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.
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.
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.
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.
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.

Analysis of a ubiquitous promoter element in a primitive eukaryote: early evolution of the initiator element. (1/6258)

Typical metazoan core promoter elements, such as TATA boxes and Inr motifs, have yet to be identified in early-evolving eukaryotes, underscoring the extensive divergence of these organisms. Towards the identification of core promoters in protists, we have studied transcription of protein-encoding genes in one of the earliest-diverging lineages of Eukaryota, that represented by the parasitic protist Trichomonas vaginalis. A highly conserved element, comprised of a motif similar to a metazoan initiator (Inr) element, surrounds the start site of transcription in all examined T. vaginalis genes. In contrast, a metazoan-like TATA element appears to be absent in trichomonad promoters. We demonstrate that the conserved motif found in T. vaginalis protein-encoding genes is an Inr promoter element. This trichomonad Inr is essential for transcription, responsible for accurate start site selection, and interchangeable between genes, demonstrating its role as a core promoter element. The sequence requirements of the trichomonad Inr are similar to metazoan Inrs and can be replaced by a mammalian Inr. These studies show that the Inr is a ubiquitous, core promoter element for protein-encoding genes in an early-evolving eukaryote. Functional and structural similarities between this protist Inr and the metazoan Inr strongly indicate that the Inr promoter element evolved early in eukaryotic evolution.  (+info)

Expression of both P1 and P2 purine receptor genes by human articular chondrocytes and profile of ligand-mediated prostaglandin E2 release. (2/6258)

OBJECTIVE: To assess the expression and function of purine receptors in articular chondrocytes. METHODS: Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to screen human chondrocyte RNA for expression of P1 and P2 purine receptor subtypes. Purine-stimulated prostaglandin E2 (PGE2) release from chondrocytes, untreated or treated with recombinant human interleukin-1alpha (rHuIL-1alpha), was assessed by radioimmunoassay. RESULTS: RT-PCR demonstrated that human articular chondrocytes transcribe messenger RNA for the P1 receptor subtypes A2a and A2b and the P2 receptor subtype P2Y2, but not for the P1 receptor subtypes A1 and A3. The P1 receptor agonists adenosine and 5'-N-ethylcarboxamidoadenosine did not change PGE2 release from chondrocytes. The P2Y2 agonists ATP and UTP stimulated a small release of PGE2 that was potentiated after pretreatment with rHuIL-1alpha. PGE2 release in response to ATP and UTP cotreatment was not additive, but release in response to coaddition of ATP and bradykinin (BK) or UTP and BK was additive, consistent with ATP and UTP competition for the same receptor site. The potentiation of PGE2 release in response to ATP and UTP after rHuIL-1alpha pretreatment was mimicked by phorbol myristate acetate. CONCLUSION: Human chondrocytes express both P1 and P2 purine receptor subtypes. The function of the P1 receptor subtype is not yet known, but stimulation of the P2Y2 receptor increases IL-1-mediated PGE2 release.  (+info)

Presynaptic action of adenosine on a 4-aminopyridine-sensitive current in the rat carotid body. (3/6258)

1. Plasma adenosine concentration increases during hypoxia to a level that excites carotid body chemoreceptors by an undetermined mechanism. We have examined this further by determining the electrophysiological responses to exogenous adenosine of sinus nerve chemoafferents in vitro and of whole-cell currents in isolated type I cells. 2. Steady-state, single-fibre chemoafferent discharge was increased approximately 5-fold above basal levels by 100 microM adenosine. This adenosine-stimulated discharge was reversibly and increasingly reduced by methoxyverapamil (D600, 100 microM), by application of nickel chloride (Ni2+, 2 mM) and by removal of extracellular Ca2+. These effects strongly suggest a presynaptic, excitatory action of adenosine on type I cells of the carotid body. 3. Adenosine decreased whole-cell outward currents at membrane potentials above -40 mV in isolated type I cells recorded during superfusion with bicarbonate-buffered saline solution at 34-36 C. This effect was reversible and concentration dependent with a maximal effect at 10 microM. 4. The degree of current inhibition induced by 10 microM adenosine was voltage independent (45.39 +/- 2. 55 % (mean +/- s.e.m.) between -40 and +30 mV) and largely ( approximately 75 %), but not entirely, Ca2+ independent. 4-Aminopyridine (4-AP, 5 mM) decreased the amplitude of the control outward current by 80.60 +/- 3.67 % and abolished the effect of adenosine. 5. Adenosine was without effect upon currents near the resting membrane potential of approximately -55 mV and did not induce depolarization in current-clamp experiments. 6. We conclude that adenosine acts to inhibit a 4-AP-sensitive current in isolated type I cells of the rat carotid body and suggest that this mechanism contributes to the chemoexcitatory effect of adenosine in the whole carotid body.  (+info)

A comparison of an A1 adenosine receptor agonist (CVT-510) with diltiazem for slowing of AV nodal conduction in guinea-pig. (4/6258)

