistic with some other antineoplastic agents and has immunosuppressive activity.
5'-Adenylic acid, monoanhydride with sulfuric acid. The initial compound formed by the action of ATP sulfurylase on sulfate ions after sulfate uptake. Synonyms: adenosine sulfatophosphate; APS.
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.
Sulfhydryl analog of INOSINE that inhibits nucleoside transport across erythrocyte plasma membranes, and has immunosuppressive properties. It has been used similarly to MERCAPTOPURINE in the treatment of leukemia. (From Martindale, The Extra Pharmacopoeia, 30th ed, p503)
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.
A purine base and a fundamental unit of ADENINE NUCLEOTIDES.
Adenosine molecules which can be substituted in any position, but are lacking one hydroxyl group in the ribose part of the molecule.
Drugs that bind to and block the activation of PURINERGIC RECEPTORS.
The rate dynamics in chemical or physical systems.
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.
Drugs used to cause dilation of the blood vessels.
The relationship between the dose of an administered drug and the response of the organism to the drug.
Proteins involved in the transport of NUCLEOSIDES across cellular membranes.
A purine and a reaction intermediate in the metabolism of adenosine and in the formation of nucleic acids by the salvage pathway.
A class of enzymes that catalyze the conversion of a nucleotide and water to a nucleoside and orthophosphate. EC 3.1.3.-.
Purine bases related to hypoxanthine, an intermediate product of uric acid synthesis and a breakdown product of adenine catabolism.
Triazoles are a class of antifungal drugs that contain a triazole ring in their chemical structure and work by inhibiting the synthesis of ergosterol, an essential component of fungal cell membranes, thereby disrupting the integrity and function of the membrane.
Purine or pyrimidine bases attached to a ribose or deoxyribose. (From King & Stansfield, A Dictionary of Genetics, 4th ed)
A calcium-activated enzyme that catalyzes the hydrolysis of ATP to yield AMP and orthophosphate. It can also act on ADP and other nucleoside triphosphates and diphosphates. EC 3.6.1.5.
The circulation of blood through the CORONARY VESSELS of the HEART.
An enzyme of the lyase class that catalyzes the formation of CYCLIC AMP and pyrophosphate from ATP. EC 4.6.1.1.
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)
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 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.
Nucleosides in which the purine or pyrimidine base is combined with ribose. (Dorland, 28th ed)
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.
An enzyme which catalyzes the catabolism of S-ADENOSYLHOMOCYSTEINE to ADENOSINE and HOMOCYSTEINE. It may play a role in regulating the concentration of intracellular adenosylhomocysteine.
A class of cell surface receptors for PURINES that prefer ATP or ADP over ADENOSINE. P2 purinergic receptors are widespread in the periphery and in the central and peripheral nervous system.
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.
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 strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.
The monomeric units from which DNA or RNA polymers are constructed. They consist of a purine or pyrimidine base, a pentose sugar, and a phosphate group. (From King & Stansfield, A Dictionary of Genetics, 4th ed)
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 long-acting derivative of cyclic AMP. It is an activator of cyclic AMP-dependent protein kinase, but resistant to degradation by cyclic AMP phosphodiesterase.
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 metallic element that has the atomic symbol Mg, atomic number 12, and atomic weight 24.31. It is important for the activity of many enzymes, especially those involved in OXIDATIVE PHOSPHORYLATION.
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.
Interstitial space between cells, occupied by INTERSTITIAL FLUID as well as amorphous and fibrous substances. For organisms with a CELL WALL, the extracellular space includes everything outside of the CELL MEMBRANE including the PERIPLASM and the cell wall.
The presence of an increased amount of blood in a body part or an organ leading to congestion or engorgement of blood vessels. Hyperemia can be due to increase of blood flow into the area (active or arterial), or due to obstruction of outflow of blood from the area (passive or venous).
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
The physiological widening of BLOOD VESSELS by relaxing the underlying VASCULAR SMOOTH MUSCLE.
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.
Norbornanes are a class of bicyclic organic compounds consisting of a hydrocarbon skeleton made up of two fused 5-membered rings, where five of the six ring carbons are bonded to hydrogens and one is bonded to two additional carbon atoms, forming a bridge between the rings.
Elements of limited time intervals, contributing to particular results or situations.
Treatment process involving the injection of fluid into an organ or tissue.
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.
5'-S-(3-Amino-3-carboxypropyl)-5'-thioadenosine. Formed from S-adenosylmethionine after transmethylation reactions.
Purines with a RIBOSE attached that can be phosphorylated to PURINE NUCLEOTIDES.
Quantitative determination of receptor (binding) proteins in body fluids or tissue using radioactively labeled binding reagents (e.g., antibodies, intracellular receptors, plasma binders).
A group of compounds which consist of a nucleotide molecule to which an additional nucleoside is attached through the phosphate molecule(s). The nucleotide can contain any number of phosphates.
Compounds which inhibit or antagonize the biosynthesis or actions of phosphodiesterases.
A process that changes the nucleotide sequence of mRNA from that of the DNA template encoding it. Some major classes of RNA editing are as follows: 1, the conversion of cytosine to uracil in mRNA; 2, the addition of variable number of guanines at pre-determined sites; and 3, the addition and deletion of uracils, templated by guide-RNAs (RNA, GUIDE).
A subtype of equilibrative nucleoside transporter proteins that is sensitive to inhibition by 4-nitrobenzylthioinosine.
Inhibitor of phosphodiesterases.
Esters formed between the aldehydic carbon of sugars and the terminal phosphate of adenosine diphosphate.
Nucleotides in which the base moiety is substituted with one or more sulfur atoms.
Compounds that bind to and block the stimulation of PURINERGIC P2 RECEPTORS.
A purine nucleoside that has guanine linked by its N9 nitrogen to the C1 carbon of ribose. It is a component of ribonucleic acid and its nucleotides play important roles in metabolism. (From Dorland, 28th ed)
Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.
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.
The hollow, muscular organ that maintains the circulation of the blood.
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.
A subtype of equilibrative nucleoside transporter proteins that is insensitive to inhibition by 4-nitrobenzylthioinosine.
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 rather large group of enzymes comprising not only those transferring phosphate but also diphosphate, nucleotidyl residues, and others. These have also been subdivided according to the acceptor group. (From Enzyme Nomenclature, 1992) EC 2.7.
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.
An antidiabetic sulfonylurea derivative with actions similar to those of chlorpropamide.
The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.
A polyanionic compound with an unknown mechanism of action. It is used parenterally in the treatment of African trypanosomiasis and it has been used clinically with diethylcarbamazine to kill the adult Onchocerca. (From AMA Drug Evaluations Annual, 1992, p1643) It has also been shown to have potent antineoplastic properties.
Established cell cultures that have the potential to propagate indefinitely.
Relatively complete absence of oxygen in one or more tissues.
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.
Pyrazolopyrimidine ribonucleosides isolated from Nocardia interforma. They are antineoplastic antibiotics with cytostatic properties.
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.
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.
An enzyme that catalyzes the reaction between a purine nucleoside and orthophosphate to form a free purine plus ribose-5-phosphate. EC 2.4.2.1.
The veins and arteries of the HEART.
An enzyme that catalyzes the deamination of AMP to IMP. EC 3.5.4.6.
Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.
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 that bind to and stimulate PURINERGIC P2 RECEPTORS.
Exposure of myocardial tissue to brief, repeated periods of vascular occlusion in order to render the myocardium resistant to the deleterious effects of ISCHEMIA or REPERFUSION. The period of pre-exposure and the number of times the tissue is exposed to ischemia and reperfusion vary, the average being 3 to 5 minutes.
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 pentose active in biological systems usually in its D-form.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
Coronary vasodilator with some antiarrhythmic activity.
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)
Uridine 5'-(tetrahydrogen triphosphate). A uracil nucleotide containing three phosphate groups esterified to the sugar moiety.
Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors. These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids.
Inbred C57BL mice are a strain of laboratory mice that have been produced by many generations of brother-sister matings, resulting in a high degree of genetic uniformity and homozygosity, making them widely used for biomedical research, including studies on genetics, immunology, cancer, and neuroscience.
A dideoxynucleoside compound in which the 3'-hydroxy group on the sugar moiety has been replaced by a hydrogen. This modification prevents the formation of phosphodiester linkages which are needed for the completion of nucleic acid chains. The compound is an inhibitor of HIV replication, acting as a chain-terminator of viral DNA by binding to reverse transcriptase. Its principal side effect is nephrotoxicity. In vivo, dideoxyadenosine is rapidly metabolized to DIDANOSINE (ddI) by enzymatic deamination; ddI is then converted to dideoxyinosine monophosphate and ultimately to dideoxyadenosine triphosphate, the putative active metabolite.
N(6)-[delta(3)-isopentenyl]adenosine. Isopentenyl derivative of adenosine which is a member of the cytokinin family of plant growth regulators.
The decrease 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.

Control of glutamatergic neurotransmission in the rat spinal dorsal horn by the nucleoside transporter ENT1. (1/439)

Adenosine modulates nociceptive processing in the superficial dorsal horn of the spinal cord. In other tissues, membrane transporters influence profoundly the extracellular levels of adenosine. To investigate the putative role of nucleoside transporters in the regulation of excitatory synaptic transmission in the dorsal horn, we employed immunohistochemistry and whole-cell patch-clamp recording of substantia gelatinosa neurons in slices of rat spinal cord in vitro. The rat equilibrative nucleoside transporter (rENT1) was revealed by antibody staining to be abundant in neonatal and mature dorsal horn, especially within laminae I-III. This was confirmed by immunoblots of dorsal horn homogenate. Nitrobenzylthioinosine (NBMPR), a potent non-transportable inhibitor of rENT1, attenuated synaptically evoked EPSCs onto lamina II neurons in a concentration-dependent manner. Application of an adenosine A1 antagonist 1,3-dipropyl-8-cyclopentylxanthine produced a parallel rightward shift in the NBMPR concentration-effect curve. The effects of NBMPR were partially reversed by adenosine deaminase, which facilitates the metabolic degradation of adenosine. The modulation by NBMPR of evoked EPSCs was mimicked by exogenous adenosine or the selective A1 receptor agonist, 2-chloro-N6-cyclopentyl adenosine. NBMPR reduced the frequency but not the amplitude of spontaneous miniature EPSCs and increased the paired-pulse ratio of evoked currents, an effect that is consistent with presynaptic modulation. These data provide the first direct evidence that nucleoside transporters are able to critically modulate glutamatergic synaptic transmission.  (+info)

Ischaemic tolerance in aged mouse myocardium: the role of adenosine and effects of A1 adenosine receptor overexpression. (2/439)

The genesis of the ischaemia intolerant phenotype in aged myocardium is poorly understood. We tested the hypothesis that impaired adenosine-mediated protection contributes to ischaemic intolerance, and examined whether this is countered by A1 adenosine receptor (A1AR) overexpression. Responses to 20 min ischaemia and 45 min reperfusion were assessed in perfused hearts from young (2-4 months) and moderately aged (16-18 months) mice. Post-ischaemic contractility was impaired by ageing with elevated ventricular diastolic (32 +/- 2 vs. 18 +/- 2 mmHg in young) and reduced developed (37 +/- 3 vs. 83 +/- 6 mmHg in young) pressures. Lactate dehydrogenase (LDH) loss was exaggerated (27 +/- 2 vs. 16 +/- 2 IU g-1 in young) whereas the incidence of tachyarrhythmias was similar in young (15 +/- 1 %) and aged hearts (16 +/- 1 %). Functional analysis confirmed equipotent effects of 50 micro M adenosine at A1 and A2 receptors in young and aged hearts. Nonetheless, while 50 micro M adenosine improved diastolic (5 +/- 1 mmHg) and developed pressures (134 +/- 7 mmHg) and LDH loss (6 +/- 2 IU g-1) in young hearts, it did not alter these variables in the aged group. Adenosine did attenuate arrhythmogenesis for both ages (to ~10 %). In contrast to adenosine, 50 micro M diazoxide reduced ischaemic damage and arrhythmogenesis for both ages. Contractile and anti-necrotic effects of adenosine were limited by 100 micro M 5-hydroxydecanoate (5-HD) and 3 micro M chelerythrine. Anti-arrhythmic effects were limited by 5-HD but not chelerythrine. Non-selective (100 micro M 8-sulfophenyltheophylline) and A1-selective (150 nM 8-cyclopentyl-1,3-dipropylxanthine) adenosine receptor antagonism impaired ischaemic tolerance in young but not aged hearts. Quantitative real-time PCR and radioligand analysis indicated that impaired protection is unrelated to changes in A1AR mRNA transcription, or receptor density (~8 fmol mg-1 protein in both age groups). However, A1AR overexpression improved tolerance for both ages, restoring adenosine-mediated protection. These data reveal impaired protection via exogenous and endogenous adenosine contributes to ischaemic intolerance with ageing. This is independent of A1AR expression, and involves ineffective activation of a 5-HD-/diazoxide-sensitive process. The effects of A1AR overexpression indicate that the age-related failure in signalling can be overcome.  (+info)

Hypersensitivity of pulmonary C fibers induced by adenosine in anesthetized rats. (3/439)

Compelling clinical evidence implicates the potential role of adenosine in development of airway hyperresponsiveness and suggests involvement of pulmonary sensory receptors. This study was carried out to determine the effect of a low dose of adenosine infusion on sensitivity of pulmonary C-fiber afferents in anesthetized open-chest rats. Infusion of adenosine (40 microg x kg-1x min-1 i.v. for 90 s) mildly elevated baseline activity of pulmonary C fibers. However, during adenosine infusion, pulmonary C-fiber responses to chemical stimulants and lung inflation (30 cmH2O tracheal pressure) were markedly potentiated; e.g., the response to right atrial injection of capsaicin (0.25 or 0.5 microg/kg) was increased by more than fivefold (change in fiber activity = 2.64 +/- 0.67 and 16.27 +/- 3.11 impulses/s at control and during adenosine infusion, n = 13, P < 0.05), and this enhanced response returned to control in approximately 10 min. The potentiating effect of adenosine infusion was completely blocked by pretreatment with 8-cyclopentyl-1,3-dipropylxanthine (100 microg/kg), a selective antagonist of the adenosine A1 receptor, but was not affected by 3,7-dimethyl-1-propargylxanthine (1 mg/kg), an A2-receptor antagonist, or 3-ethyl-5-benzyl-2-methyl-4-phenylethynyl-6-phenyl-1,4-(+/-)-dihydropyridine-3,5- dicarboxylate (2 mg/kg), an A3-receptor antagonist. This potentiating effect was also mimicked by N6-cyclopentyladenosine (0.25 microg x kg-1 x min-1 for 90 s), a selective agonist of the adenosine A1 receptor. In conclusion, our results showed that infusion of adenosine significantly elevated the sensitivity of pulmonary C-fiber afferents in rat lungs and that this potentiating effect is likely mediated through activation of the adenosine A1 receptor.  (+info)

A role of protein kinase C mu in signalling from the human adenosine A1 receptor to the nucleus. (4/439)

1 Stimulation of adenosine A(1) receptors produced a stimulation of c-fos promoter-regulated gene transcription in Chinese hamster ovary (CHO)-A1 cells expressing the human A(1) receptor. Gene transcription was monitored using a luciferase-based reporter gene (pGL3). 2 This response to the A(1) receptor agonist N(6)-cyclopentyladenosine (CPA) was sensitive to inhibition by pertussis toxin, the MEK-1 inhibitor PD 98059 and by the phosphatidylinositol-3-kinase inhibitors wortmannin and LY 294002. The response was also completely abolished by the protein kinase C (PKC) inhibitor Ro-31-8220. 3 Several isoforms of PKC can be detected in CHO-A1 cells (alpha, delta, epsilon, micro, iota, zeta), but only PKC alpha, PKC delta and PKC were downregulated by prolonged treatment with phorbol ester. The c-fos-regulated luciferase response to A(1) agonists was not, however, inhibited by 24 h pretreatment with the phorbol esters phorbol 12,13-dibutyrate (PDBu). This observation, together with the fact that a significant attenuation (40%) of the c-fos-luciferase response to PDBu and A(1) agonist was produced by low concentrations of the PKC inhibitor Go 6976 suggests a role for PKC micro. 4 Stimulation of CHO-A1 cells with CPA stimulated the activation of endogenous PKC micro as measured by autophosphorylation. This was rapid, occurred within 1-2 min, but returned to basal levels after 30 min. Furthermore, transient expression of a constitutively active form of PKC micro resulted in a significant increase in c-fos-regulated gene expression. 5 Taken together, these data suggest that PKC micro plays an important role in the ability of the adenosine A(1) receptor to signal to the nucleus.  (+info)

Diadenosine-5-phosphate exerts A1-receptor-mediated proarrhythmic effects in rabbit atrial myocardium. (5/439)