1. The purpose of this study was to compare the pharmacological properties (i.e. the AV nodal depressant, vasodilator, and inotropic effects) of two AV nodal blocking agents belonging to different drug classes; a novel A1 adenosine receptor (A1 receptor) agonist, N-(3(R)-tetrahydrofuranyl)-6-aminopurine riboside (CVT-510), and the prototypical calcium channel blocker diltiazem. 2. In the atrial-paced isolated heart, CVT-510 was approximately 5 fold more potent to prolong the stimulus-to-His bundle (S-H interval), a measure of slowing AV nodal conduction (EC50 = 41 nM) than to increase coronary conductance (EC50 = 200 nM). At concentrations of CVT-510 (40 nM) and diltiazem (1 microM) that caused equal prolongation of S-H interval (approximately 10 ms), diltiazem, but not CVT-510, significantly reduced left ventricular developed pressure (LVP) and markedly increased coronary conductance. CVT-510 shortened atrial (EC50 = 73 nM) but not the ventricular monophasic action potentials (MAP). 3. In atrial-paced anaesthetized guinea-pigs, intravenous infusions of CVT-510 and diltiazem caused nearly equal prolongations of P-R interval. However, diltiazem, but not CVT-510, significantly reduced mean arterial blood pressure. 4. Both CVT-510 and diltiazem prolonged S-H interval, i.e., slowed AV nodal conduction. However, the A1 receptor-selective agonist CVT-510 did so without causing the negative inotropic, vasodilator, and hypotensive effects associated with diltiazem. Because CVT-510 did not affect the ventricular action potential, it is unlikely that this agonist will have a proarrythmic action in ventricular myocardium.  (+info)

A new synthesis of 5'-deoxy-8,5'-cyclo-adenosine and -inosine: conformationally-fixed purine nucleosides (nucleosides and nucleotides. XVI). (5/6258)

A versatile method for the synthesis of 5'-deoxy-8,5'-cycloadenosine, a conformationally-fixed "anti" type of adenosine, was presented. Irradiation of 2', 3'-O-isopropylidene-5'-deoxy-5'-phenylthioadenosine with 60W Hg vapor lamp afforded 2',3'-O-isopropylidene-5'-deoxy-8,5'-cycloadenosine in high yield. The use of other 5'-alkylthio derivatives also gave the cycloadenosine, though the yields were rather poor. Deacetonation of the cyclocompound with 0.1N HCl gave 5'-deoxy-8,5'-cycloadenosine. The cycloinosine derivative was similarly prepared. The nmr, mass and CD spectra of 5'-deoxy-8,5'-cycloadenosine were given and discussed with the previously reported results.  (+info)

End group of naturally terminated and UV lesion terminated T7 in vitro RNA. (6/6258)

The 3' terminal nucleosides of RNA transcribed in vitro by E. coli RNA polymerase from T7 DNA and UV irradiated TN DNA were determined. The 3' terminal nucleoside of naturally terminated (t1 termination site) RNA cytidine. In the case of RNA terminated at UV lesions, it is cytidine in 0 per cent of the molecules and adenosine in the remaining 30 per cent. Cytidine trialcohols are labile in high concentrations of KOH and at high temperature and appear to convert to uridine.  (+info)

Nucleoside-3'-phosphotriesters as key intermediates for the oligoribonucleotide synthesis. III. An improved preparation of nucleoside 3'-phosphotriesters, their 1H NMR characterization and new conditions for removal of 2-cyanoethyl group. (7/6258)

An improved procedure for the transformation of 5'-O-monomethoxytrityl-2'-O-acetyl-3'-phosphates of uridine la, inosine ib and 6-N-benzoyladenosine lc into corresponding 3'/2,2,2-trichloroethyl, 2-cyanoethyl/-phosphates iiaic is reported. H NMR characterization of nucleoside 3'-phosphotriesters is presented. New conditions i.e. anhydrous triethylamine-pyridine treatment have been found for the selective removal of 2-cyanoethyl group from nucleoside 3'-phosphotriesters in the presence of neighbouring 2'-O-acetyl one.  (+info)

Electrophysiologic effects of adenosine in patients with supraventricular tachycardia. (8/6258)

BACKGROUND: We correlated the electrophysiologic (EP) effects of adenosine with tachycardia mechanisms in patients with supraventricular tachycardias (SVT). METHODS AND RESULTS: Adenosine was administered to 229 patients with SVTs during EP study: atrioventricular (AV) reentry (AVRT; n=59), typical atrioventricular node reentry (AVNRT; n=82), atypical AVNRT (n=13), permanent junctional reciprocating tachycardia (PJRT; n=12), atrial tachycardia (AT; n=53), and inappropriate sinus tachycardia (IST; n=10). There was no difference in incidence of tachycardia termination at the AV node in AVRT (85%) versus AVNRT (86%) after adenosine, but patients with AVRT showed increases in the ventriculoatrial (VA) intervals (13%) compared with typical AVNRT (0%), P<0.005. Changes in atrial, AV, or VA intervals after adenosine did not predict the mode of termination of long R-P tachycardias. For patients with AT, there was no correlation with location of the atrial focus and adenosine response. AV block after adenosine was only observed in AT patients (27%) or IST (30%). Patients with IST showed atrial cycle length increases after adenosine (P<0.05) with little change in activation sequence. The incidence of atrial fibrillation after adenosine was higher for those with AVRT (15%) compared with typical AVNRT (0%) P<0.001, or atypical AVNRT (0%) but similar to those with AT (11%) and PJRT (17%). CONCLUSIONS: The EP response to adenosine proved of limited value to identify the location of AT or SVT mechanisms. Features favoring AT were the presence of AV block or marked shortening of atrial cycle length before tachycardia suppression. Atrial fibrillation was more common after adenosine in patients with AVRT, PJRT, or AT. Patients with IST showed increases in cycle length with little change in atrial activation sequence after adenosine.  (+info)