(1) Diadenosine polyphosphates have been described to be present in the myocardium and exert purinergic- and nonreceptor-mediated effects. Since the electrophysiological properties of atrial myocardium are effectively regulated by A(1) receptors, we investigated the effect of diadenosine pentaphosphate (Ap(5)A) in rabbit myocardium. (2) Parameters of supraventricular electrophysiology and atrial vulnerability were measured in Langendorff-perfused rabbit hearts. Muscarinic potassium current (I(K(ACh/Ado))) and ATP-sensitive potassium current (I(K(ATP))) were measured by using the whole-cell voltage clamp method. (3) Ap(5)A prolonged the cycle length of spontaneously beating Langendorff perfused hearts from 225+/-14 (control) to 1823+/-400 ms (Ap(5)A 50 micro M; n=6; P<0.05). This effect was paralleled by higher degree of atrio-ventricular block. Atrial effective refractory period (AERP) in control hearts was 84+/-14 ms (n=6). Ap(5)A>/=1 micro M reduced AERP (100 micro M, 58+/-11 ms; n=6). (4) Extrastimuli delivered to hearts perfused with Ap(5)A- or adenosine (>/= micro M)-induced atrial fibrillation, the incidence of which correlated to the concentration added to the perfusate. The selective A(1)-receptor antagonist CPX (20 micro M) inhibited the Ap(5)A- and adenosine-induced decrease of AERP. Atrial fibrillation was no longer observed in the presence of CPX. (5) The described Ap(5)A-induced effects in the multicellular preparation were enhanced by dipyridamole (10 micro M), which is a cellular adenosine uptake inhibitor. Dipyridamole-induced enhancement was inhibited by CPX. (6) Ap(5)A (+info)

Comparison of effects of MgCl2 and Gpp(NH)p on antagonist and agonist radioligand binding to adenosine A1 receptors. (6/439)

AIM: To investigate modulation of antagonist and agonist binding to adenosine A1 receptors by MgCl2 and 5 -guanylimidodiphosphate (Gpp(NH)p) using rat brain membranes and the A1 antagonist [3H]-8-cyclopentyl-1,3-dipropylxanthine ([3H]DPCPX) and the A1 agonist [3H]-2-chloro-N6-cyclopentyladenosine ([3H]CCPA). METHODS: Parallel saturation and inhibition studies were performed using well-characterised radioligand binding assays and a Brandel Cell Harvester. RESULTS: MgCl2 produced a concentration-dependent decrease (44%), whereas Gpp(NH)p increased [3H]DPCPX binding (19%). In [3H]DPCPX competition studies, agonist affinity was 1.5-14.6-fold higher and 4.6-10-fold lower in the presence of 10 mmol/L MgCl2 and 10 micromol/L Gpp(NH)p respectively; antagonist affinity was unaffected. The decrease in agonist affinity with increasing Gpp(NH)p concentrations was due to a reduction in the proportion of binding to the high affinity receptor state. In contrast to [3H]DPCPX, MgCl2 produced a concentration-dependent increase (72%) and Gpp(NH)p a decrease (85%) in [3H]CCPA binding. Using [3H]CCPA, agonist affinities were 5-17-fold higher than those for [3H]DPCPX, consistent with binding only to the high affinity receptor state. Agonist affinity was 1.3-10.5-fold higher and 2.4-4.7-fold lower on adding MgCl2 or Gpp(NH)p respectively; antagonist affinities were as for [3H]DPCPX. CONCLUSION: The inconsistencies surrounding the effects of MgCl2 and guanine nucleotides on radioligand binding to adenosine A1 receptors were systematically examined. The effects of MgCl2 and Gpp(NH)p on agonist binding to A1 receptors are consistent with their roles in stimulating GTP-hydrolysis at the G-protein alpha-subunit and in blocking formation of the high affinity agonist-receptor-G protein complex.  (+info)

Adenosine A(1) receptor-mediated presynaptic inhibition at the calyx of Held of immature rats. (7/439)

At the calyx of Held synapse in brainstem slices of 5- to 7-day-old (P5-7) rats, adenosine, or the type 1 adenosine (A1) receptor agonist N6-cyclopentyladenosine (CPA), inhibited excitatory postsynaptic currents (EPSCs) without affecting the amplitude of miniature EPSCs. The A1 receptor antagonist 8-cyclopentyltheophylline (CPT) had no effect on the amplitude of EPSCs evoked at a low frequency, but significantly reduced the magnitude of synaptic depression caused by repetitive stimulation at 10 Hz, suggesting that endogenous adenosine is involved in the regulation of transmitter release. Adenosine inhibited presynaptic Ca(2+) currents (IpCa) recorded directly from calyceal terminals, but had no effect on presynaptic K+ currents. When EPSCs were evoked by IpCa during simultaneous pre- and postsynaptic recordings, the magnitude of the adenosine-induced inhibition of IpCa fully explained that of EPSCs, suggesting that the presynaptic Ca(2+) channel is the main target of A1 receptors. Whereas the N-type Ca(2+) channel blocker omega-conotoxin attenuated EPSCs, it had no effect on the magnitude of adenosine-induced inhibition of EPSCs. During postnatal development, in parallel with a decrease in the A1 receptor immunoreactivity at the calyceal terminal, the inhibitory effect of adenosine became weaker. We conclude that presynaptic A1 receptors at the immature calyx of Held synapse play a regulatory role in transmitter release during high frequency transmission, by inhibiting multiple types of presynaptic Ca(2+) channels.  (+info)

Brief, repeated, oxygen-glucose deprivation episodes protect neurotransmission from a longer ischemic episode in the in vitro hippocampus: role of adenosine receptors. (8/439)

1. Ischemic preconditioning in the brain consists of reducing the sensitivity of neuronal tissue to further, more severe, ischemic insults. We recorded field epsps (fepsps) extracellularly from hippocampal slices to develop a model of in vitro ischemic preconditioning and to evaluate the role of A1, A2A and A3 adenosine receptors in this phenomenon. 2. The application of an ischemic insult, obtained by glucose and oxygen deprivation for 7 min, produced an irreversible depression of synaptic transmission. Ischemic preconditioning was induced by four ischemic insults (2 min each) separated by 13 min of normoxic conditions. After 30 min, an ischemic insult of 7 min was applied. This protocol substantially protected the tissue from the irreversible depression of synaptic activity. 3. The selective adenosine A1 receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, 100 nm), completely prevented the protective effect of preconditioning. The selective adenosine A2A receptor antagonist 4-(2-[7-amino-2-(2-furyl)[1,2,4]triazolo[2,3-a][1,3,5]triazin-5-ylamino]ethyl)phe nol (ZM 241385, 100 nm) did not modify the magnitude of fepsp recovery compared to control slices. The selective A3 adenosine receptor antagonists, 3-propyl-6-ethyl-5[ethyl(thio)carbonyl]-2-phenyl-4-propyl-3-pyridinecarboxylate (MRS 1523, 100 nm) significantly improved the recovery of fepsps after 7 min of ischemia. 4. Our results show that in vitro ischemic preconditioning allows CA1 hippocampal neurons to become resistant to prolonged exposure to ischemia. Adenosine, by stimulating A1 receptors, plays a crucial role in eliciting the cell mechanisms underlying preconditioning; A2A receptors are not involved in this phenomenon, whereas A3 receptor activation is harmful to ischemic preconditioning.  (+info)

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.

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.

Adenosine A1 receptor is a type of G protein-coupled receptor that binds to the endogenous purine nucleoside adenosine. When activated, it inhibits the production of cyclic AMP (cAMP) in the cell by inhibiting adenylyl cyclase activity. This results in various physiological effects, such as decreased heart rate and reduced force of heart contractions, increased potassium conductance, and decreased calcium currents. The Adenosine A1 receptor is widely distributed throughout the body, including the brain, heart, kidneys, and other organs. It plays a crucial role in various biological processes, including cardiovascular function, neuroprotection, and inflammation.

Adenosine Deaminase (ADA) is an enzyme that plays a crucial role in the immune system by helping to regulate the levels of certain chemicals called purines within cells. Specifically, ADA helps to break down adenosine, a type of purine, into another compound called inosine. This enzyme is found in all tissues of the body, but it is especially active in the immune system's white blood cells, where it helps to support their growth, development, and function.

ADA deficiency is a rare genetic disorder that can lead to severe combined immunodeficiency (SCID), a condition in which babies are born with little or no functional immune system. This makes them extremely vulnerable to infections, which can be life-threatening. ADA deficiency can be treated with enzyme replacement therapy, bone marrow transplantation, or gene therapy.

Adenosine A3 receptor (A3R) is a type of G-protein coupled receptor that binds to adenosine, a purine nucleoside, and plays a role in various physiological processes. The activation of A3R leads to the inhibition of adenylate cyclase activity, which results in decreased levels of intracellular cAMP. This, in turn, modulates several downstream signaling pathways that are involved in anti-inflammatory and neuroprotective effects.

A3R is widely expressed in various tissues, including the brain, heart, lungs, liver, kidneys, and immune cells. In the central nervous system, A3R activation has been shown to have neuroprotective effects, such as reducing glutamate release, protecting against excitotoxicity, and modulating neuroinflammation. Additionally, A3R agonists have been investigated for their potential therapeutic benefits in various pathological conditions, including pain management, ischemia-reperfusion injury, and neurodegenerative diseases.

Overall, the Adenosine A3 receptor is an important target for drug development due to its role in modulating inflammation and cellular responses in various tissues and diseases.

Adenosine A2B receptor (A2BAR) is a type of G protein-coupled receptor that binds the endogenous purine nucleoside adenosine. It is a subtype of the A2 class of adenosine receptors, which also includes A2A receptor.

The A2BAR is widely expressed in various tissues and cells, including vascular smooth muscle cells, endothelial cells, fibroblasts, immune cells, and epithelial cells. Activation of the A2BAR by adenosine leads to a variety of cellular responses, such as relaxation of vascular smooth muscle, inhibition of platelet aggregation, modulation of inflammatory responses, and stimulation of fibroblast proliferation and collagen production.

The A2BAR has been implicated in several physiological and pathophysiological processes, such as cardiovascular function, pain perception, neuroprotection, tumor growth and metastasis, and pulmonary fibrosis. Therefore, the development of selective A2BAR agonists or antagonists has been an area of active research for therapeutic interventions in these conditions.

Adenosine kinase (ADK) is an enzyme that plays a crucial role in the regulation of adenosine levels in cells. The medical definition of adenosine kinase is:

"An enzyme (EC 2.7.1.20) that catalyzes the phosphorylation of adenosine to form adenosine monophosphate (AMP) using ATP as the phosphate donor. This reaction helps maintain the balance between adenosine and its corresponding nucleotides in cells, and it plays a significant role in purine metabolism, cell signaling, and energy homeostasis."

Adenosine kinase is widely distributed in various tissues, including the brain, heart, liver, and muscles. Dysregulation of adenosine kinase activity has been implicated in several pathological conditions, such as ischemia-reperfusion injury, neurodegenerative disorders, and cancer. Therefore, modulating adenosine kinase activity has emerged as a potential therapeutic strategy for treating these diseases.

Adenosine A2 receptors are a type of G-protein coupled receptor that binds the endogenous purine nucleoside adenosine. They are divided into two subtypes, A2a and A2b, which have different distributions in the body and couple to different G proteins.

A2a receptors are found in high levels in the brain, particularly in the striatum, and play a role in regulating the release of neurotransmitters such as dopamine and glutamate. They also have anti-inflammatory effects and are being studied as potential targets for the treatment of neurological disorders such as Parkinson's disease and multiple sclerosis.

A2b receptors, on the other hand, are found in a variety of tissues including the lung, blood vessels, and immune cells. They play a role in regulating inflammation and vasodilation, and have been implicated in the development of conditions such as asthma and pulmonary fibrosis.

Both A2a and A2b receptors are activated by adenosine, which is released in response to cellular stress or injury. Activation of these receptors can lead to a variety of downstream effects, depending on the tissue and context in which they are expressed.

Adenosine A2 receptor agonists are pharmaceutical agents that bind to and activate the A2 subtype of adenosine receptors, which are G-protein coupled receptors found in various tissues throughout the body. Activation of these receptors leads to a variety of physiological effects, including vasodilation, increased coronary blood flow, and inhibition of platelet aggregation.

A2 receptor agonists have been studied for their potential therapeutic benefits in several medical conditions, such as:

1. Heart failure: A2 receptor agonists can improve cardiac function and reduce symptoms in patients with heart failure by increasing coronary blood flow and reducing oxygen demand.
2. Atrial fibrillation: These agents have been shown to terminate or prevent atrial fibrillation, a common abnormal heart rhythm disorder, through their effects on the electrical properties of cardiac cells.
3. Asthma and COPD: A2 receptor agonists can help relax airway smooth muscle and reduce inflammation in patients with asthma and chronic obstructive pulmonary disease (COPD).
4. Pain management: Some A2 receptor agonists have been found to have analgesic properties, making them potential candidates for pain relief in various clinical settings.

Examples of A2 receptor agonists include regadenoson, which is used as a pharmacological stress agent during myocardial perfusion imaging, and dipyridamole, which is used to prevent blood clots in patients with certain heart conditions. However, it's important to note that these agents can have side effects, such as hypotension, bradycardia, and bronchoconstriction, so their use must be carefully monitored and managed by healthcare professionals.

Adenosine A2 receptor antagonists are a class of pharmaceutical compounds that block the action of adenosine at A2 receptors. Adenosine is a naturally occurring molecule in the body that acts as a neurotransmitter and has various physiological effects, including vasodilation and inhibition of heart rate.

Adenosine A2 receptor antagonists work by binding to A2 receptors and preventing adenosine from activating them. This results in the opposite effect of adenosine, leading to vasoconstriction and increased heart rate. These drugs are used for a variety of medical conditions, including asthma, chronic obstructive pulmonary disease (COPD), and heart failure.

Examples of Adenosine A2 receptor antagonists include theophylline, caffeine, and some newer drugs such asistradefylline and tozadenant. These drugs have different pharmacological properties and are used for specific medical conditions. It is important to note that adenosine A2 receptor antagonists can have side effects, including restlessness, insomnia, and gastrointestinal symptoms, and should be used under the guidance of a healthcare professional.

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.

Adenosine A1 receptor antagonists are a class of pharmaceutical compounds that block the action of adenosine at A1 receptors. Adenosine is a naturally occurring purine nucleoside that acts as a neurotransmitter and modulator of various physiological processes, including cardiovascular function, neuronal excitability, and immune response.

Adenosine exerts its effects by binding to specific receptors on the surface of cells, including A1, A2A, A2B, and A3 receptors. The activation of A1 receptors leads to a variety of physiological responses, such as vasodilation, negative chronotropy (slowing of heart rate), and negative inotropy (reduced contractility) of the heart, as well as inhibition of neurotransmitter release in the brain.

Adenosine A1 receptor antagonists work by binding to and blocking the action of adenosine at A1 receptors, thereby preventing or reducing its effects on these physiological processes. These drugs have been investigated for their potential therapeutic uses in various conditions, such as heart failure, cardiac arrest, and neurological disorders.

Examples of adenosine A1 receptor antagonists include:

* Dipyridamole: a vasodilator used to treat peripheral arterial disease and to prevent blood clots.
* Caffeine: a natural stimulant found in coffee, tea, and chocolate, which acts as a weak A1 receptor antagonist.
* Rolofylline: an experimental drug that has been investigated for its potential use in treating acute ischemic stroke and traumatic brain injury.
* KW-3902: another experimental drug that has been studied for its potential therapeutic effects in heart failure, cardiac arrest, and neurodegenerative disorders.

It's important to note that adenosine A1 receptor antagonists may have side effects and potential risks, and their use should be monitored and managed by healthcare professionals.

Adenosine A1 receptor agonists are medications or substances that bind to and activate the adenosine A1 receptors, which are found on the surface of certain cells in the body, including those in the heart, brain, and other organs.

Adenosine is a naturally occurring molecule in the body that helps regulate various physiological processes, such as cardiovascular function and neurotransmission. The adenosine A1 receptor plays an important role in modulating the activity of the heart, including reducing heart rate and lowering blood pressure.

Adenosine A1 receptor agonists are used clinically to treat certain medical conditions, such as supraventricular tachycardia (a rapid heart rhythm originating from above the ventricles), and to prevent cerebral vasospasm (narrowing of blood vessels in the brain) following subarachnoid hemorrhage.

Examples of adenosine A1 receptor agonists include adenosine, regadenoson, and capadenoson. These medications work by mimicking the effects of naturally occurring adenosine on the A1 receptors, leading to a decrease in heart rate and blood pressure.

It's important to note that adenosine A1 receptor agonists can have side effects, such as chest pain, shortness of breath, and flushing, which are usually transient and mild. However, they should be used with caution and under the supervision of a healthcare professional, as they can also have more serious side effects in certain individuals.

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.

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.

Purinergic P1 receptor agonists are substances that bind to and activate purinergic P1 receptors, which are a type of G protein-coupled receptor found in many tissues throughout the body. These receptors are activated by endogenous nucleotides such as adenosine and its metabolites.

Purinergic P1 receptors include four subtypes: A1, A2A, A2B, and A3. Each of these subtypes has distinct signaling pathways and physiological roles. For example, A1 receptor activation can lead to vasodilation, bradycardia, and anti-inflammatory effects, while A2A receptor activation can increase cyclic AMP levels and have anti-inflammatory effects.