This study demonstrates that three structurally distinct A1 receptor antagonists increase extracellular adenosine levels in two different types of cardiovascular cells, i.e., cardiac fibroblasts and vascular smooth muscle cells, and in two species, rats and humans. The extracellular adenosine responses to A1 receptor antagonists are concentration dependent, and are attenuated by pertussis toxin, a toxin that inactivates inhibitory G proteins, and by AMPCP, an inhibitor of ecto-5′-nucleotidase. This study also demonstrates that augmentation of extracellular adenosine levels attenuates the increase in extracellular adenosine induced by A1 receptor antagonists. Finally, this study shows that the effects of A1receptor antagonists on extracellular adenosine levels develop with a time lag of several hours.. Our working hypothesis is that high-affinity A1receptors detect elevated levels of adenosine in the biophase of the cell surface and engage a signal transduction process that ultimately decreases ...
TY - JOUR. T1 - Chronic exposure to adenosine receptor agonists and antagonists reciprocally regulates the A1 adenosine receptor-adenylyl cyclase system in cerebellar granule cells. AU - Hettinger-Smith, Barbara D.. AU - Leid, Mark. AU - Murray, Thomas F.. PY - 1996/11. Y1 - 1996/11. N2 - Chronic treatment with the adenosine receptor antagonist caffeine evokes an up-regulation of A1 adenosine receptors and increased coupling of the receptor to G proteins in rat brain membranes. However, chronic agonist exposure has not been explored. Primary cultures of cerebellar granule cells were exposed chronically to A1 adenosine receptor agonists and antagonists. Exposure to the A1 adenosine receptor agonist N6-cyclopentyladenosine resulted in (1) a time- and concentration-dependent reduction in the density of receptors labeled by 1,3[3H]dipropyl-8-cyclopentylxanthine, (2) an enhanced ability of guanyl nucleotides to decrease the fraction of A1 adenosine receptor sites displaying high affinity for ...
Background Adenosine is generated in response to cellular stress and damage and is elevated in the lungs of patients with chronic lung disease. Adenosine signaling through its cell surface receptors serves as an amplifier of chronic lung disorders, suggesting adenosine-based therapeutics may be beneficial in the treatment of lung diseases such as chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). Previous studies in mouse models of chronic lung disease demonstrate that the key components of adenosine metabolism and signaling are altered. Changes include an up-regulation of CD73, the major enzyme of adenosine production and down-regulation of adenosine deaminase (ADA), the major enzyme for adenosine metabolism. In addition, adenosine receptors are elevated. Methodology/Principal Findings The focus of this study was to utilize tissues from patients with COPD or IPF to examine whether changes in purinergic metabolism and signaling occur in human disease. Results
Intravenously administered adenosine is rapidly cleared from the circulation via cellular uptake, primarily by erythrocytes and vascular endothelial cells. This process involves a specific transmembrane nucleoside carrier system that is reversible, nonconcentrative, and bidirectionally symmetrical. Intracellular adenosine is rapidly metabolized either via phosphorylation to adenosine monophosphate by adenosine kinase, or via deamination to inosine by adenosine deaminase in the cytosol. Since adenosine kinase has a lower Km and Vmax than adenosine deaminase, deamination plays a significant role only when cytosolic adenosine saturates the phosphorylation pathway. Inosine formed by deamination of adenosine can leave the cell intact or can be degraded to hypoxanthine, xanthine, and ultimately uric acid. Adenosine monophosphate formed by phosphorylation of adenosine is incorporated into the high-energy phosphate pool. While extracellular adenosine is primarily cleared by cellular uptake with a ...
Adenosine is a candidate sleep substance. It can be both a distress signal of importance in pathology and a physiological regulator. Key factors in determining which of these possibilities pertain are: (i) the number of receptors expressed, and (ii) the mechanisms that establish extracellular adenosine levels. The roles of adenosine are studied by means of antagonists and/or animals (mostly mice) with targeted deletions of receptors or enzymes involved in adenosine metabolism. Whereas adaptive changes in the genetically modified mice can occur for the physiologically important effects, such adaptive changes are less likely to occur in situations where adenosine acts as a distress signal. The relevance to sleep will be covered only in general terms in this review and will be covered in other contributions to this volume.
Adenosine is 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. For instance, adenosine plays an important role in energy transfer - as adenosine triphosphate (ATP) and adenosine diphosphate (ADP). It also plays a role in signal transduction as cyclic adenosine monophosphate, cAMP. Adenosine itself is both a neurotransmitter and potent vasodilator. When administered intravenously, adenosine causes transient heart block in the AV node. Because of the effects of adenosine on AV node-dependent supraventricular tachycardia, adenosine is considered a class V antiarrhythmic agent ...
Having the ability to modulate lymphocyte entry into the central nervous system (CNS) would benefit patients with neuroinflammatory diseases. We have previously shown that extracellular adenosine regulates CNS entry of lymphocytes during experimental autoimmune encephalomyelitis (EAE), the animal model for the CNS inflammatory disease multiple sclerosis. For instance, while extracellular adenosine levels are vastly increased following inflammatory cellular damage (from the hydrolysis of released cytoplasimic ATP by CD39 and CD73), mice lacking CD73 or given adenosine receptor (AR) antagonists have significantly reduced CNS lymphocyte entry during EAE. We now show through detailed genetic studies that AR signaling regulates lymphocyte migration into the CNS though induction of CX3CL1, a specialized chemokine that acts as both an adhesion molecule and chemoattractant for lymphocytes, monocytes, and NK cells. We show that AR signaling is necessary and sufficient to induce CNS expression of CX3CL1 ...
Vasodilator stress with adenosine or dipyridamole is an alternative to exercise stress with myocardial perfusion imaging for the detection of coronary artery disease. Although the safety of adenosine and dipyridamole has been well established, undesirable side effects including chest pain, headache, dyspnea, and atrioventricular conduction abnormalities do occur in a majority of patients.1-4 In addition, both adenosine and dipyridamole produce severe bronchoconstriction when given to asthmatics. Because of its ultrashort half-life, adenosine must be administered by a constant IV infusion.. Whereas adenosine-induced coronary vasodilatation is mediated primarily by stimulation of the A2A receptor subtype on vascular smooth muscle, the side effects described above are believed to be caused by stimulation of 1 or more of the other 3 adenosine receptor subtypes, A1, A2B, and A3.5 The discovery of highly selective and relatively short-acting adenosine receptor A2A agonists6-9 has opened the ...
A concise synthesis of a series of N6-substituted adenosines with bicyclo[3.2.1]octan-6-yl and polycyclic N6-substituents has been developed. The adenosine A1 receptor (A1R) affinity and potency of these compounds was initially assessed using competitive binding assays and cyclic adenosine monophosphate (cAMP) accumulation assays in DDT1 MF-2 cells. The potency and receptor subtype selectivity of selected examples was further evaluated by measuring their effects on cAMP accumulation at all human adenosine receptor subtypes expressed in CHO cells. The results of these assays indicated that all of the synthesised N6-substituted adenosines are full agonists at A1R and activate this receptor selectively over the other adenosine receptor subtypes. The two standout compounds in terms of potency were N6-(3-thiabicyclo[3.2.1]octan-6-yl)adenosine and N6-(cubanylmethyl)adenosine with EC50 values at human A1R of 2.3 nM and 1.1 nM, respectively. The cubanylmethyl derivative in particular proved to be highly ...
We examined how the endogenous anticonvulsant adenosine might influence gamma-aminobutyric acid type A (GABA(A)) receptor stability and which adenosine receptors (ARs) were involved. Upon repetitive activation (GABA 500 microM), GABA(A) receptors, microtransplanted into Xenopus oocytes from neurosurgically resected epileptic human nervous tissues, exhibited an obvious GABA(A)-current (I(GABA)) run-down, which was consistently and significantly reduced by treatment with the nonselective adenosine receptor antagonist CGS15943 (100 nM) or with adenosine deaminase (ADA) (1 units/ml), that inactivates adenosine. It was also found that selective antagonists of A2B (MRS1706, 10 nM) or A3 (MRS1334, 30 nM) receptors reduced I(GABA) run-down, whereas treatment with the specific A1 receptor antagonist DPCPX (10 nM) was ineffective. The selective A2A receptor antagonist SCH58261 (10 nM) reduced or potentiated I(GABA) run-down in approximately 40% and approximately 20% of tested oocytes, respectively. The ...
Introduction: Prior studies demonstrate that ischemic preconditioning (IP) alters adenosine metabolism. The significance of this effect is not fully understood, but evidence suggests that reduction in extracellular adenosine may represent use as an alternative fuel. Transformation into AMP/ADP may also replenish intracellular total adenine nucleotides (TAN), improving the potential high-energy phosphate bonds available in cells facing ischemia. In both cases, adenosine supports cell energy requirements and may be a key component of IPs protective mechanisms. There are no previous studies of brain adenosine in human patients undergoing remote IP.. Methods: In adults with aneurysmal subarachnoid hemorrhage (SAH), 3-4 remote IP sessions were conducted on non-consecutive days, 4-12 days after hemorrhage. Each session consisted of 4 5-min cycles of lower extremity blood pressure cuff inflation to 30mmHg above systolic blood pressure, followed by 5-min reperfusion. Patients had microdialysis (MD) ...
To the Editor: Recently, Jeremias et al1 reported their studies comparing the vasodilator action of intracoronary injected adenosine with ATP in 6 healthy mongrel dogs. On the basis of a dose-response curve ranging from 10 to 100 μg, the authors conclude that adenosine and ATP are approximately equipotent vasodilators. Neither substance could induce maximal vasodilation, as assessed with postischemic hyperemia. Similar results were obtained by Kato et al2 in the human coronary vasculature using a single dose of adenosine and ATP (20 μg), without comparison with postischemic hyperemia. Both groups conclude that adenosine and ATP are equipotent coronary vasodilators and suggest that the ATP-induced vasodilation is caused by its degradation to AMP and adenosine, with subsequent stimulation of adenosine A2 receptors. We disagree their conclusions for the following 2 reasons:. 1. Equimolar doses of ATP and adenosine should be compared. The molecular weight of ATP is roughly twice that of adenosine ...
Intra- and extracellular adenosine levels rise in response to physiological stimuli and with metabolic/energetic perturbations, inflammatory challenge and tissue injury. Extracellular adenosine engages members of the G-protein coupled adenosine receptor (AR) family to mediate generally beneficial acute and adaptive responses within all constituent cells of the heart. In this way the four AR sub-types - A1, A2A, A2B, and A 3Rs - regulate myocardial contraction, heart rate and conduction, adrenergic control, coronary vascular tone, cardiac and vascular growth, inflammatory-vascular cell interactions, and cellular stress-resistance, injury and death. The AR sub-types exert both distinct and overlapping effects, and may interact in mediating these cardiovascular responses. The roles of the ARs in beneficial modulation of cardiac and vascular function, growth and stress-resistance render them attractive therapeutic targets. However, interactions between ARs and with other receptors, and their ubiquitous