Purinergic P1 receptor agonists are used in various therapeutic applications, including as cardiovascular drugs, antiplatelet agents, and anti-inflammatory agents. Some examples of purinergic P1 receptor agonists include adenosine, regadenoson, and dipyridamole.

It's important to note that the use of these substances should be under medical supervision due to their potential side effects and interactions with other medications.

Adenosine monophosphate (AMP) is a nucleotide that is the monophosphate ester of adenosine, consisting of the nitrogenous base adenine attached to the 1' carbon atom of ribose via a β-N9-glycosidic bond, which in turn is esterified to a phosphate group. It is an important molecule in biological systems as it plays a key role in cellular energy transfer and storage, serving as a precursor to other nucleotides such as ADP and ATP. AMP is also involved in various signaling pathways and can act as a neurotransmitter in the central nervous system.

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.

Adenosine A3 receptor antagonists are a class of pharmaceutical compounds that block the action of adenosine at the A3 receptor. Adenosine is a naturally occurring purine nucleoside that acts as a neurotransmitter and modulator of various physiological processes, including cardiovascular function, immune response, and neuromodulation.

The A3 receptor is one of four subtypes of adenosine receptors (A1, A2A, A2B, and A3) that are widely distributed throughout the body. The activation of A3 receptors has been implicated in a variety of pathological conditions, including inflammation, pain, ischemia-reperfusion injury, and cancer.

Adenosine A3 receptor antagonists have been investigated as potential therapeutic agents for various diseases, such as rheumatoid arthritis, chronic pain, ischemic heart disease, and cancer. These compounds work by preventing the binding of adenosine to its receptor, thereby blocking its downstream signaling pathways.

Some examples of Adenosine A3 receptor antagonists include:

* MRS1523
* MRE-2029F20
* LUF5834
* VUF5574
* OT-7962

It is important to note that while Adenosine A3 receptor antagonists have shown promise in preclinical studies, their clinical efficacy and safety profile are still being evaluated in ongoing research.

Purinergic receptors are a type of cell surface receptor that bind and respond to purines and pyrimidines, which are nucleotides and nucleosides. These receptors are involved in various physiological processes, including neurotransmission, muscle contraction, and inflammation. There are two main types of purinergic receptors: P1 receptors, which are activated by adenosine, and P2 receptors, which are activated by ATP and other nucleotides.

P2 receptors are further divided into two subtypes: P2X and P2Y. P2X receptors are ionotropic receptors that form cation channels upon activation, allowing the flow of ions such as calcium and sodium into the cell. P2Y receptors, on the other hand, are metabotropic receptors that activate G proteins upon activation, leading to the activation or inhibition of various intracellular signaling pathways.

Purinergic receptors have been found to play a role in many diseases and conditions, including neurological disorders, cardiovascular disease, and cancer. They are also being studied as potential targets for drug development.

Adenosine A3 receptor agonists are a type of pharmaceutical compound that bind to and activate the adenosine A3 receptor, which is a type of G-protein coupled receptor found in various tissues throughout the body. Activation of the A3 receptor has been shown to have anti-inflammatory and analgesic effects, making it a target for the development of drugs to treat conditions such as rheumatoid arthritis, inflammatory bowel disease, and chronic pain. Examples of adenosine A3 receptor agonists include IB-MECA, Cl-IB-MECA, and MRS1523.

2-Chloroadenosine is a synthetic, chlorinated analog of adenosine, which is a naturally occurring purine nucleoside. It acts as an antagonist at adenosine receptors and has been studied for its potential effects on the cardiovascular system, including its ability to reduce heart rate and blood pressure. It may also have anti-cancer properties and has been investigated as a potential therapeutic agent in cancer treatment. However, further research is needed to establish its safety and efficacy in clinical settings.

Phenethylamines are a class of organic compounds that share a common structural feature, which is a phenethyl group (a phenyl ring bonded to an ethylamine chain). In the context of pharmacology and neuroscience, "phenethylamines" often refers to a specific group of psychoactive drugs, including stimulants like amphetamine and mescaline, a classic psychedelic. These compounds exert their effects by modulating the activity of neurotransmitters in the brain, such as dopamine, norepinephrine, and serotonin. It is important to note that many phenethylamines have potential for abuse and are controlled substances.

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.

Inosine is not a medical condition but a naturally occurring compound called a nucleoside, which is formed from the combination of hypoxanthine and ribose. It is an intermediate in the metabolic pathways of purine nucleotides, which are essential components of DNA and RNA. Inosine has been studied for its potential therapeutic benefits in various medical conditions, including neurodegenerative disorders, cardiovascular diseases, and cancer. However, more research is needed to fully understand its mechanisms and clinical applications.

5'-Nucleotidase is an enzyme that is found on the outer surface of cell membranes, including those of liver cells and red blood cells. Its primary function is to catalyze the hydrolysis of nucleoside monophosphates, such as adenosine monophosphate (AMP) and guanosine monophosphate (GMP), to their corresponding nucleosides, such as adenosine and guanosine, by removing a phosphate group from the 5' position of the nucleotide.

Abnormal levels of 5'-Nucleotidase in the blood can be indicative of liver or bone disease. For example, elevated levels of this enzyme in the blood may suggest liver damage or injury, such as that caused by hepatitis, cirrhosis, or alcohol abuse. Conversely, low levels of 5'-Nucleotidase may be associated with certain types of anemia, including aplastic anemia and paroxysmal nocturnal hemoglobinuria.

Medical professionals may order a 5'-Nucleotidase test to help diagnose or monitor the progression of these conditions. It is important to note that other factors, such as medication use or muscle damage, can also affect 5'-Nucleotidase levels, so results must be interpreted in conjunction with other clinical findings and diagnostic tests.

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.

Adenosine triphosphatases (ATPases) are a group of enzymes that catalyze the conversion of adenosine triphosphate (ATP) into adenosine diphosphate (ADP) and inorganic phosphate. This reaction releases energy, which is used to drive various cellular processes such as muscle contraction, transport of ions across membranes, and synthesis of proteins and nucleic acids.

ATPases are classified into several types based on their structure, function, and mechanism of action. Some examples include:

1. P-type ATPases: These ATPases form a phosphorylated intermediate during the reaction cycle and are involved in the transport of ions across membranes, such as the sodium-potassium pump and calcium pumps.
2. F-type ATPases: These ATPases are found in mitochondria, chloroplasts, and bacteria, and are responsible for generating a proton gradient across the membrane, which is used to synthesize ATP.
3. V-type ATPases: These ATPases are found in vacuolar membranes and endomembranes, and are involved in acidification of intracellular compartments.
4. A-type ATPases: These ATPases are found in the plasma membrane and are involved in various functions such as cell signaling and ion transport.

Overall, ATPases play a crucial role in maintaining the energy balance of cells and regulating various physiological processes.

Tubercidin is not a medical term itself, but it is a type of antibiotic that belongs to the class of compounds known as nucleoside antibiotics. Specifically, tubercidin is a naturally occurring adenine analogue that is produced by several species of Streptomyces bacteria.

Tubercidin has been found to have antimicrobial and antitumor activities. It works by inhibiting the enzyme adenosine deaminase, which plays a crucial role in the metabolism of nucleotides in cells. By inhibiting this enzyme, tubercidin can interfere with DNA and RNA synthesis, leading to cell death.

While tubercidin has shown promise as an anticancer agent in preclinical studies, its clinical use is limited due to its toxicity and potential for causing mutations in normal cells. Therefore, it is primarily used for research purposes to study the mechanisms of nucleotide metabolism and the effects of nucleoside analogues on cell growth and differentiation.

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.

Nucleoside deaminases are a group of enzymes that catalyze the removal of an amino group (-NH2) from nucleosides, converting them to nucleosides with a modified base. This modification process is called deamination. Specifically, these enzymes convert cytidine and adenosine to uridine and inosine, respectively. Nucleoside deaminases play crucial roles in various biological processes, including the regulation of gene expression, immune response, and nucleic acid metabolism. Some nucleoside deaminases are also involved in the development of certain diseases and are considered as targets for drug design and discovery.

Coformycin is an antimetabolite antibiotic, which means it interferes with the growth of bacteria by inhibiting the synthesis of nucleic acids, the genetic material of bacteria. It is derived from Streptomyces coelicolor and is used primarily in research to study bacterial metabolism.

Coformycin is a potent inhibitor of bacterial enzyme adenosine deaminase, which is involved in purine biosynthesis. By inhibiting this enzyme, Coformycin prevents the bacteria from synthesizing the building blocks needed to make DNA and RNA, thereby inhibiting their growth.

Coformycin has not been approved for use as a therapeutic drug in humans or animals due to its narrow spectrum of activity and potential toxicity. However, it is still used in research settings to study bacterial metabolism and the mechanisms of antibiotic resistance.

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.

Theobromine is defined as a bitter, crystalline alkaloid of the cacao plant, and is found in chocolate, especially cocoa. It is a stimulant that primarily affects the heart and cardiovascular system, and to a lesser extent the central nervous system. Theobromine is also found in the kola nut and tea leaves.

In a medical context, theobromine may be used as a vasodilator and diuretic. It can help to relax muscles, widen blood vessels, and increase urine production. However, it is important to note that theobromine is toxic to some animals, including dogs and cats, and can cause serious medical problems or even death if ingested in large quantities.

Pentostatin is a medication used in the treatment of certain types of cancer, including hairy cell leukemia and certain T-cell lymphomas. It is a type of drug called a purine nucleoside analog, which works by interfering with the production of DNA and RNA, the genetic material found in cells. This can help to stop the growth and multiplication of cancer cells.

Pentostatin is given intravenously (through an IV) in a healthcare setting, such as a hospital or clinic. It is usually administered on a schedule of every other week. Common side effects of pentostatin include nausea, vomiting, diarrhea, and loss of appetite. It can also cause more serious side effects, such as low blood cell counts, infections, and liver problems.

It's important to note that this is a medical definition of the drug and its use, and it should not be used as a substitute for professional medical advice. If you have any questions about pentostatin or your treatment, it is best to speak with your healthcare provider.

Adenosine phosphosulfate (APS) is a biological compound that plays a crucial role in the sulfur metabolism of many organisms. It is an activated form of sulfate, which means it is ready to be used in various biochemical reactions. APS consists of adenosine monophosphate (AMP), a molecule related to adenosine triphosphate (ATP), linked to a sulfate group through a phosphate bridge.

In the human body, APS is primarily produced in the liver and is involved in the synthesis of the amino acids cysteine and methionine, which contain sulfur atoms. These amino acids are essential for various biological processes, including protein synthesis, antioxidant defense, and detoxification.

APS is also a key intermediate in the bacterial process of dissimilatory sulfate reduction, where sulfate is reduced to hydrogen sulfide (H2S) as a terminal electron acceptor during anaerobic respiration. This process is important for the global sulfur cycle and the ecology of anaerobic environments.

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.

Thioinosine is not a medical term itself, but it is a chemical compound that has been studied in the field of medical research. Thioinosine is an analogue of the nucleoside inosine, where the oxygen atom in the heterocyclic ring is replaced by a sulfur atom.

In the context of medical research, thioinosine has been investigated for its potential immunomodulatory and antiviral properties. It has been studied as an inhibitor of certain enzymes involved in the replication of viruses, such as HIV and hepatitis C virus. However, it is not currently approved for use as a medication in clinical practice.

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.

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.

Deoxyadenosine is a chemical compound that is a component of DNA, one of the nucleic acids that make up the genetic material of living organisms. Specifically, deoxyadenosine is a nucleoside, which is a molecule consisting of a sugar (in this case, deoxyribose) bonded to a nitrogenous base (in this case, adenine).

Deoxyribonucleosides like deoxyadenosine are the building blocks of DNA, along with phosphate groups. In DNA, deoxyadenosine pairs with thymidine via hydrogen bonds to form one of the four rungs in the twisted ladder structure of the double helix.

It is important to note that there is a similar compound called adenosine, which contains an extra oxygen atom on the sugar molecule (making it a ribonucleoside) and is a component of RNA, another nucleic acid involved in protein synthesis and other cellular processes.

Purinergic antagonists are a class of drugs that block the action of purinergic receptors, which are specialized proteins found on the surface of cells that respond to purines such as ATP and ADP. These receptors play important roles in various physiological processes, including neurotransmission, inflammation, and cell death.

Purinergic antagonists work by binding to these receptors and preventing them from being activated by purines. This can have a variety of effects depending on the specific receptor that is blocked. For example, some purinergic antagonists are used in the treatment of conditions such as chronic pain, depression, and Parkinson's disease because they block receptors that play a role in these conditions.

It's important to note that while purinergic antagonists can be useful therapeutically, they can also have side effects and potential risks. As with any medication, it's important to use them only under the guidance of a healthcare professional.

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.

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.

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.

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.

Nucleoside transport proteins (NTTs) are membrane-bound proteins responsible for the facilitated diffusion of nucleosides and related deoxynucleosides across the cell membrane. These proteins play a crucial role in the uptake of nucleosides, which serve as precursors for DNA and RNA synthesis, as well as for the salvage of nucleotides in the cell.

There are two main types of NTTs: concentrative (or sodium-dependent) nucleoside transporters (CNTs) and equilibrative (or sodium-independent) nucleoside transporters (ENTs). CNTs mainly facilitate the uptake of nucleosides against a concentration gradient, using the energy derived from the sodium ion gradient. In contrast, ENTs mediate bidirectional transport, allowing for the equalization of intracellular and extracellular nucleoside concentrations.

Nucleoside transport proteins have been identified in various organisms, including humans, and are involved in numerous physiological processes, such as cell proliferation, differentiation, and survival. Dysregulation of NTTs has been implicated in several pathological conditions, including cancer and viral infections, making them potential targets for therapeutic intervention.

Hypoxanthine is a purine derivative and an intermediate in the metabolic pathways of nucleotide degradation, specifically adenosine to uric acid in humans. It is formed from the oxidation of xanthine by the enzyme xanthine oxidase. In the body, hypoxanthine is converted to xanthine and then to uric acid, which is excreted in the urine. Increased levels of hypoxanthine in the body can be indicative of various pathological conditions, including tissue hypoxia, ischemia, and necrosis.

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.

Hypoxanthine is not a medical condition but a purine base that is a component of many organic compounds, including nucleotides and nucleic acids, which are the building blocks of DNA and RNA. In the body, hypoxanthine is produced as a byproduct of normal cellular metabolism and is converted to xanthine and then uric acid, which is excreted in the urine.

However, abnormally high levels of hypoxanthine in the body can indicate tissue damage or disease. For example, during intense exercise or hypoxia (low oxygen levels), cells may break down ATP (adenosine triphosphate) rapidly, releasing large amounts of hypoxanthine. Similarly, in some genetic disorders such as Lesch-Nyhan syndrome, there is an accumulation of hypoxanthine due to a deficiency of the enzyme that converts it to xanthine. High levels of hypoxanthine can lead to the formation of kidney stones and other complications.

Triazoles are a class of antifungal medications that have broad-spectrum activity against various fungi, including yeasts, molds, and dermatophytes. They work by inhibiting the synthesis of ergosterol, an essential component of fungal cell membranes, leading to increased permeability and disruption of fungal growth. Triazoles are commonly used in both systemic and topical formulations for the treatment of various fungal infections, such as candidiasis, aspergillosis, cryptococcosis, and dermatophytoses. Some examples of triazole antifungals include fluconazole, itraconazole, voriconazole, and posaconazole.

A nucleoside is a biochemical molecule that consists of a pentose sugar (a type of simple sugar with five carbon atoms) covalently linked to a nitrogenous base. The nitrogenous base can be one of several types, including adenine, guanine, cytosine, thymine, or uracil. Nucleosides are important components of nucleic acids, such as DNA and RNA, which are the genetic materials found in cells. They play a crucial role in various biological processes, including cell division, protein synthesis, and gene expression.

Apyrase is an enzyme that catalyzes the hydrolysis of nucleoside triphosphates (like ATP or GTP) to nucleoside diphosphates (like ADP or GDP), releasing inorganic phosphate in the process. It can also hydrolyze nucleoside diphosphates to nucleoside monophosphates, releasing inorganic pyrophosphate.

This enzyme is widely distributed in nature and has been found in various organisms, including bacteria, plants, and animals. In humans, apyrases are present in different tissues, such as the brain, platelets, and red blood cells. They play essential roles in several biological processes, including signal transduction, metabolism regulation, and inflammatory response modulation.

There are two major classes of apyrases: type I (also known as nucleoside diphosphate kinase) and type II (also known as NTPDase). Type II apyrases have higher substrate specificity for nucleoside triphosphates, while type I apyrases can hydrolyze both nucleoside tri- and diphosphates.

In the medical field, apyrases are sometimes used in research to study platelet function or neurotransmission, as they can help regulate purinergic signaling by controlling extracellular levels of ATP and ADP. Additionally, some studies suggest that apyrase activity might be involved in certain pathological conditions, such as atherosclerosis, thrombosis, and neurological disorders.