TY - JOUR. T1 - Desensitization of A1 adenosine receptors in rat cerebral cortex. AU - Park, K. S.. AU - Yang, W. S.. AU - Kim, K. H.. PY - 1996. Y1 - 1996. N2 - Following the subcutaneous administration of R(-)N6-(2-phenylisopropyl)adenosine (600 nmol/kg/hr) to rats for 1 week using Alzet® mini-osmotic pumps, A1 adenosine receptor functions were determined using [3H]DPCPX binding, [365]GTP(γ)S binding, and adenylyl cyclase assays. A1 adenosine receptor binding and the inhibition of adenylyl cyclase activity by PIA was not altered in cerebrocortical membranes prepared from PIA-treated rats. However, there was a significant decrease in the A1 adenosine receptor-mediated stimulation of [35S]GTP(γ)S binding to cerebrocortical membranes prepared from PIA-treated rats (22.0% decrease in basal activity; 19.7% decrease in maximal activity). These results suggest that the desensitization of A1 adenosine receptors following chronic administration involves agonist-induced uncoupling of the receptors ...
Adenosine is an important mediator of the endogenous defense against ischemia-induced injury in the heart. Adenosine can achieve cardioprotection by mediating the effect of ischemic preconditioning and by protecting against myocyte injury when it is present during the infarct-producing ischemia. A novel adenosine A3 receptor can mediate this protective function. One approach to achieve cardioprotection is to enhance myocardial sensitivity to the endogenous adenosine by increasing the number of adenosine receptors instead of administering an adenosine receptor agonist. The objective of the present study was to investigate whether genetic manipulation of the cardiac myocyte, achieved by gene transfer and overexpression of the human A3 receptor cDNA, renders the myocytes resistant to the deleterious effect of ischemia. Prolonged hypoxia with glucose deprivation, causing myocyte injury and adenosine release, was used to simulate ischemia in cultured chick embryo ventricular myocytes. During simulated
In the heart, endogenous adenosine attenuates the beta-adrenergic-elicited increase in contractile performance via activation of adenosine A1 receptors. It has been recently reported that this function of adenosine becomes more pronounced with myocardial maturation. The purpose of the present study was to determine whether mature hearts possess a greater sensitivity than immature hearts to this antiadrenergic effect of adenosine. Isolated perfused hearts or atria from immature (ca. 23 days) and mature (ca. 80 days) rats were stimulated with isoproterenol (Iso), a beta-adrenergic agonist, at 10(-8) M and concomitantly exposed to increasing concentrations of 2-chloro-N6-cyclopentyladenosine (CCPA), a highly selective and potent adenosine A1-receptor agonist, from 10(-12) to 10(-6) M. CCPA at 10(-10)-10(-6) M dose dependently reduced the Iso-elicited contractile response more in immature than in mature hearts or atria. At 10(-6) M, CCPA reduced the Iso-elicited contractile response by 103% in immature
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We have demonstrated previously that both acute and chronic oral administration of adenosine have novel functions such as anti-hypertensive effects and improved hyperlipidaemia in stroke-prone spontaneously hypertensive rats (SHRSP) fed a normal diet. The purpose of the present study was to investigate the effect of adenosine administration on metabolic syndrome-related parameters in SHRSP fed a high-fat diet. Six-week-old rats were divided into three groups, and were administered either water (control) or adenosine (10 or 100 mg/l) for 8 weeks. During this period, the rats had free access to a high-fat diet based on AIN-93M. The results showed that hypertension, plasma lipid, NO, insulin, glucose and urinary 8-hydroxy-2-deoxyguanosine levels improved significantly in both adenosine groups. The mRNA expression levels of genes involved in anti-oxidative activity and adenosine receptors were also altered in the adenosine groups. Administration of adenosine also increased plasma adiponectin ...
Cyclic 3, 5-[14C]AMP was measured in platelets that had first been incubated with [14C]adenine. Maximum increases of 2-4-fold were observed 0.5 min after addition of 10-40 µM adenosine. Smaller increases were obtained with higher concentrations of adenosine. In 0.5-min incubations 2-chloroadenosine was less effective than adenosine at concentrations below 20 µM and more effective at concentrations above 100 µM. Incorporation of 1-10 µM adenosine into platelets was inhibited at least 96% by p-nitrobenzylthioguanosine without any effect on the increase in cyclic [14C]AMP caused by these concentrations of adenosine, suggesting that adenosine acts at an extracellular site. With higher adenosine concentrations, p-nitrobenzylthioguanosine was less effective in inhibiting incorporation of adenosine but blocked the decline in cyclic [14C]AMP levels observed on increasing the adenosine concentration above 40 µM. This inhibitory effect of high adenosine concentrations on the accumulation of cyclic ...
Each type of adenosine receptor has different functions, although with some overlap.[3] For instance, both A1 receptors and A2A play roles in the heart, regulating myocardial oxygen consumption and coronary blood flow, while the A2A receptor also has broader anti-inflammatory effects throughout the body.[4] These two receptors also have important roles in the brain,[5] regulating the release of other neurotransmitters such as dopamine and glutamate,[6][7][8] while the A2B and A3 receptors are located mainly peripherally and are involved in processes such as inflammation and immune responses. Most older compounds acting on adenosine receptors are nonselective, with the endogenous agonist adenosine being used in hospitals as treatment for severe tachycardia (rapid heart beat),[9] and acting directly to slow the heart through action on all four adenosine receptors in heart tissue,[10] as well as producing a sedative effect through action on A1 and A2A receptors in the brain. Xanthine derivatives ...