Coronary circulation refers to the circulation of blood in the coronary vessels, which supply oxygenated blood to the heart muscle (myocardium) and drain deoxygenated blood from it. The coronary circulation system includes two main coronary arteries - the left main coronary artery and the right coronary artery - that branch off from the aorta just above the aortic valve. These arteries further divide into smaller branches, which supply blood to different regions of the heart muscle.

The left main coronary artery divides into two branches: the left anterior descending (LAD) artery and the left circumflex (LCx) artery. The LAD supplies blood to the front and sides of the heart, while the LCx supplies blood to the back and sides of the heart. The right coronary artery supplies blood to the lower part of the heart, including the right ventricle and the bottom portion of the left ventricle.

The veins that drain the heart muscle include the great cardiac vein, the middle cardiac vein, and the small cardiac vein, which merge to form the coronary sinus. The coronary sinus empties into the right atrium, allowing deoxygenated blood to enter the right side of the heart and be pumped to the lungs for oxygenation.

Coronary circulation is essential for maintaining the health and function of the heart muscle, as it provides the necessary oxygen and nutrients required for proper contraction and relaxation of the myocardium. Any disruption or blockage in the coronary circulation system can lead to serious consequences, such as angina, heart attack, or even death.

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.

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.

"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.

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.

Ribonucleosides are organic compounds that consist of a nucleoside bound to a ribose sugar. Nucleosides are formed when a nitrogenous base (such as adenine, guanine, uracil, cytosine, or thymine) is attached to a sugar molecule (either ribose or deoxyribose) via a beta-glycosidic bond. In the case of ribonucleosides, the sugar component is D-ribose. Ribonucleosides play important roles in various biological processes, particularly in the storage, transfer, and expression of genetic information within cells. When ribonucleosides are phosphorylated, they become the building blocks of RNA (ribonucleic acid), a crucial biomolecule involved in protein synthesis and other cellular functions. Examples of ribonucleosides include adenosine, guanosine, uridine, cytidine, and inosine.

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.

Adenosylhomocysteinase is an enzyme that plays a crucial role in the methionine cycle, which is a biochemical pathway involved in the synthesis and metabolism of various essential molecules in the body. The formal medical definition of adenosylhomocysteinase is:

"An enzyme that catalyzes the reversible conversion of S-adenosylhomocysteine to homocysteine and adenosine. This reaction is the first step in the recycling of methionine, a sulfur-containing amino acid that is essential for various metabolic processes, including the synthesis of proteins, neurotransmitters, and phospholipids."

In simpler terms, adenosylhomocysteinase helps break down S-adenosylhomocysteine, a byproduct of methylation reactions in the body, into its component parts: homocysteine and adenosine. This breakdown is essential for the proper functioning of the methionine cycle and the maintenance of normal levels of homocysteine, which can be toxic at high concentrations.

Deficiencies or mutations in the adenosylhomocysteinase gene can lead to an accumulation of S-adenosylhomocysteine and homocysteine, which can contribute to various health issues, including neurological disorders, cardiovascular disease, and developmental abnormalities.

Purinergic P2 receptors are a type of cell surface receptor that bind to purine nucleotides and nucleosides, such as ATP (adenosine triphosphate) and ADP (adenosine diphosphate), and mediate various physiological responses. These receptors are divided into two main families: P2X and P2Y.

P2X receptors are ionotropic receptors, meaning they form ion channels that allow the flow of ions across the cell membrane upon activation. There are seven subtypes of P2X receptors (P2X1-7), each with distinct functional and pharmacological properties.

P2Y receptors, on the other hand, are metabotropic receptors, meaning they activate intracellular signaling pathways through G proteins. There are eight subtypes of P2Y receptors (P2Y1, P2Y2, P2Y4, P2Y6, P2Y11, P2Y12, P2Y13, and P2Y14), each with different G protein coupling specificities and downstream signaling pathways.

Purinergic P2 receptors are widely expressed in various tissues, including the nervous system, cardiovascular system, respiratory system, gastrointestinal tract, and immune system. They play important roles in regulating physiological functions such as neurotransmission, vasodilation, platelet aggregation, smooth muscle contraction, and inflammation. Dysregulation of purinergic P2 receptors has been implicated in various pathological conditions, including pain, ischemia, hypertension, atherosclerosis, and cancer.

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.

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.

"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.

Nucleotides are the basic structural units of nucleic acids, such as DNA and RNA. They consist of a nitrogenous base (adenine, guanine, cytosine, thymine or uracil), a pentose sugar (ribose in RNA and deoxyribose in DNA) and one to three phosphate groups. Nucleotides are linked together by phosphodiester bonds between the sugar of one nucleotide and the phosphate group of another, forming long chains known as polynucleotides. The sequence of these nucleotides determines the genetic information carried in DNA and RNA, which is essential for the functioning, reproduction and survival of all living organisms.

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.

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.

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.

Magnesium is an essential mineral that plays a crucial role in various biological processes in the human body. It is the fourth most abundant cation in the body and is involved in over 300 enzymatic reactions, including protein synthesis, muscle and nerve function, blood glucose control, and blood pressure regulation. Magnesium also contributes to the structural development of bones and teeth.

In medical terms, magnesium deficiency can lead to several health issues, such as muscle cramps, weakness, heart arrhythmias, and seizures. On the other hand, excessive magnesium levels can cause symptoms like diarrhea, nausea, and muscle weakness. Magnesium supplements or magnesium-rich foods are often recommended to maintain optimal magnesium levels in the body.

Some common dietary sources of magnesium include leafy green vegetables, nuts, seeds, legumes, whole grains, and dairy products. Magnesium is also available in various forms as a dietary supplement, including magnesium oxide, magnesium citrate, magnesium chloride, and magnesium glycinate.

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.

The extracellular space is the region outside of cells within a tissue or organ, where various biological molecules and ions exist in a fluid medium. This space is filled with extracellular matrix (ECM), which includes proteins like collagen and elastin, glycoproteins, and proteoglycans that provide structural support and biochemical cues to surrounding cells. The ECM also contains various ions, nutrients, waste products, signaling molecules, and growth factors that play crucial roles in cell-cell communication, tissue homeostasis, and regulation of cell behavior. Additionally, the extracellular space includes the interstitial fluid, which is the fluid component of the ECM, and the lymphatic and vascular systems, through which cells exchange nutrients, waste products, and signaling molecules with the rest of the body. Overall, the extracellular space is a complex and dynamic microenvironment that plays essential roles in maintaining tissue structure, function, and homeostasis.

Hyperemia is a medical term that refers to an increased flow or accumulation of blood in certain capillaries or vessels within an organ or tissue, resulting in its redness and warmth. This can occur due to various reasons such as physical exertion, emotional excitement, local injury, or specific medical conditions.

There are two types of hyperemia: active and passive. Active hyperemia is a physiological response where the blood flow increases as a result of the metabolic demands of the organ or tissue. For example, during exercise, muscles require more oxygen and nutrients, leading to an increase in blood flow. Passive hyperemia, on the other hand, occurs when there is a blockage in the venous outflow, causing the blood to accumulate in the affected area. This can result from conditions like thrombosis or vasoconstriction.

It's important to note that while hyperemia itself is not a disease, it can be a symptom of various underlying medical conditions and should be evaluated by a healthcare professional if it persists or is accompanied by other symptoms.

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.

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.

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.

Norbornanes are a class of compounds in organic chemistry that contain a norbornane skeleton, which is a bicyclic structure consisting of two fused cyclohexane rings. One of the rings is saturated, while the other contains a double bond. The name "norbornane" comes from the fact that it is a "nor" (short for "norcarene") derivative of bornane, which has a similar structure but with a methyl group attached to one of the carbon atoms in the saturated ring.

Norbornanes have a variety of applications in organic synthesis and medicinal chemistry. Some derivatives of norbornane have been explored for their potential as drugs, particularly in the areas of central nervous system agents and anti-inflammatory agents. However, there is no specific medical definition associated with "norbornanes" as they are a class of chemical compounds rather than a medical term or condition.

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.

Perfusion, in medical terms, refers to the process of circulating blood through the body's organs and tissues to deliver oxygen and nutrients and remove waste products. It is a measure of the delivery of adequate blood flow to specific areas or tissues in the body. Perfusion can be assessed using various methods, including imaging techniques like computed tomography (CT) scans, magnetic resonance imaging (MRI), and perfusion scintigraphy.

Perfusion is critical for maintaining proper organ function and overall health. When perfusion is impaired or inadequate, it can lead to tissue hypoxia, acidosis, and cell death, which can result in organ dysfunction or failure. Conditions that can affect perfusion include cardiovascular disease, shock, trauma, and certain surgical procedures.

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.

S-Adenosylhomocysteine (SAH) is a metabolic byproduct formed from the demethylation of various compounds or from the breakdown of S-adenosylmethionine (SAM), which is a major methyl group donor in the body. SAH is rapidly hydrolyzed to homocysteine and adenosine by the enzyme S-adenosylhomocysteine hydrolase. Increased levels of SAH can inhibit many methyltransferases, leading to disturbances in cellular metabolism and potential negative health effects.

Purine nucleosides are fundamental components of nucleic acids, which are the genetic materials found in all living organisms. A purine nucleoside is composed of a purine base (either adenine or guanine) linked to a sugar molecule, specifically ribose in the case of purine nucleosides.

The purine base and sugar moiety are joined together through a glycosidic bond at the 1' position of the sugar. These nucleosides play crucial roles in various biological processes, including energy transfer, signal transduction, and as precursors for the biosynthesis of DNA and RNA.

In the human body, purine nucleosides can be derived from the breakdown of endogenous nucleic acids or through the dietary intake of nucleoproteins. They are further metabolized to form uric acid, which is eventually excreted in the urine. Elevated levels of uric acid in the body can lead to the formation of uric acid crystals and contribute to the development of gout or kidney stones.

A radioligand assay is a type of in vitro binding assay used in molecular biology and pharmacology to measure the affinity and quantity of a ligand (such as a drug or hormone) to its specific receptor. In this technique, a small amount of a radioactively labeled ligand, also known as a radioligand, is introduced to a sample containing the receptor of interest. The radioligand binds competitively with other unlabeled ligands present in the sample for the same binding site on the receptor. After allowing sufficient time for binding, the reaction is stopped, and the amount of bound radioligand is measured using a technique such as scintillation counting. The data obtained from this assay can be used to determine the dissociation constant (Kd) and maximum binding capacity (Bmax) of the receptor-ligand interaction, which are important parameters in understanding the pharmacological properties of drugs and other ligands.

Dinucleoside phosphates are the chemical compounds that result from the linkage of two nucleosides through a phosphate group. Nucleosides themselves consist of a sugar molecule (ribose or deoxyribose) and a nitrogenous base (adenine, guanine, cytosine, thymine, or uracil). When two nucleosides are joined together by an ester bond between the phosphate group and the 5'-hydroxyl group of the sugar moiety, they form a dinucleoside phosphate.

These compounds play crucial roles in various biological processes, particularly in the context of DNA and RNA synthesis and repair. For instance, dinucleoside phosphates serve as building blocks for the formation of longer nucleic acid chains during replication and transcription. They are also involved in signaling pathways and energy transfer within cells.

It is worth noting that the term "dinucleotides" is sometimes used interchangeably with dinucleoside phosphates, although technically, dinucleotides refer to compounds formed by joining two nucleotides (nucleosides plus one or more phosphate groups) rather than just two nucleosides.

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.

RNA editing is a process that alters the sequence of a transcribed RNA molecule after it has been synthesized from DNA, but before it is translated into protein. This can result in changes to the amino acid sequence of the resulting protein or to the regulation of gene expression. The most common type of RNA editing in mammals is the hydrolytic deamination of adenosine (A) to inosine (I), catalyzed by a family of enzymes called adenosine deaminases acting on RNA (ADARs). Inosine is recognized as guanosine (G) by the translation machinery, leading to A-to-G changes in the RNA sequence. Other types of RNA editing include cytidine (C) to uridine (U) deamination and insertion/deletion of nucleotides. RNA editing is a crucial mechanism for generating diversity in gene expression and has been implicated in various biological processes, including development, differentiation, and disease.

Equilibrative Nucleoside Transporter 1 (ENT1), also known as SLC29A1, is a protein that functions as a membrane transport protein. It is responsible for the facilitated diffusion of nucleosides and some related drugs across the cell membrane. The term "equilibrative" refers to the fact that this transporter moves substrates down their concentration gradient, meaning it facilitates the movement of molecules from an area of high concentration to an area of low concentration. ENT1 is widely expressed in various tissues, including the liver, kidney, intestine, and brain, playing a crucial role in nucleoside homeostasis and the cellular uptake of nucleoside-analog drugs used in cancer chemotherapy.

Adenosine diphosphate (ADP) sugars, also known as sugar nucleotides, are molecules that play a crucial role in the biosynthesis of complex carbohydrates, such as glycoproteins and glycolipids. These molecules consist of a sugar molecule, usually glucose or galactose, linked to a molecule of adenosine diphosphate (ADP).

The ADP portion of the molecule provides the energy needed for the transfer of the sugar moiety to other molecules during the process of glycosylation. The reaction is catalyzed by enzymes called glycosyltransferases, which transfer the sugar from the ADP-sugar donor to an acceptor molecule, such as a protein or lipid.

ADP-sugars are important in various biological processes, including cell recognition, signal transduction, and protein folding. Abnormalities in the metabolism of ADP-sugars have been implicated in several diseases, including cancer, inflammation, and neurodegenerative disorders.

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.

Purinergic P2 receptor antagonists are pharmaceutical agents that block the activity of P2 receptors, which are a type of cell surface receptor that binds extracellular nucleotides such as ATP and ADP. These receptors play important roles in various physiological processes, including neurotransmission, inflammation, and platelet aggregation.

P2 receptors are divided into two main subfamilies: P2X and P2Y. The P2X receptors are ligand-gated ion channels that allow the flow of ions across the cell membrane upon activation, while the P2Y receptors are G protein-coupled receptors that activate intracellular signaling pathways.

Purinergic P2 receptor antagonists are used in clinical medicine to treat various conditions, such as chronic pain, urinary incontinence, and cardiovascular diseases. For example, the P2X3 receptor antagonist gefapixant is being investigated for the treatment of refractory chronic cough, while the P2Y12 receptor antagonists clopidogrel and ticagrelor are used to prevent thrombosis in patients with acute coronary syndrome.

Overall, purinergic P2 receptor antagonists offer a promising therapeutic approach for various diseases by targeting specific receptors involved in pathological processes.

Guanosine is a nucleoside that consists of a guanine base linked to a ribose sugar molecule through a beta-N9-glycosidic bond. It plays a crucial role in various biological processes, such as serving as a building block for DNA and RNA during replication and transcription. Guanosine triphosphate (GTP) and guanosine diphosphate (GDP) are important energy carriers and signaling molecules involved in intracellular regulation. Additionally, guanosine has been studied for its potential role as a neuroprotective agent and possible contribution to cell-to-cell communication.

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.

"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.

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.

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.

Equilibrative Nucleoside Transporter 2 (ENT2) is a type of protein found in the cell membrane that facilitates the bidirectional transport of nucleosides, which are the building blocks of DNA and RNA, between the intracellular and extracellular spaces. ENT2 is a member of the solute carrier 29 (SLC29) family of transporters and is widely expressed in various tissues, including the brain, liver, kidney, and intestine.

ENT2 plays an essential role in maintaining nucleoside homeostasis by regulating their uptake and efflux across the cell membrane. It has a high affinity for purine nucleosides such as adenosine and guanosine, and to a lesser extent, pyrimidine nucleosides such as uridine and thymidine. The activity of ENT2 is critical in regulating extracellular adenosine levels, which have important implications for various physiological processes, including neurotransmission, inflammation, and cancer.

In addition to its role in nucleoside transport, ENT2 has been implicated in the development of drug resistance in cancer cells. Certain chemotherapeutic agents, such as nucleoside analogs, utilize ENT2 for their uptake into cells. However, overexpression of ENT2 in cancer cells can lead to increased efflux of these drugs, resulting in reduced intracellular concentrations and decreased therapeutic effectiveness. Therefore, ENT2 is an attractive target for the development of novel strategies to overcome drug resistance in cancer therapy.

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.

Phosphotransferases are a group of enzymes that catalyze the transfer of a phosphate group from a donor molecule to an acceptor molecule. This reaction is essential for various cellular processes, including energy metabolism, signal transduction, and biosynthesis.

The systematic name for this group of enzymes is phosphotransferase, which is derived from the general reaction they catalyze: D-donor + A-acceptor = D-donor minus phosphate + A-phosphate. The donor molecule can be a variety of compounds, such as ATP or a phosphorylated protein, while the acceptor molecule is typically a compound that becomes phosphorylated during the reaction.

Phosphotransferases are classified into several subgroups based on the type of donor and acceptor molecules they act upon. For example, kinases are a subgroup of phosphotransferases that transfer a phosphate group from ATP to a protein or other organic compound. Phosphatases, another subgroup, remove phosphate groups from molecules by transferring them to water.

Overall, phosphotransferases play a critical role in regulating many cellular functions and are important targets for drug development in various diseases, including cancer and neurological disorders.

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.

Glyburide is a medication that falls under the class of drugs known as sulfonylureas. It is primarily used to manage type 2 diabetes by lowering blood sugar levels. Glyburide works by stimulating the release of insulin from the pancreas, thereby increasing the amount of insulin available in the body to help glucose enter cells and decrease the level of glucose in the bloodstream.

The medical definition of Glyburide is:
A second-generation sulfonylurea antidiabetic drug (oral hypoglycemic) used in the management of type 2 diabetes mellitus. It acts by stimulating pancreatic beta cells to release insulin and increases peripheral glucose uptake and utilization, thereby reducing blood glucose levels. Glyburide may also decrease glucose production in the liver.

It is important to note that Glyburide should be used as part of a comprehensive diabetes management plan that includes proper diet, exercise, regular monitoring of blood sugar levels, and other necessary lifestyle modifications. As with any medication, it can have side effects and potential interactions with other drugs, so it should only be taken under the supervision of a healthcare provider.

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.

Suramin is a medication that has been used for the treatment of African sleeping sickness, which is caused by trypanosomes. It works as a reverse-specific protein kinase CK inhibitor and also blocks the attachment of the parasite to the host cells. Suramin is not absorbed well from the gastrointestinal tract and is administered intravenously.

It should be noted that Suramin is an experimental treatment for other conditions such as cancer, neurodegenerative diseases, viral infections and autoimmune diseases, but it's still under investigation and has not been approved by FDA for those uses.

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.

Anoxia is a medical condition that refers to the absence or complete lack of oxygen supply in the body or a specific organ, tissue, or cell. This can lead to serious health consequences, including damage or death of cells and tissues, due to the vital role that oxygen plays in supporting cellular metabolism and energy production.

Anoxia can occur due to various reasons, such as respiratory failure, cardiac arrest, severe blood loss, carbon monoxide poisoning, or high altitude exposure. Prolonged anoxia can result in hypoxic-ischemic encephalopathy, a serious condition that can cause brain damage and long-term neurological impairments.

Medical professionals use various diagnostic tests, such as blood gas analysis, pulse oximetry, and electroencephalography (EEG), to assess oxygen levels in the body and diagnose anoxia. Treatment for anoxia typically involves addressing the underlying cause, providing supplemental oxygen, and supporting vital functions, such as breathing and circulation, to prevent further damage.

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.

Formycins are a group of antibiotics that are derived from certain strains of Streptomyces bacteria. They include formycin B (also known as pyrazofurin), which is an antiviral and antimetabolite drug that works by interfering with the production of genetic material in cells. Formycins are not widely used in clinical medicine due to their potential toxicity and the availability of other effective antibiotics and antiviral drugs.

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.

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.

Purine-nucleoside phosphorylase (PNP) is an enzyme that plays a crucial role in the metabolism of purines, which are essential components of nucleic acids (DNA and RNA). The medical definition of 'Purine-Nucleoside Phosphorylase' refers to the physiological function of this enzyme in the human body.

PNP is responsible for catalyzing the phosphorolytic cleavage of purine nucleosides, such as inosine and guanosine, into their respective purine bases (hypoxanthine and guanine) and ribose-1-phosphate. This reaction is essential for the recycling and salvage of purine bases, allowing the body to conserve energy and resources needed for de novo purine biosynthesis.

In a clinical or medical context, deficiencies in PNP activity can lead to serious consequences, particularly affecting the immune system and the nervous system. A genetic disorder called Purine-Nucleoside Phosphorylase Deficiency (PNP Deficiency) is characterized by significantly reduced or absent PNP enzyme activity, leading to an accumulation of toxic purine nucleosides and deoxypurine nucleosides. This accumulation can cause severe combined immunodeficiency (SCID), neurological impairments, and other complications, making it a critical area of study in medical research.

Coronary vessels refer to the network of blood vessels that supply oxygenated blood and nutrients to the heart muscle, also known as the myocardium. The two main coronary arteries are the left main coronary artery and the right coronary artery.

The left main coronary artery branches off into the left anterior descending artery (LAD) and the left circumflex artery (LCx). The LAD supplies blood to the front of the heart, while the LCx supplies blood to the side and back of the heart.

The right coronary artery supplies blood to the right lower part of the heart, including the right atrium and ventricle, as well as the back of the heart.

Coronary vessel disease (CVD) occurs when these vessels become narrowed or blocked due to the buildup of plaque, leading to reduced blood flow to the heart muscle. This can result in chest pain, shortness of breath, or a heart attack.

AMP deaminase is an enzyme that is responsible for the conversion of adenosine monophosphate (AMP) to inosine monophosphate (IMP), which is a part of the purine nucleotide cycle. This enzyme plays a crucial role in energy metabolism, particularly in muscles during exercise. A deficiency in AMP deaminase has been linked to muscle fatigue and weakness.

Potassium channels are membrane proteins that play a crucial role in regulating the electrical excitability of cells, including cardiac, neuronal, and muscle cells. These channels facilitate the selective passage of potassium ions (K+) across the cell membrane, maintaining the resting membrane potential and shaping action potentials. They are composed of four or six subunits that assemble to form a central pore through which potassium ions move down their electrochemical gradient. Potassium channels can be modulated by various factors such as voltage, ligands, mechanical stimuli, or temperature, allowing cells to fine-tune their electrical properties and respond to different physiological demands. Dysfunction of potassium channels has been implicated in several diseases, including cardiac arrhythmias, epilepsy, and neurodegenerative disorders.

"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.

Purinergic P2 receptor agonists are substances that bind and activate purinergic P2 receptors, which are a type of cell surface receptor found in many tissues throughout the body. These receptors are activated by extracellular nucleotides, such as ATP (adenosine triphosphate) and ADP (adenosine diphosphate), and play important roles in various physiological processes, including neurotransmission, muscle contraction, and inflammation.

P2 receptors are divided into two main subfamilies: P2X and P2Y. P2X receptors are ligand-gated ion channels that allow the flow of ions across the cell membrane when activated, while P2Y receptors are G protein-coupled receptors that activate intracellular signaling pathways.

Purinergic P2 receptor agonists can be synthetic or naturally occurring compounds that selectively bind to and activate specific subtypes of P2 receptors. They have potential therapeutic applications in various medical conditions, such as pain management, cardiovascular diseases, and neurological disorders. However, their use must be carefully monitored due to the potential for adverse effects, including desensitization of receptors and activation of unwanted signaling pathways.

Ischemic preconditioning, myocardial is a phenomenon in cardiac physiology where the heart muscle (myocardium) is made more resistant to the damaging effects of a prolonged period of reduced blood flow (ischemia) or oxygen deprivation (hypoxia), followed by reperfusion (restoration of blood flow). This resistance is developed through a series of brief, controlled episodes of ischemia and reperfusion, which act as "preconditioning" stimuli, protecting the myocardium from subsequent more severe ischemic events. The adaptive responses triggered during preconditioning include the activation of various protective signaling pathways, release of protective factors, and modulation of cellular metabolism, ultimately leading to reduced infarct size, improved contractile function, and attenuated reperfusion injury in the myocardium.

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.

Ribose is a simple carbohydrate, specifically a monosaccharide, which means it is a single sugar unit. It is a type of sugar known as a pentose, containing five carbon atoms. Ribose is a vital component of ribonucleic acid (RNA), one of the essential molecules in all living cells, involved in the process of transcribing and translating genetic information from DNA to proteins. The term "ribose" can also refer to any sugar alcohol derived from it, such as D-ribose or Ribitol.

In the context of medical and biological sciences, a "binding site" refers to a specific location on a protein, molecule, or cell where another molecule can attach or bind. This binding interaction can lead to various functional changes in the original protein or molecule. The other molecule that binds to the binding site is often referred to as a ligand, which can be a small molecule, ion, or even another protein.

The binding between a ligand and its target binding site can be specific and selective, meaning that only certain ligands can bind to particular binding sites with high affinity. This specificity plays a crucial role in various biological processes, such as signal transduction, enzyme catalysis, or drug action.

In the case of drug development, understanding the location and properties of binding sites on target proteins is essential for designing drugs that can selectively bind to these sites and modulate protein function. This knowledge can help create more effective and safer therapeutic options for various diseases.

Dilazep is a medication that belongs to a class of drugs called calcium channel blockers. It is primarily used in the management of angina pectoris, which is chest pain caused by reduced blood flow to the heart muscle. Dilazep works by relaxing and widening the blood vessels that supply the heart, thereby improving blood flow and reducing the workload on the heart.

The chemical name for Dilazep is (E)-1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridinedicarboxylic acid diamide. It is not commonly used in many countries, and other calcium channel blockers such as verapamil, nifedipine, and amlodipine are more frequently prescribed for the treatment of angina pectoris.

It's important to note that like all medications, Dilazep can have side effects, including headache, dizziness, and swelling in the extremities. It should be used under the close supervision of a healthcare provider, who can monitor its effectiveness and potential side effects.

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.

Uridine Triphosphate (UTP) is a nucleotide that plays a crucial role in the synthesis and repair of DNA and RNA. It consists of a nitrogenous base called uracil, a pentose sugar (ribose), and three phosphate groups. UTP is one of the four triphosphates used in the biosynthesis of RNA during transcription, where it donates its uracil base to the growing RNA chain. Additionally, UTP serves as an energy source and a substrate in various biochemical reactions within the cell, including phosphorylation processes and the synthesis of glycogen and other molecules.

Affinity labels are chemical probes or reagents that can selectively and covalently bind to a specific protein or biomolecule based on its biological function or activity. These labels contain a functional group that interacts with the target molecule, often through non-covalent interactions such as hydrogen bonding, van der Waals forces, or ionic bonds. Once bound, the label then forms a covalent bond with the target molecule, allowing for its isolation and further study.

Affinity labels are commonly used in biochemistry and molecular biology research to identify and characterize specific proteins, enzymes, or receptors. They can be designed to bind to specific active sites, binding pockets, or other functional regions of a protein, allowing researchers to study the structure-function relationships of these molecules.

One example of an affinity label is a substrate analogue that contains a chemically reactive group. This type of affinity label can be used to identify and characterize enzymes by binding to their active sites and forming a covalent bond with the enzyme. The labeled enzyme can then be purified and analyzed to determine its structure, function, and mechanism of action.

Overall, affinity labels are valuable tools for studying the properties and functions of biological molecules in vitro and in vivo.

C57BL/6 (C57 Black 6) is an inbred strain of laboratory mouse that is widely used in biomedical research. The term "inbred" refers to a strain of animals where matings have been carried out between siblings or other closely related individuals for many generations, resulting in a population that is highly homozygous at most genetic loci.

The C57BL/6 strain was established in 1920 by crossing a female mouse from the dilute brown (DBA) strain with a male mouse from the black strain. The resulting offspring were then interbred for many generations to create the inbred C57BL/6 strain.

C57BL/6 mice are known for their robust health, longevity, and ease of handling, making them a popular choice for researchers. They have been used in a wide range of biomedical research areas, including studies of cancer, immunology, neuroscience, cardiovascular disease, and metabolism.

One of the most notable features of the C57BL/6 strain is its sensitivity to certain genetic modifications, such as the introduction of mutations that lead to obesity or impaired glucose tolerance. This has made it a valuable tool for studying the genetic basis of complex diseases and traits.

Overall, the C57BL/6 inbred mouse strain is an important model organism in biomedical research, providing a valuable resource for understanding the genetic and molecular mechanisms underlying human health and disease.

Dideoxyadenosine (ddA) is a type of synthetic nucleoside analogue, which is a synthetic compound that resembles one of the building blocks of DNA or RNA. More specifically, ddA resembles adenosine, one of the four nucleosides that make up DNA.

Dideoxyadenosine is used in research and medicine as an inhibitor of reverse transcriptase, an enzyme that is produced by retroviruses such as HIV. By blocking the action of this enzyme, ddA can prevent the virus from replicating and infecting new cells.

Dideoxyadenosine is often used in combination with other antiretroviral drugs as part of highly active antiretroviral therapy (HAART) to treat HIV infection and AIDS. It is usually administered as a prodrug, such as didanosine or ddI, which is converted to the active form of the drug in the body.

It's important to note that Dideoxyadenosine itself is not used directly as a medication but its derivatives like Didanosine are used in treatment.

Isopentenyladenosine (IPA) is a derivative of adenosine, which is a nucleoside consisting of adenine attached to ribose sugar via a β-N9-glycosidic bond. In Isopentenyladenosine, an isopentenyl group (a hydrocarbon chain with five carbon atoms) is added to the N6 position of the adenine base.

Isopentenyladenosine is a key intermediate in the biosynthesis of cytokinins, a class of plant hormones that play crucial roles in cell division and differentiation, shoot initiation, leaf expansion, apical dominance, root growth, and other developmental processes.

It's worth noting that Isopentenyladenosine is not typically used as a medical term or definition but rather in the context of biochemistry and plant physiology.

I couldn't find a medical definition for "Depression, Chemical" as it is not a recognized medical term. However, I can provide you with information about chemical imbalances in the brain that are associated with depression.

Major depressive disorder (MDD), commonly referred to as depression, is believed to be caused by a combination of genetic, environmental, and physiological factors. While there is no definitive evidence that depression is solely caused by a "chemical imbalance," neurotransmitter irregularities in the brain are associated with depressive symptoms. Neurotransmitters are chemical messengers that transmit signals in the brain and other parts of the body. Some of the primary neurotransmitters involved in mood regulation include serotonin, norepinephrine, and dopamine.

In depression, it is thought that there may be alterations in the functioning of these neurotransmitter systems, leading to an imbalance. For example:

1. Serotonin: Low levels of serotonin are associated with depressive symptoms. Selective serotonin reuptake inhibitors (SSRIs), a common class of antidepressants, work by increasing the availability of serotonin in the synapse (the space between neurons) to improve communication between brain cells.
2. Norepinephrine: Imbalances in norepinephrine levels can contribute to depressive symptoms and anxiety. Norepinephrine reuptake inhibitors (NRIs), tricyclic antidepressants (TCAs), and monoamine oxidase inhibitors (MAOIs) are medications that target norepinephrine to help alleviate depression.
3. Dopamine: Deficiencies in dopamine can lead to depressive symptoms, anhedonia (the inability to feel pleasure), and motivation loss. Some antidepressants, like bupropion, work by increasing dopamine levels in the brain.

In summary, while "Chemical Depression" is not a recognized medical term, chemical imbalances in neurotransmitter systems are associated with depressive symptoms. However, depression is a complex disorder that cannot be solely attributed to a single cause or a simple chemical imbalance. It is essential to consider multiple factors when diagnosing and treating depression.