TY - ABST. T1 - Dose-dependent effect of caffeine on adenosine-induced myocardial stress perfusion in Rubidium-82 PET/CT. T2 - no influence of one cup of coffee on myocardial flow reserve. AU - Byrne, C.. AU - Kjaer, A.. AU - Wissenberg, M.. AU - Hurry, P. K.. AU - Schmedes, A. V.. AU - Forman, J. L.. AU - Hasbak, P.. PY - 2018. Y1 - 2018. U2 - 10.1093/eurheartj/ehy563.3007. DO - 10.1093/eurheartj/ehy563.3007. M3 - Conference abstract in journal. VL - 39. SP - 628. EP - 629. JO - European Heart Journal. JF - European Heart Journal. SN - 0195-668X. IS - suppl. 1. ER - ...
Regadenoson produced higher stress MBF than dipyridamole and adenosine (3.58 ± 0.58 vs. 2.81 ± 0.67 vs. 2.78 ± 0.61 ml/min/g, p = 0.0009 and p = 0.0008 respectively). Regadenoson had a much higher heart rate response than adenosine and dipyridamole respectively (95 ± 11 vs. 76 ± 13 vs. 86 ± 12 beats/ minute) When stress MBF was adjusted for heart rate, there were no differences between regadenoson and adenosine (37.8 ± 6 vs. 36.6 ± 4 μl/sec/g, p = NS), but differences between regadenoson and dipyridamole persisted (37.8 ± 6 vs. 32.6 ± 5 μl/sec/g, p = 0.03). The unadjusted MPR was higher with regadenoson (3.11 ± 0.63) when compared with adenosine (2.7 ± 0.61, p = 0.02) and when compared with dipyridamole (2.61 ± 0.57, p = 0.04). Similar to stress MBF, these differences in MPR between regadenoson and adenosine were abolished when adjusted for heart rate (2.04 ± 0.34 vs. 2.12 ± 0.27, p = NS), but persisted between regadenoson and dipyridamole (2.04 ± 0.34 vs. 1.77 ± 0.33, p = ...
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In the central nervous system, the nucleoside adenosine regulates neuronal activity by modulating the actions of other neurotransmitter systems, thereby influencing many different physiological processes and behaviors. Adenosinergic mechanisms are especially important in fine-tuning glutamatergic neurotransmission. Astrocytic release of adenosine triphosphate and its subsequent extracellular breakdown provides adenosine to drive homeostatic sleep. Acute ethanol (alcohol) exposure increases extracellular adenosine, which mediates the ataxic and hypnotic/sedative effects of alcohol, while chronic ethanol exposure leads to downregulated adenosine signaling that underlies insomnia, a major predictor of relapse. Adenosine gates glutamatergic input to the circadian clock located in the suprachiasmatic nucleus of the hypothalamus, modulating both photic (light-induced) and nonphotic (behaviorally-induced) synchronization of circadian activity rhythms. A recent study using mice lacking the equilibrative ...
Adenosine mediates many physiological functions via activation of extracellular receptors. The modulation of cell growth by adenosine was found to be receptor-mediated. In A431 cells adenosine evoked a biphasic response in which a low concentration (~10 μM) produced inhibition of colony formation but at higher concentrations (up to 100 μM) this inhibition was progressively reversed. Evidence for the involvement of A1 (inhibitory) and A2 (stimulatory) adenosine receptors in regulating cell growth of these tumor cells was obtained through plating efficiency studies based on the relative potency of adenosine agonists and antagonists. When both A1 and A2 receptors were blocked, colony formation or growth was not inhibited at low concentrations of adenosine but was inhibited at high adenosine concentrations ...
Objective. Adenosine infusion causes selective pulmonary vasodilation in fetal and neonatal lambs with pulmonary hypertension. We investigated the effects of a continuous infusion of adenosine on oxygenation in term infants with persistent pulmonary hypertension of newborn (PPHN).. Design. A randomized, placebo-controlled, masked trial comparing the efficacy of intravenous infusion of adenosine to normal saline infusion over a 24-hour period.. Setting. Inborn and outborn level III neonatal intensive care units at a university medical center.. Participants. Eighteen term infants with PPHN and arterial postductal Po2 of 60 to 100 Torr on inspired O2 concentration of 100% and optimal hyperventilation (PaCo2 ,30 Torr) were enrolled into the study. Study infants were randomly assigned to receive a placebo infusion of normal saline, or adenosine infusion in doses of 25 to 50 µg/kg/min over a 24-hour period.. Results. Nine infants each received adenosine or placebo. The two groups did not differ in ...
The initial studies to test the hypothesis that adenosine release mediates the anti-inflammatory effects of methotrexate were performed in vitro. In these studies, methotrexate treatment increased adenosine release from cultured endothelial cells and fibroblasts and the adenosine released diminished stimulated neutrophil adhesion to the monolayers of cultured cells (Cronstein et al., 1991). Subsequent in vivo studies confirmed the hypothesis that adenosine mediates the anti-inflammatory effects of methotrexate; pharmacologically relevant doses of methotrexate induce intracellular AICAR accumulation in splenocytes, increase adenosine concentrations in inflammatory exudates, and diminish leukocyte accumulation at an inflamed site (Cronstein et al., 1993). Moreover, the increase in exudate adenosine concentration was responsible for the anti-inflammatory effects of the drug since adenosine receptor antagonists or adenosine deaminase, an enzyme which converts adenosine to the receptor-inactive ...
Our work demonstrates that human endothelial cells of disparate origin are characterized by differential expression of adenosine receptor subtypes. HUVECs express mRNA for A2A and A2B receptors at a ratio of 10:1, and this preferential gene expression agrees well with the typical pharmacological phenotype of A2A receptor-mediated simulation of adenylate cyclase by adenosine analogs. Using complementary techniques, RT-PCR, and gene expression array, we found that A1 and A3 adenosine receptors are not expressed in HUVECs. Previous studies in HUVECs have suggested a potential role of A1 receptor in maintaining endothelial barrier function4 and of A1 and A3 receptors in modulation of tissue factors expression.6 The apparent contradiction between these results and ours can be explained by the use of nonselective concentrations of adenosine receptor ligands in previous studies.. HMEC-1 also express only A2A and A2B mRNA, but in contrast to HUVECs, they express predominantly A2B receptor mRNA, with a ...