The adenosine A1 receptor is one member of the adenosine receptor group of G protein-coupled receptors with adenosine as ... The adenosine A1 receptor has been found to be ubiquitous throughout the entire body. Activation of the adenosine A1 receptor ... "Adenosine Receptors: A1". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology ... Adenosine+A1+Receptor at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Human ADORA1 genome location and ...
"Chromosomal mapping of A1 and A2 adenosine receptors, VIP receptor, and a new subtype of serotonin receptor". Genomics. 11 (1 ... As a result, Adenosine receptor A2A decreases activity in the Dopamine D2 receptors. The adenosine A2A receptor has also been ... "Chromosomal mapping of A1 and A2 adenosine receptors, VIP receptor, and a new subtype of serotonin receptor". Genomics. 11 (1 ... The adenosine A2A receptor, also known as ADORA2A, is an adenosine receptor, and also denotes the human gene encoding it. This ...
All adenosine receptor subtypes (A1, A2A, A2B, and A3) are G-protein-coupled receptors. The four receptor subtypes are further ... The A1 receptors couple to Gi/o and decrease cAMP levels, while the A2 adenosine receptors couple to Gs, which stimulates ... Cellular signaling by adenosine occurs through four known adenosine receptor subtypes (A1, A2A, A2B, and A3). Extracellular ... Caffeine acts by blocking binding of adenosine to the adenosine A1 receptor, which enhances release of the neurotransmitter ...
The adenosine A1 receptor has been found to be ubiquitous throughout the entire body. This receptor has an inhibitory function ... The adenosine receptors (or P1 receptors) are a class of purinergic G protein-coupled receptors with adenosine as the ... Adenosine receptors play a key role in the homeostasis of bone. The A1 receptor has been shown to stimulate osteoclast ... Each type of adenosine receptor has different functions, although with some overlap. For instance, both A1 receptors and A2A ...
Adenosine A1-A2A receptor heteromers: new targets for caffeine in the brain. Frontiers in Bioscience. Volume 13. Pages 2391- ... Adenosine A2A receptor antagonists are a class of drugs that blocks adenosine at the adenosine A2A receptor. Notable adenosine ... adenosine receptor antagonists as potential therapeutics, antagonist for A2A-receptors, adenosine receptor ligands as anti- ... A2A receptors are G-protein coupled receptor (GPCR) that increases cyclic adenosine monophosphate (cAMP). These receptors are ...
It is also an adenosine receptor A1 antagonist. 8-Chlorotheophylline 8-Cyclopentyltheophylline 8-Phenyltheophylline Ortiz MI, ... September 1993). "Effect of trifluoromethyl and other substituents on activity of xanthines at adenosine receptors". Journal of ... Adenosine receptor antagonists, Xanthines, Diuretics, All stub articles, Nervous system drug stubs). ...
"Cardiac myocytes rendered ischemia resistant by expressing the human adenosine A1 or A3 receptor". FASEB Journal. 12 (15): 1785 ... is an adenosine receptor, but also denotes the human gene encoding it. Adenosine A3 receptors are G protein-coupled receptors ... January 2013). "Interaction of SSR161421, a novel specific adenosine A(3) receptor antagonist with adenosine A(3) receptor ... a novel ligand that demonstrates both adenosine A(2A) receptor agonist and adenosine A(3) receptor antagonist activity". ...
... modified adenosine derivatives as high-affinity and selective agonists at the human A1 adenosine receptor with antinociceptive ... "N6-Cycloalkyl-2-substituted adenosine derivatives as selective, high affinity adenosine A1 receptor agonists". Bioorganic & ... N6-Cyclopentyladenosine (CPA) is a drug which acts as a selective adenosine A1 receptor agonist. It has mainly cardiovascular ... Elzein E, Zablocki J (December 2008). "A1 adenosine receptor agonists and their potential therapeutic applications". Expert ...
Bauman LA, Mahle CD, Boissard CG, Gribkoff VK (1992). "Age-dependence of effects of A1 adenosine receptor antagonism in rat ... Chaudary N, Naydenova Z, Shuralyova I, Coe IR (2004). "The adenosine transporter, mENT1, is a target for adenosine receptor ... "Adenosine and adenosine uptake inhibitors potentiate the neuromuscular blocking action of rocuronium mediated by adenosine A(1 ... York MJ, Davies LP (1982). "The effect of diazepam on adenosine uptake and adenosine-stimulated adenylate cyclase in guinea-pig ...
Schwabe U, Ukena D, Lohse MJ (September 1985). "Xanthine derivatives as antagonists at A1 and A2 adenosine receptors". Naunyn- ... It acts as an adenosine receptor antagonist and phosphodiesterase inhibitor. Xanthine "International Non-Proprietary Names. ... Adenosine receptor antagonists, Diols, Phosphodiesterase inhibitors, Xanthines, All stub articles, Respiratory system drug ...
Björklund O, Shang M, Tonazzini I, Daré E, Fredholm BB (2008). "Adenosine A1 and A3 receptors protect astrocytes from hypoxic ... eCollection 2015 Gessi S, Merighi S, Stefanelli A, Fazzi D, Varani K, Borea PA (2013). "A(1) and A(3) adenosine receptors ... Memory has been associated with astrocytes and the alpha3 subunit of adenosine receptor found in hydrogen/Sodium-potassium ... H2-receptor antagonists, like cimetidine (Tagamet), inhibit the signaling pathway that leads to activation of the ATPase. This ...
... excess free adenosine down-regulates primary A1 adenosine receptors, leading to increased muscle pain. Secondary receptors (A3 ... Adenosine mediates pain through adenosine receptors. MADD causes an increase of free adenosine during heavy activity which may ... In the brain, excess adenosine decreases alertness and causes sleepiness. In this way, adenosine may play a role in fatigue ... Adenosine monophosphate deaminase deficiency type 1 or AMPD1, is a human metabolic disorder in which the body consistently ...
... caffeine blocks adenosine receptors A1 and A2A. Adenosine is a by-product of cellular activity, the stimulation of adenosine ... Caffeine dependence forms due to caffeine antagonizing the adenosine A2A receptor, effectively blocking adenosine from the ... Continued exposure to caffeine leads the body to create more adenosine-receptors in the central nervous system, which makes it ... adenosine receptor site. This delays the onset of drowsiness and releases dopamine. As of right now, caffeine withdrawal ...
October 2001). "Differential gene expression of adenosine A1, A2a, A2b, and A3 receptors in the human enteric nervous system". ... The adenosine A2B receptor, also known as ADORA2B, is a G-protein coupled adenosine receptor, and also denotes the human ... "The A2b adenosine receptor mediates cAMP responses to adenosine receptor agonists in human intestinal epithelia". The Journal ... "Adenosine Receptors: A2B". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical ...
"Hypoxia induces cardiac malformations via A1 adenosine receptor activation in chicken embryos". Birth Defects Research. Part A ... "Haploinsufficiency of the NOTCH1 Receptor as a Cause of Adams-Oliver Syndrome With Variable Cardiac Anomalies". Circulation: ...
... is a drug which acts as a potent and selective antagonist for the adenosine A1 receptor. It has high selectivity for A1 over ... "Potent adenosine receptor antagonists that are selective for the A1 receptor subtype". Molecular Pharmacology. 31 (3): 247-52. ... It has been used to study the function of the adenosine A1 receptor in animals, which has been found to be involved in several ... De Sarro G, Donato Di Paola E, Falconi U, Ferreri G, De Sarro A (December 1996). "Repeated treatment with adenosine A1 receptor ...
... activity as antagonists of A1- and A2-adenosine receptors". Biochemical Pharmacology. 37 (4): 655-64. doi:10.1016/0006-2952(88) ... Adenosine receptor antagonists, Amines, Ethyl esters, Carboxylate esters, GABAA receptor positive allosteric modulators, ... It is also known to act as an adenosine antagonist at the A1 and A2 subtypes and as a phosphodiesterase inhibitor. Cartazolate ... "Perturbation of benzodiazepine receptor binding by pyrazolopyridines involves picrotoxinin/barbiturate receptor sites". Journal ...
... inhibits the A1 adenosine receptor and functionally blocks Gi, an inhibitory regulator. Sulmazole is also a ... Parsons WJ, Ramkumar V, Stiles GL (April 1988). "The new cardiotonic agent sulmazole is an A1 adenosine receptor antagonist and ...
Adenosine modulates the preBötC output via activation of the A1 and A2A receptor subtypes. An adenosine A1 receptor agonist has ... Another synthetic drug specific to the adenosine A2A receptor subtype is CGS-21680 that has been shown to cause apneas in 14- ... Since many of these neurons express GABA, glutamate, serotonin and adenosine receptors, chemicals custom tailored to bind at ... Mayer CA, Haxhiu MA, Martin RJ, Wilson CG (January 2006). "Adenosine A2A receptors mediate GABAergic inhibition of respiration ...
The anti-nociceptive effect of acupuncture may be mediated by the adenosine A1 receptor. A 2014 review in Nature Reviews Cancer ... which then triggered nearby A1 receptors. The review found that in those studies, because acupuncture "caused more tissue ... Mechanical deformation of the skin by acupuncture needles appears to result in the release of adenosine. ... such studies unnecessarily muddled a finding that local inflammation can result in the local release of adenosine with ...
... is a drug of the xanthine chemical class which acts as a selective adenosine A1 receptor antagonist. Theophylline ... "Effects of A1 adenosine receptor blockade by bamiphylline on ischaemic preconditioning during coronary angioplasty". European ... Adenosine receptor antagonists, Enones, Primary alcohols, Xanthines, All stub articles, Respiratory system drug stubs, ...
Adenosine constricts the afferent arteriole by binding with high affinity to the A1 receptors a Gi/Go. Adenosine binds with ... "In part because of the striking effect of deletion of A1 adenosine receptors (A1AR), adenosine generated from released ATP has ... Vallon V, Osswald H (2009). "Adenosine receptors and the kidney". Adenosine Receptors in Health and Disease. Handbook of ... The binding of adenosine to the A1 receptor causes a complex signal cascade involving the Gi subunit deactivating Ac, thus ...
2-Chloro-N6-cyclopentyladenosine (CCPA) is a specific receptor agonist for the Adenosine A1 receptor. It is similar to N6- ... Due to CCPA's high affinity for Adenosine A1 receptors, its tritiated derivative [3H]CCPA can be used as a diagnostic tool for ... a high affinity agonist radioligand for A1 adenosine receptors". Naunyn-Schmiedeberg's Archives of Pharmacology. 340: 679-683. ... a high affinity agonist radioligand for A1 adenosine receptors". Naunyn-Schmiedeberg's Archives of Pharmacology. 340 (6): 679- ...
ATL146e (A2A selective) PD81,723 (A1 allosteric enhancer) CF102 (Adenosine A3 receptor) Adenosine receptor antagonist Adenosine ... An adenosine receptor agonist is a drug which acts as an agonist of one or more of the adenosine receptors. Examples include ... the neurotransmitter adenosine, its phosphates, adenosine monophosphate (AMP), adenosine diphosphate (ADP), and adenosine ... v t e (Drugs acting on the nervous system, Adenosine receptor agonists, All stub articles, Nervous system drug stubs). ...
Givertz MM, Massie BM, Fields TK, Pearson LL, Dittrich HC (October 2007). "The effects of KW-3902, an adenosine A1-receptor ... Rolofylline (KW-3902) is an experimental diuretic which acts as a selective adenosine A1 receptor antagonist. It was discovered ... dose-finding study of the adenosine A1 receptor antagonist rolofylline in patients with acute heart failure and renal ... Adenosine receptor antagonists, Diuretics, Xanthines, All stub articles, Cardiovascular system drug stubs). ...
... these neurons express D1-type dopamine receptors, adenosine A1 receptors, dynorphin peptides, and substance P peptides. ... Both types express glutamate receptors (NMDAR and AMPAR), cholinergic receptors (M1 and M4) and CB1 receptors are expressed on ... they also express adenosine A1 receptors), while dynorphinergic MSNs connect the striatum with the substantia nigra (pars ... and express the peptides dynorphin and substance P and dopamine D1 and adenosine A1 but not A2A receptors (Ferréet al., 1997; ...
Popoli P, Reggio R, Pèzzola A, Fuxe K, Ferré S (July 1998). "Adenosine A1 and A2A receptor antagonists stimulate motor activity ... Kuzmin A, Johansson B, Gimenez L, Ogren SO, Fredholm BB (February 2006). "Combination of adenosine A1 and A2A receptor blocking ... SCH-58261 is a drug which acts as a potent and selective antagonist for the adenosine receptor A2A, with more than 50x ... Minghetti L, Greco A, Potenza RL, Pezzola A, Blum D, Bantubungi K, Popoli P (May 2007). "Effects of the adenosine A2A receptor ...
Dhalla AK, Shryock JC, Shreeniwas R, Belardinelli L (2003). "Pharmacology and therapeutic applications of A1 adenosine receptor ... adenosine receptor antagonist, on the negative inotropic action of A(1) adenosine receptor full agonists in isolated guinea pig ... Hormone receptors Neuromodulator receptors Neurotransmitter receptors General anesthetics were once thought to work by ... More precisely, receptor reserve refers to a phenomenon whereby stimulation of only a fraction of the whole receptor population ...
"Control of Cannabinoid CB1 Receptor Function on Glutamate Axon Terminals by Endogenous Adenosine Acting at A1 Receptors". ... "Regulation of Hippocampal Cannabinoid CB1 Receptor Actions by Adenosine A1 Receptors and Chronic Caffeine Administration: ... v t e v t e (CS1: long volume value, Receptors, Cell signaling, All stub articles, Receptor stubs, Molecular and cellular ... A heteroreceptor is a receptor regulating the synthesis and/or the release of mediators other than its own ligand. ...
"Chromosomal mapping of A1 and A2 adenosine receptors, VIP receptor, and a new subtype of serotonin receptor". Genomics. 11 (1 ... Atypical chemokine receptor 3 also known as C-X-C chemokine receptor type 7 (CXCR-7) and G-protein coupled receptor 159 (GPR159 ... This gene encodes a G protein-coupled receptor family member. It belongs to the chemokine receptor family of GPCRs. Within this ... and was considered to be an orphan receptor. It is now classified as a chemokine receptor able to bind the chemokines CXCL12/ ...
The adenosine A1 receptor is one member of the adenosine receptor group of G protein-coupled receptors with adenosine as ... The adenosine A1 receptor has been found to be ubiquitous throughout the entire body. Activation of the adenosine A1 receptor ... "Adenosine Receptors: A1". IUPHAR Database of Receptors and Ion Channels. International Union of Basic and Clinical Pharmacology ... Adenosine+A1+Receptor at the U.S. National Library of Medicine Medical Subject Headings (MeSH) Human ADORA1 genome location and ...
Ratio of binding affinities for adenosine receptor A2a and adenosine receptor A1. ...
Persistent Activation by and Receptor Reserve for an Irreversible A1-Adenosine Receptor Agonist in DDT1 MF-2 Cells and in ... Persistent Activation by and Receptor Reserve for an Irreversible A1-Adenosine Receptor Agonist in DDT1 MF-2 Cells and in ... Persistent Activation by and Receptor Reserve for an Irreversible A1-Adenosine Receptor Agonist in DDT1 MF-2 Cells and in ... Persistent Activation by and Receptor Reserve for an Irreversible A1-Adenosine Receptor Agonist in DDT1 MF-2 Cells and in ...
A1 adenosine receptor, A2 adenosine receptor, vascular endothelium, vascular smooth muscle, indomethacin, free radicals. ... Evidence for the presence of A1 adenosine receptors in the aorta of spontaneously hypertensive rats. ECU Author/Contributor ( ... The contractile response in SHR was abolished by A1 adenosine receptor antagonist N6- endonorbornan-2-yl-9-methyladenine (N- ... did not a ect the contraction response of adenosine analogues. 7 Endothelium-dependent contractions elicited by A1 receptor ...
To this end, respiration of unrestrained adult and neonatal adenosine A1 receptor knockout mice (A(1)R(-/-)) was measured in a ... To this end, respiration of unrestrained adult and neonatal adenosine A1 receptor knockout mice (A(1)R(-/-)) was measured in a ... The in vivo respiratory phenotype of the adenosine A1 receptor knockout mouse ... In this study the role of adenosine A(1) receptors for the control of respiration was investigated in vivo. ...
Categorized as Adenosine A1 Receptors A novel procedure for in vivo imaging from the air partial. A novel procedure for in vivo ... Categorized as Adenosine A1 Receptors Tagged CH5424802 distributor, FZD10. The efficacy of the ((and in meat at 4oC applying ... Categorized as Adenosine A1 Receptors Tagged Etomoxir tyrosianse inhibitor, Rtn4r. In this research, carrot pulp was put into ... Categorized as Adenosine A1 Receptors Tagged Adrucil inhibitor, Itga10. Interleukin-12 (IL12) is usually a cytokine that is ...
Fax 0032 16 50 90 45. This email address is being protected from spambots. You need JavaScript enabled to view it.. ...
Dopamine release in nucleus accumbens is under tonic inhibition by adenosine A1 receptors regulated by astrocytic ENT1 and ... Dopamine release in nucleus accumbens is under tonic inhibition by adenosine A1 receptors regulated by astrocytic ENT1 and ...
Adenosine A1 receptors mediate local antinociceptive effects of acupuncture. Nat Neurosci. 2010;13:883-889. ... Ankle Joint Mobilization Affects Postoperative Pain Through Peripheral and Central Adenosine A1 Receptors ... Ankle Joint Mobilization Affects Postoperative Pain Through Peripheral and Central Adenosine A1 Receptors. Daniel F. Martins, ... Ankle Joint Mobilization Affects Postoperative Pain Through Peripheral and Central Adenosine A1 Receptors ...
Development of an Adenosine A1 Receptor agonist, MRS5474 for the treatment of chronic depression Project Summary Depression is ... Development of an adenosine A1 receptors agonist, MRS5474 for the treatment of chronic depression Padia, Janak K. Primetime ... Adenosine A1 receptors (A1R) play a key role in neuroprotection and enhanced AA1R function has shown antidepressant effects in ... Development of an adenosine A1 receptors agonist, MRS5474 for the treatment of chronic depression. Padia, Janak K. / Primetime ...
In the basal forebrain, adenosine accumulates during wakefulness and, when locally applied, suppresses neuronal activity and ... Adenosine has been proposed as a homeostatic sleep factor that promotes the transition from waking to sleep by affecting ... Application of the A1 receptor antagonist 8-cyclo-pentyl-theophylline (200 nM) blocked the effects of adenosine. Adenosine was ... In the first group adenosine, via activation of postsynaptic A1 receptors, reduced spontaneous firing via inhibition of the ...
Adenosine A1 Receptor Antagonist Up-regulates Casp3 and Stimulates Apoptosis Rate in Breast Cancer Cell Line T47D Background: ... Background: Adenosine receptor family, especially A1 type is-overexpressed in breast-derived tumor cells and the P53 gene is ... Therefore, adenosine A1 receptor antagonists may be introduced as anti-cancer agents.. ... Investigation the Effect of Adenosine A1 Receptor Agonist and Antagonist on P53 Gene Expression, and Apoptosis Pathways and ...
title = "Adenosine A1 receptors (A1Rs) play a critical role in osteoclast formation and function", ... T1 - Adenosine A1 receptors (A1Rs) play a critical role in osteoclast formation and function ... Adenosine A1 receptors (A1Rs) play a critical role in osteoclast formation and function. / Kara, Firas M.; Chitu, Violeta; ... Adenosine A1 receptors (A1Rs) play a critical role in osteoclast formation and function. In: FASEB Journal. 2010 ; Vol. 24, No ...
Was Adenosine A1 receptor (A1R) Agonist Compound solely attributed to alterations in the alkaline phosphatase activity ... Was Adenosine A1 receptor (A1R) Agonist Compound solely attributed to alterations in the alkaline phosphatase By inhibitor ... Was Adenosine A1 receptor (A1R) Agonist Compound solely attributed to alterations in the alkaline phosphatase activity between ... Was Adenosine A1 receptor (A1R) Agonist Compound solely attributed to alterations in the alkaline phosphatase ...
Antagonists for adenosine A1 receptor and purinergic P2Y1 receptor. COA-Cl (2Cl-C. Antagonists for adenosine A1 receptor and ... Outcomes COA-Cl is a book nucleic acidity analog that resembles adenosine ( Fig structurally. 1A; Mw = 283.71). We initial ... Degrees of the non-target S1P receptor subtype continued to be unchanged in both circumstances (S1P3: 121.8% ± 11.4% in S1P1 ... purinergic P2Y1 receptor had been without effect. Hereditary knockdown of S1P1 with siRNA however not that of S1P3 attenuated ...
Safety and efficacy of the partial adenosine A1 receptor agonist neladenoson bialanate in patients with chronic heart failure ... 2019). Safety and efficacy of the partial adenosine A1 receptor agonist neladenoson bialanate in patients with chronic heart ... 2019). Safety and efficacy of the partial adenosine A1 receptor agonist neladenoson bialanate in patients with chronic heart ... Aims: Neladenoson bialanate is a partial adenosine A1 receptor agonist with demonstrated beneficial effects on cardiac function ...
A1 adenosine receptor antagonist) or TG2 inhibitors (Z-DON and R283) attenuated the A1 adenosine receptor-induced ... The primary aim of this study was to determine the role of TG2 in A1 adenosine receptor and β2-adrenoceptor-induced ... N6-cyclopentyladenosine (CPA; A1 adenosine receptor agonist), formoterol (β2-adrenoceptor agonist) or isoprenaline (non- ... We have previously reported that transglutaminase 2 (TG2) activity is modulated by the A1 adenosine receptor and β2- ...
... utilization during glucose absorption would increase adenosine metabolite release, which acts on adenosine A1 receptors to ... utilization during glucose absorption would increase adenosine metabolite release, which acts on adenosine A1 receptors to ... utilization during glucose absorption would increase adenosine metabolite release, which acts on adenosine A1 receptors to ... utilization during glucose absorption would increase adenosine metabolite release, which acts on adenosine A1 receptors to ...
Adenosine A1 Receptor, Rat. 3,254. 205. 59. 36. Clustered By Gene (4). Code. Description. Substances. Purchasable. Natural. In ... Adenosine A1 Receptor, Mouse. 25. 3. 1. 2. AA1R_RAT. P25099. CHEMBL318. ... Adenosine A1 Receptor, Human. 2,632. 98. 19. 17. AA1R_MOUSE. Q60612. CHEMBL3688. ... Adenosine A1 Receptor, Chick. 24. 3. 0. 1. AA1R_HUMAN. P30542. CHEMBL226. ...
A1 ADENOSINE RECEPTOR REGULATES ATP-MEDIATED MICROGLIAL ACTIVATION IN VIVO AND IN VITRO: ROLE IN THE SPINAL NEURONAL PLASTICITY ... receptors for adenosine and ATP/ADP, respectively. The P2X4 and P2X7 receptors are involved in microglia chemotaxis and ... receptors for adenosine and ATP/ADP, respectively. The P2X4 and P2X7 receptors are involved in microglia chemotaxis and ... Recently, it has been demonstrated that also adenosine A2A receptors (A2AARs) are over-expressed in LPS-activated microglia and ...
In contrast, mNT5E had no antinociceptive effects when injected intrathecally into adenosine A1 receptor (A 1 R, Adora1) ... to adenosine in nociceptive circuits. Since adenosine has antinociceptive effects in rodents and humans, we hypothesized that ... Recombinant mNT5E hydrolyzed AMP in biochemical assays and was inhibited by α,β-methylene-adenosine 5-diphosphate (α,β-me-ADP ... NT5E, an enzyme that generates adenosine, might also have antinociceptive effects in vivo. To test this hypothesis, we purified ...
... adenosine strengthened weight dependence of heterosynaptic plasticity; blockade of adenosine A1 receptors abolished it. In ... 2009) Control and function of the homeostatic sleep response by adenosine A1 receptors. J Neurosci 29:1267-1276. doi:10.1523/ ... 2013) Adenosine A1 receptor activation mediates the developmental shift at layer 5 pyramidal cell synapses and is a determinant ... 1995) Stimulation of A1 adenosine receptors mimics the electroencephalographic effects of sleep deprivation. Brain Res 692:79- ...
Regulation of ethanol-sensitive EAAT2 expression through adenosine A1 receptor in astrocytes. Biochem Biophys Res Commun. 2011; ... which is extracellularly converted to adenosine [62, 63]) or adenosine that activates presynaptic type 1 adenosine receptors [ ... requires localized extracellular catabolism by ecto-nucleotidases into adenosine and channeling to adenosine A1 receptors. J ... Astrocytes express dopamine receptors. A key component of dopaminergic signaling is the activation of dopamine receptors and ...
Rolofylline, an adenosine A1-receptor antagonist, in acute heart failure. N Engl J Med. 2010 Oct 7. 363(15):1419-28. [QxMD ... Angiotensin Receptor-Neprilysin Inhibitors (ARNi) Class Summary. Angiotensin receptor-neprilysin inhibitor (ARNI) combinations ... Norepinephrine is a naturally occurring catecholamine with potent alpha-receptor and mild beta-receptor activity. It stimulates ... Binding to the receptor causes an increase in cGMP, which serves as a second messenger to dilate veins and arteries. It reduces ...
adenosine A1 receptor. ISO. RGD. PMID:18787037. RGD:5129100. NCBI chrNW_004955406:39,148,811...39,183,577 Ensembl chrNW_ ... adenosine A2a receptor. ISO. CTD Direct Evidence: marker/mechanism. CTD. PMID:20532872. NCBI chrNW_004955455:7,886,720... ... TNF receptor superfamily member 1A. ISO. protein:increased expression:serum (human). RGD. PMID:19148690. RGD:5131433. NCBI ... cysteinyl leukotriene receptor 1. ISO. protein:increased expression:tonsil, T cell. RGD. PMID:18490405. RGD:4888517. NCBI chrNW ...
"Selective Activation of Inhibitory-Class Gα Subtypes Confers Unique Pharmacological Effects at Adenosine A1 Receptors". Grant ... M4 muscarinic receptor modulation of striatal biology and repetitive behaviors. Daniel J. Foster, Ph.D. - Faculty Candidate, ... Ph.D. Thesis Proposal: "Role of Orphan G Protein-coupled Receptor GPRC5B in Retinoic Acid-induced Depressive-like Behaviors". ... First-Year Rotation Talks: "Chimeric Antigen Receptors (CARs)". Fatemeh Alimohammadi - Graduate Student in the Laboratory of ...
... adenosine receptor antagonists may be useful in either treating cocaine use or improving disrupted cognitive-behavior.. ... 2008) Adenosine A1-A2A receptor heteromers: new targets for caffeine in the brain. Front Biosci 13: 2391-2399. ... Adenosine A2A receptors form functional heteromers with dopamine D2 receptors located in the striatum, altering the binding and ... 2011) Adenosine A(2A) Receptors and A(2A) Receptor Heteromers as Key Players in Striatal Function. Front Neuroanat 5: 36. ...
... adenosine A-1; ([3H]2-chloroadenosine (2-CADO; 1.0 nM; whole brain crude synaptic membranes; Williams & Risley 1980). ... Examination of cyproheptadine in radioligand receptor-binding assays shoed that it was some five orders of magnitude more ... Radioligand binding to central receptors was measured using membranes prepared from rat brain by described methods as follows ( ... Examination of cyproheptadine in eleven receptor binding assays (Table 1) confirmed the ...
TargetAdenosine receptor A1(Rattus norvegicus (rat)). National Institute of Diabetes, Digestive and Kidney Diseases. Curated by ... TargetAdenosine receptor A2a(Rattus norvegicus (rat)). National Institute of Diabetes, Digestive and Kidney Diseases. Curated ...
... were transferred onto other adjacent slices that had been labelled by receptor autoradiography with the A1 Adenosine receptor ( ... In F98 animals, a significant increase in A1AR receptor protein was found in the Peritumoural zone as a function of time of ... Hence, a method is described for quantifying various receptor protein systems in the tumour as well as in the marginal invasive ... Brains were cryosliced and radio-labelled with a ligand of the peripheral type benzodiazepine-receptor (pBR), 3H-Pk11195 [(1-(2 ...
  • The contractile response in SHR was abolished by A1 adenosine receptor antagonist N6- endonorbornan-2-yl-9-methyladenine (N-0861). (uncg.edu)
  • A2 adenosine receptor antagonist 3 7-dimethyl-1-proparglyxanthine (DMPX) did not a ect the contraction response of adenosine analogues. (uncg.edu)
  • or 150 nmol/paw, i.pl.) antagonist injected before 9 minutes of AJM or adenosine (30 mg/kg, i.p.) treatment. (highwire.org)
  • Application of the A1 receptor antagonist 8-cyclo-pentyl-theophylline (200 nM) blocked the effects of adenosine. (nih.gov)
  • Materials and Methods: The expression of casps3 was measured by real-time polymerase chain reaction and then flow cytometery and MTT assay were used to assess the apoptotic and proliferation cell rate after the treatment of T47D cells with specific agonist N6-cyclopentyladenosine (CPA) and antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) of this receptor 24, 48, and 72 hours after treatment. (uitm.edu.my)
  • Investigation the Effect of Adenosine A1 Receptor Agonist and Antagonist on P53 Gene Expression, and Apoptosis Pathways and Rate in U87Mg Multiform Glioblastoma by: Fahimeh Zamani-Rarani, et al. (uitm.edu.my)
  • Bone marrow cells (BMCs) were harvested from C57Bl/6 female mice or A 1 R-knockout mice and their wild-type (WT) littermates and differentiated into osteoclasts in the presence of colony stimulating factor-1 and receptor activator of NF-κB ligand in the presence or absence of the A 1 R antagonist 1,3-dipropyl-8-cyclopentyl xanthine (DPCPX). (elsevierpure.com)
  • Methods: Intravital videomicroscopy of the rat jejunum was used to record the vascular responses of inflow (termed 1A) arterioles, proximal (p3A), and distal (d3A) premucosal arterioles during exposure to isotonic glucose or mannitol solutions alone or in the presence of the selective nitric oxide synthase (NOS) inhibitor (L-NMMA), an adenosine A1 receptor antagonist (8-cyclopentyl-1,3-dipropylxanthine (DPCPX)), or a K + ATP channel inhibitor (glibenclamide). (arizona.edu)
  • Simultaneous application of both the NOS inhibitor and the adenosine A1 receptor antagonist gave the same reduction in glucose-induced dilation of the premucosal arterioles as the adenosine A1 receptor antagonist alone. (arizona.edu)
  • Pre-treatment with pertussis toxin (Gi/o-protein inhibitor), DPCPX (A1 adenosine receptor antagonist) or TG2 inhibitors (Z-DON and R283) attenuated the A1 adenosine receptor-induced pharmacological pre- and post-conditioning. (ntu.ac.uk)
  • Caffeine, one of the most consumed central nervous system (CNS) stimulants, is an antagonist of A 1 and A 2A adenosine receptors. (frontiersin.org)
  • SLV 320 is a potent and selective adenosine A 1 receptor antagonist (K i values are 1, 200, 398 and 3981 nM at human A 1 , A 3 , A 2A and A 2B receptors respectively). (tocris.com)
  • Renal hemodynamics responses to ischemia-reperfusion injury in mongrel dog models were determined with or without multiple brief renal ischemic preconditioning treatments, as well as the adenosine A1 receptor antagonist (KW-3902), respectively. (eurekamag.com)
  • One 10-min IPC, adenosine A1 receptor antagonist (KW-3902) also shortened the recovery time of renal blood flow (RBF) and urine flow (UF), as well as mean blood pressure (BP). (eurekamag.com)
  • Caffeine (CAF), a nonselective adenosine A1 and A2A receptor antagonist and commonly used psychoactive substance, may affect these disorders in a dose-dependent manner. (aaem.pl)
  • Activation of the adenosine A1 receptor by an agonist causes binding of Gi1/2/3 or Go protein. (wikipedia.org)
  • N6-Cyclopentyladenosine N(6)-cyclohexyladenosine Tecadenoson is an effective A1 adenosine agonist, as is selodenoson. (wikipedia.org)
  • 3 A non-speci®c adenosine receptor agonist 2-chloroadenosine (CAD) resulted in biphasic response with a small contraction at lower concentrations (1079 ±1078 M) followed by a signi®cant relaxation at higher concentration in endothelium-intact SHR tissues suggesting presence of both A1 and A2 adenosine receptors in SHR aorta. (uncg.edu)
  • Development of an Adenosine A1 Receptor agonist, MRS5474 for the treatment of chronic depression Project Summary Depression is a common mental disorder, which can be chronic or recurrent, markedly tarnishing a person?s ability to function in their normal life. (grantome.com)
  • Aims: Neladenoson bialanate is a partial adenosine A1 receptor agonist with demonstrated beneficial effects on cardiac function in animal models. (unimib.it)
  • A1 adenosine receptor agonist), formoterol (β2-adrenoceptor agonist) or isoprenaline (non-selective β-adrenoceptor agonist) were added before hypoxia/reoxygenation (pre-conditioning) or at the start of reoxygenation following hypoxia (post-conditioning). (ntu.ac.uk)
  • The research by the team at Warwick, together with colleagues at the University of Cambridge, University of Bern, Monash University, Coventry University and industrial collaborators, is published in Nature Communications in a paper entitled "Selective activation of G?ob by an adenosine A1 receptor agonist elicits analgesia without cardiorespiratory depression. (sciencedaily.com)
  • 2-Cl-IB-MECA is a high affinity and extremely selective A 3 adenosine receptor agonist (K i = 0.33 nM). (rndsystems.com)
  • Hemodynamic effects of histamine release elicited by the selective adenosine A 3 receptor agonist 2-Cl-IB-MECA in conscious rats. (rndsystems.com)
  • An adenosine A3 receptor agonist inhibits DSS-induced colitis in mice through modulation of the NF-κB signaling pathway. (rndsystems.com)
  • Theophylline and caffeine are nonselective adenosine antagonists that are used to stimulate respiration in premature infants. (wikipedia.org)
  • Thus, it may prove more advantageous to use selective A1 antagonists to help reduce adenosine-induced brain injury. (wikipedia.org)
  • Therefore, adenosine A1 receptor antagonists may be introduced as anti-cancer agents. (uitm.edu.my)
  • Due to indirect modulation of dopamine transmission, adenosine receptor antagonists may be useful in either treating cocaine use or improving disrupted cognitive-behavioral functions associated with chronic cocaine use. (omicsonline.org)
  • These preliminary data raise the possibility that adenosine antagonists may affect cocaine-dependent and non-dependent subjects differently. (omicsonline.org)
  • 7 Endothelium-dependent contractions elicited by A1 receptor agonists were blocked by indomethacin and by free radical scavengers. (uncg.edu)
  • A1 receptors are implicated in sleep promotion by inhibiting wake-promoting cholinergic neurons in the basal forebrain. (wikipedia.org)
  • We used whole-cell patch-clamp recordings in in vitro rat brain slices to investigate the effect of adenosine on identified cholinergic and noncholinergic neurons of the magnocellular preoptic nucleus and substantia innominata. (nih.gov)
  • Adenosine was also tested on two groups of electrophysiologically distinct noncholinergic magnocellular preoptic nucleus and substantia innominata neurons. (nih.gov)
  • Blocking the H-current with ZD7288 (20 microM) abolished adenosine effects on these neurons. (nih.gov)
  • These results demonstrate that, in the magnocellular preoptic nucleus and substantia innominata region of the basal forebrain, adenosine inhibits both cholinergic neurons and a subset of noncholinergic neurons. (nih.gov)
  • Adenosine, a metabolite of ATP and a ubiquitous neuromodulator in the brain, is released from neurons and astrocytes in an activity-dependent manner. (jneurosci.org)
  • Adenosine is produced by neurons throughout the day as they fire, and as more of it is produced, the more your nervous system ratchets down," he explains. (todoist.com)
  • Basal adenosine modulates the functional properties of AMPA receptors in mouse hippocampal neurons through the activation of A1R A2AR and A3R. (rndsystems.com)
  • CXCL16 orchestrates adenosine A3 receptor and MCP-1/CCL2 activity to protect neurons from excitotoxic cell death in the CNS. (rndsystems.com)
  • citation needed] Caffeine, as well as theophylline, has been found to antagonize both A1 and A2A receptors in the brain. (wikipedia.org)
  • Intraperitoneal (panels A and B), intrathecal (panels C and D), and intraplantar (panels E and F) pretreatment with caffeine and the antihyperalgesic effect of 9 minutes of ankle joint mobilization (AJM) or adenosine (30 mg/kg, i.p.) in mice. (highwire.org)
  • To compare and contrast the stimulant effects of adenosine antagonism to direct dopamine stimulation, we administered 150 mg and 300 mg caffeine, 20 mg amphetamine, and placebo to cocaine-dependent vs. healthy control subjects, matched on moderate caffeine use. (omicsonline.org)
  • The intake of caffeine effectively blocks adenosine intake by entering the A1 receptor but not activating it. (todoist.com)
  • Acting as an adenosine inhibitor, caffeine can also wreak havoc on your sleep schedule. (todoist.com)
  • Caffeine has antiarrhythmic properties through adenosine A1 and A2A receptor inhibition, hence the difference in effects of decaf vs full strength coffee on heart rhythm disorders," Kistler explained. (medscape.com)
  • In the basal forebrain, adenosine accumulates during wakefulness and, when locally applied, suppresses neuronal activity and promotes sleep. (nih.gov)
  • Because a reduction in A1 expression appears to prevent hypoxia-induced ventriculomegaly and loss of white matter, the pharmacological blockade of A1 may have clinical utility. (wikipedia.org)
  • Adenosine A1 receptor blockade completely prevented glucose-induced dilation of the premucosal arterioles. (arizona.edu)
  • Here we show that at neocortical synapses in slices from rat visual cortex, adenosine modulates the weight dependence of heterosynaptic plasticity: blockade of adenosine A 1 receptors abolished weight dependence, while increased adenosine level strengthened it. (jneurosci.org)
  • blockade of adenosine A1 receptors abolished it. (jneurosci.org)
  • Blockade of transport receptors may alter tissue exposure (eg, diuresis from blockade of adenosine A1 receptors, such as with aminophylline, may decrease exposure). (msdmanuals.com)
  • Sacubitril/valsartan (Entresto), an angiotensin receptor-neprilysin inhibitor (ARNI), was approved by the FDA in July 2015 to reduce the risk of cardiovascular death and hospitalization for heart failure in patients with congestive heart failure (New York Heart Association [NYHA] class II-IV) and reduced ejection fraction. (medscape.com)
  • Neuromodulatory transmitters engage G-protein coupled receptors (GPCRs), activating intracellular signaling cascades that then can directly activate or modify the properties of ion channels. (frontiersin.org)
  • abstract = "Adenosine regulates a wide variety of physiological processes via interaction with one or more G-protein-coupled receptors (A1R, A 2AR, A2BR, and A3R). (elsevierpure.com)
  • In the first group adenosine, via activation of postsynaptic A1 receptors, reduced spontaneous firing via inhibition of the hyperpolarization-activated cation current. (nih.gov)
  • The aim of this study was to evaluate the effect of the A1 receptor function on cell programmed death or proliferation, as well as the relationship between this receptor stimulation/inhibition and caspase 3 (casp3) expression in T47D cell line that has a mutant and non-functional P53 gene. (uitm.edu.my)
  • Inhibition of erythroblast growth and fetal hemoglobin production by ribofuranose-substituted adenosine derivatives. (rndsystems.com)
  • 1 Isolated aortic rings (endothelium-intact and -denuded) from spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats were used in this study to examine the vasoactive e ects of various adenosine analogues. (uncg.edu)
  • 8 These data suggest that the contractile response to adenosine analogues in SHR aorta is probably mediated by free radicals which are generated through the increased cyclo-oxygenase ctivity occurring in the vascular endothelium of SHR but not the WKY rats. (uncg.edu)
  • In contrast, mNT5E had no antinociceptive effects when injected intrathecally into adenosine A 1 receptor ( A 1 R, Adora1 ) knockout mice. (biomedcentral.com)
  • Background: Both nitric oxide (NO) and adenosine A1 receptor activation mediate microvascular vasodilation during intestinal glucose absorption. (arizona.edu)
  • The P2X4 and P2X7 receptors are involved in microglia chemotaxis and activation processes. (unicam.it)
  • The possible role of this receptor could be related to the cytoskeletal rearrangement of microglia occurring in migration or activation processes, as it has been also suggested recently for A2AAR. (unicam.it)
  • Clopidogrel exerts its antiplatelet effect by inhibiting the binding of adenosine diphosphate (ADP) to its receptor (P2Y12) and consequent ADP-mediated platelet activation [ 3 ]. (hindawi.com)
  • renal adenosine A1 receptor activation during the renal ischemia-reperfusion injury is detrimental to renal function. (eurekamag.com)
  • To this end, respiration of unrestrained adult and neonatal adenosine A1 receptor knockout mice (A(1)R(-/-)) was measured in a plethysmographic device. (uni-regensburg.de)
  • In conclusion, these data indicate that the adenosine A(1) receptor is an important molecular component mediating hypoxic depression in adult mice and it appears to stabilize respiration of neonatal mice. (uni-regensburg.de)
  • In particular, sleep deprivation upregulates adenosine A1 receptors (A1R) in mice and humans. (grantome.com)
  • Podocyte Density and Albuminuria in Aging Diabetic Ins2± Mice with or Without Adenosine A1 Receptor Signaling. (nih.gov)
  • Neonatal exposure to a Type-I pyrethroid (bioallethrin) induces dose-response changes in brain muscarinic receptors and behaviour in neonatal and adult mice. (cdc.gov)
  • The adenosine signaling pathway activated by sleep deprivation has shown rapid benefits in preclinical and clinical studies. (grantome.com)
  • Because adenosine tone is a natural correlate of activity level (activity increases adenosine tone) and brain state (elevated adenosine tone increases sleep pressure), modulation of heterosynaptic plasticity by adenosine represents an endogenous mechanism that translates changes of the brain state into a shift of the regime of synaptic plasticity and learning. (jneurosci.org)
  • We speculate that adenosine modulation may provide a mechanism for fine-tuning of plasticity and learning according to brain state and activity. (jneurosci.org)
  • Beyond supporting spatial orientation within rat brains especially autoradiographic images may serve as a base to quantitatively evaluate the complex uptake patterns of microPET studies with receptor ligands or tumor tracers. (kobv.de)
  • Adenosine A 3 receptors: novel ligands and paradoxical effects. (rndsystems.com)
  • Adenosine regulates a wide variety of physiological processes via interaction with one or more G-protein-coupled receptors (A 1 R, A 2A R, A 2B R, and A 3 R). Because A 1 R occupancy promotes fusion of human monocytes to form giant cells in vitro, we determined whether A 1 R occupancy similarly promotes osteoclast function and formation. (elsevierpure.com)
  • Stimulation of the A1 receptor has a myocardial depressant effect by decreasing the conduction of electrical impulses and suppressing pacemaker cell function, resulting in a decrease in heart rate. (wikipedia.org)
  • Insufficient hepatic O 2 in animal and human studies has been shown to elicit a hepatorenal reflex in response to increased hepatic adenosine, resulting in the stimulation of renal as well as muscle sympathetic nerve activity and activating the renin angiotensin system. (surgicalneurologyint.com)
  • Ecto-5'-nucleotidase (NT5E, also known as CD73) hydrolyzes extracellular adenosine 5'-monophosphate (AMP) to adenosine in nociceptive circuits. (biomedcentral.com)
  • Ecto-5'-nucleotidase (NT5E) is a glycosyl phosphatidylinositol (GPI)-anchored membrane protein that catalyzes the hydrolysis of extracellular AMP to adenosine [ 1 ]. (biomedcentral.com)
  • Endogenous extracellular adenosine level fluctuates in an activity-dependent manner and with sleep-wake cycle, modulating synaptic transmission and short-term plasticity. (jneurosci.org)
  • The nucleoside adenosine has been implicated in the regulation of respiration, especially during hypoxia in the newborn. (uni-regensburg.de)
  • These results have shown that A1 adenosine receptor and β2-adrenoceptor-induced protection against simulated hypoxia/reoxygenation occurs in a TG2 and Gi/o-protein dependent manner in H9c2 cardiomyoblasts. (ntu.ac.uk)
  • The primary aim of this study was to determine the role of TG2 in A1 adenosine receptor and β2-adrenoceptor-induced pharmacological pre- and post-conditioning in the H9c2 cells. (ntu.ac.uk)
  • Examination of cyproheptadine in radioligand receptor-binding assays shoed that it was some five orders of magnitude more active in displacing appropriate radioligands from central histamine, 5-HT-2 and muscarinic cholinergic receptor sites than in inhibiting depolarization dependent calcium fluxes (Donatsch et al 1980). (erowid.org)
  • Characterization of ERK1/2 signalling pathways induced by adenosine receptor subtypes in newborn rat cardiomyocytes. (rndsystems.com)
  • Background: Adenosine receptor family, especially A1 type is-overexpressed in breast-derived tumor cells and the P53 gene is mutant in some of these cells while the casps gene is of wild type as well. (uitm.edu.my)
  • The protein encoded by this gene is an adenosine receptor that belongs to the G-protein coupled receptor 1 family. (antikoerper-online.de)
  • Vericiguat stimulates sGC, the intracellular receptor for endogenous NO, which catalyzes cyclic guanosine monophosphate (cGMP) production. (medscape.com)
  • Our overall hypothesis is that adenosine triphosphate (ATP) utilization during glucose absorption would increase adenosine metabolite release, which acts on adenosine A1 receptors to alter endothelial production of NO and/or activate ATP-dependent potassium channels (K + ATP ) to dilate intestinal microvessels. (arizona.edu)
  • To investigate the effects of renal ischemic preconditioning (IPC) on both renal hemodynamics and the renal interstitial concentrations of adenosine and adenine nucleotides induced by ischemia-reperfusion injury. (eurekamag.com)
  • The renal interstitial concentrations of adenosine and adenine nucleotides in response to ischemia-reperfusion injury, either following 1-3 cycles of IPC or not, were measured simultaneously using microdialysis sampling technology. (eurekamag.com)
  • Advanced renal IPC attenuated the increment of adenosine and adenine nucleotides, as well as recovery time during the 60-min reperfusion which followed the 60-min renal ischemia. (eurekamag.com)
  • The renal interstitial concentrations of adenosine and adenine nucleotides increased and decreased during renal ischemia and reperfusion, respectively. (eurekamag.com)
  • The adenosine A1 receptor is one member of the adenosine receptor group of G protein-coupled receptors with adenosine as endogenous ligand. (wikipedia.org)
  • These data suggested that spinal delivery of PAP protein could be used therapeutically to generate adenosine and activate A 1 R over an extended time period. (biomedcentral.com)
  • Considering that both PAP and NT5E generate adenosine, we hypothesized that NT5E protein might also have A 1 R-dependent antinociceptive effects. (biomedcentral.com)
  • Hence, a method is described for quantifying various receptor protein systems in the tumour as well as in the marginal invasive zones around experimentally implanted rat brain tumours and their representation in the tumour microenvironment as well as in 3D space. (kobv.de)
  • In F98 animals, a significant increase in A1AR receptor protein was found in the Peritumoural zone as a function of time of tumour development and tumour volume. (kobv.de)
  • Moreover, neuromodulators control the activity of these proteins through G-protein coupled receptor signaling cascades. (frontiersin.org)
  • In this study the role of adenosine A(1) receptors for the control of respiration was investigated in vivo. (uni-regensburg.de)
  • Finally, we attempted to assign a function to this receptor through an in vivo electrophysiological approach. (unicam.it)
  • Since adenosine has antinociceptive effects in rodents and humans, we hypothesized that NT5E, an enzyme that generates adenosine, might also have antinociceptive effects in vivo . (biomedcentral.com)
  • The type A1 receptors inhibit adenylyl cyclase, and play a role in the fertilization process. (antikoerper-online.de)
  • SLV320 to inhibit adenosine A1 receptor in piglet afferent arteriole. (tocris.com)
  • To inhibit adenosine A1 receptor in isolated pig afferent arteriole from kidney. (tocris.com)
  • This effect on the A1 receptor also explains why there is a brief moment of cardiac standstill when adenosine is administered as a rapid IV push during cardiac resuscitation. (wikipedia.org)
  • However, in altered cardiac function, such as hypoperfusion caused by hypotension, heart attack or cardiac arrest caused by nonperfusing bradycardias, adenosine has a negative effect on physiological functioning by preventing necessary compensatory increases in heart rate and blood pressure that attempt to maintain cerebral perfusion. (wikipedia.org)
  • Adenosine has been proposed as a homeostatic "sleep factor" that promotes the transition from waking to sleep by affecting several sleep-wake regulatory systems. (nih.gov)
  • Simultaneous Determination of Adenosine, Inosine, Hypoxanthine, Xanthine, and Uric Acid in Microdialysis Samples Using Microbore Column High-Performance Liquid Chromat. (doximity.com)
  • Exhibits high selectivity over the Na + -independent adenosine transporter. (rndsystems.com)
  • 2-Substitution of N 6 -benzyladenosine-5'-uronamides enhances selectivity for A 3 adenosine receptors. (rndsystems.com)
  • Brains were cryosliced and radio-labelled with a ligand of the peripheral type benzodiazepine-receptor (pBR), 3H-Pk11195 [(1-(2-chlorophenyl)-N-methyl-N-(1-methyl-propylene)-3-isoquinoline-carboxamide)] by receptor autoradiography. (kobv.de)
  • Indeed, while the role of A1AR on macrophages/microglia in several CNS diseases has been reported, recent important data suggested that neither resting nor LPS-activated microglia express this receptor. (unicam.it)
  • The data showed that the A1AR receptor is expressed by microglial cells and is positively regulated by ATP. (unicam.it)
  • These three different regions were transferred onto other adjacent slices that had been labelled by receptor autoradiography with the A1 Adenosine receptor (A1AR)-ligand 3H-CPFPX (3H-8-cyclopentyl-3-(3-fluorpropyl)-1-propylxanthine) for quantitative assessment of A1AR in the three different tumour zones. (kobv.de)
  • [ 135 ] In 2021, this indication was expanded to include heart failure in adults with preserved ejection fraction based on the PARAGON-HF (Prospective Comparison of ARNI with ARB [angiotensin-receptor blockers] Global Outcomes in HF with Preserved Ejection Fraction) study. (medscape.com)
  • Adenosine (0.5-100 microM) reduced the magnocellular preoptic nucleus and substantia innominata cholinergic neuronal firing rate by activating an inwardly rectifying potassium current that reversed at -82 mV and was blocked by barium (100 microM). (nih.gov)
  • Adenosine A1 receptors (A1R) play a key role in neuroprotection and enhanced AA1R function has shown antidepressant effects in preclinical and clinical studies. (grantome.com)
  • These studies suggest a critical role for adenosine in bone homeostasis via interaction with adenosine A 1 R and further suggest that A 1 R may be a novel pharmacologic target to prevent the bone loss associated with inflammatory diseases and menopause. (elsevierpure.com)
  • Animal studies also suggest a role for A1 receptors in kidney function and ethanol intoxication. (antikoerper-online.de)
  • 5 Removal of endothelium abolished the adenosine analogue induced contractions in SHR aorta nd attenuated the vasorelaxation responses in the WKY and SHR. (uncg.edu)
  • Bisoprolol is a highly selective beta1-adrenergic receptor blocker that decreases the automaticity of contractions. (medscape.com)
  • Season primes the brain in an arctic hibernator to facilitate entrance into torpor mediated by adenosine A(1) receptors. (rndsystems.com)
  • Adenosine limits the therapeutic effectiveness of anti-CTLA4 mAb in a mouse melanoma model. (rndsystems.com)
  • Both of these effects occur via postsynaptic A1 receptors, but are mediated downstream by two separate mechanisms. (nih.gov)
  • KATP channels and memory of ischemic preconditioning in dogs: synergism between adenosine and KATP channels. (doximity.com)
  • Recently, it has been demonstrated that also adenosine A2A receptors (A2AARs) are over-expressed in LPS-activated microglia and mediate microglial process retraction. (unicam.it)
  • White bars show the operated (control) + saline (10 mL/kg, i.p.) group or the antihyperalgesic effect of 9 minutes of AJM or adenosine (30 mg/kg, i.p. (highwire.org)
  • The aim of this study was to evaluate the effect of the A1 receptor function on cell programmed dea. (uitm.edu.my)
  • Pulsed electromagnetic fields increased the anti-inflammatory effect of A 2 A and A 3 adenosine receptors in human T/C-28a2 chondrocytes and hFOB 1.19 osteoblasts. (rndsystems.com)
  • Het rapport bespreekt de laatste onderzoeken naar het effect van koffie op de slaap en suggereert dat het drinken van koffie vroeg op de dag de alertheid en concentratie niveaus ondersteund, voornamelijk wanneer slaappatronen zijn verstoord. (koffieengezondheid.nl)
  • The adenosine A1 receptor has been found to be ubiquitous throughout the entire body. (wikipedia.org)