Adenosine receptors (AR) belong to the G-protein coupled receptor family. There are four receptor subtypes: A1, A2A, A2B e A3. Adenosine receptor subtypes show a different distribution in the organism and are implicated in several physiopathological processes. In particular, antagonists towards A1AR are promising in the treatment of cognitive disorders. A2A antagonists seem to be involved in decrease the neurological impairment observed in Parkinson’s disease. A2B antagonists are potential therapeutic agents in asthma and diabetes. Finally, antagonists at the A3AR could be implicated in tumor growth inhibition and in glaucoma treatment. The crystallographic structure acquisition of the human A2A receptor allowed the design of new AR antagonists by the help of computational techniques. Our group is focused on the synthesis of new adenosine receptor antagonists (particularly towards A2A and A3) for their potential therapeutic use, but also as tools for pharmacological investigations on ...
Summary 1. The effect of the adenosine A2 receptor (AdoA2R) agonist N6-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)-ethyl]adenosine (DPMA) on adenosine A1 receptor (AdoA1R)-mediated negative inotropic responses was investigated in rat heart. 2. Hearts from male Wistar rats (250-350 g) were perfused with Krebs-Henseleit solution at constant flow in non-recirculating Langendorff mode. Hearts were paced at 5 Hz (5 ms duration, supramaximal voltage) via ventricular electrodes. After 30 min equilibration, (R)-N6-phenylisopropyl adenosine (R-PIA) concentration-response curves were constructed in the absence or presence of DPMA. 3. In paced hearts, R-PIA induced concentration-dependent decreases in triple product (heart rate נpeak systolic developed pressure נdP?/?dtmax), which were significantly attenuated by 1 nmol?/?L DPMA with a shift in pEC50 from 8.0 ᠰ.5 (n = 9) in control hearts to 6.63 ᠱ.03 (n = 5) in treated tissues (P , 0.05). The AdoA2AR antagonist 8-(3-chlorostyryl)caffeine (1 ...
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TY - JOUR. T1 - Modulating P1 Adenosine Receptors in Disease Progression of SOD1G93A Mutant Mice. AU - Armida, Monica. AU - Matteucci, Alessandra. AU - Pèzzola, Antonella. AU - Baqi, Younis. AU - Müller, Christa E. AU - Popoli, Patrizia. AU - Potenza, Rosa Luisa. PY - 2019/5. Y1 - 2019/5. N2 - Amyotrophic lateral sclerosis (ALS) is a fatal progressing neurodegenerative disease; to date, despite the intense research effort, only two therapeutic options, with very limited effects, are available. The purinergic system has been indicated as a possible new therapeutic target for ALS, but the results are often contradictory and generally confused. The present study was designed to determine whether P1 adenosine receptor ligands affected disease progression in a transgenic model of ALS. SOD1G93A mice were chronically treated, from presymptomatic stage, with a selective adenosine A2A receptor agonist (CGS21680), antagonist (KW6002) or the A1 receptor antagonist DPCPX. Body weight, motor performance ...
2 Biologic Description. Side effects requiring immediate medical attention. Adverse reactions to Adenosine of any severity reported in less than 1% of patients include: back discomfort, lower extremity discomfort, weakness, myocardial infarction, ventricular arrhythmia, third-degree AV block, bradycardia, palpitation, sinus exit block, sinus pause, T-wave changes, hypertension (systolic blood pressure > 200 mm Hg), drowsiness, emotional instability, tremors, blurred vision, dry mouth, ear discomfort, metallic taste, nasal congestion, scotomas, tongue discomfort. 1. Since Adenosine significantly increases blood flow in normal coronary arteries with little or no increase in stenotic arteries, Adenosine causes relatively less thallium-201 uptake in vascular territories supplied by stenotic coronary arteries i.e., a greater difference is seen after Adenosine between areas served by normal and areas served by stenotic vessels than is seen prior to Adenosine. Do not use in patients with ...
Adenosine is one of the bodys more powerful molecules and is linked to the digestion process. During digestion, the glucose in the foods we eat breaks down into glycolysis. This breaks down further into Adenosine Tri-Phosphate (ATP). This is responsible for energy transference between cells. After ATP is used up, it decomposes yet again into adenosine. As adenosine builds up in the bloodstream, it interacts with specific cell receptors, inhibiting neural activity and causing drowsiness.. What does this actually mean? Well, when the body runs out of fuel in the form of easily digestible sugars from the food we eat, adenosine signals the body to become drowsy. This essentially tells us to sleep and rebuild our energy reserves. Its a critical chain reaction that initiates the early stages of non-REM sleep and is essential to the natural sleep cycle.. ...
P>Adenosine is a well-described anti-inflammatory modulator of immune responses within peripheral tissues. Extracellular adenosine accumulates in inflamed and damaged tissues and inhibits the effector functions of various immune cell populations, including CD8 T cells. However, it remains unclear whether extracellular adenosine also regulates the initial activation of naive CD8 T cells by professional and semi-professional antigen-presenting cells, which determines their differentiation into effector or tolerant CD8 T cells, respectively. We show that adenosine inhibited the initial activation of murine naive CD8 T cells after alpha CD3/CD28-mediated stimulation. Adenosine caused inhibition of activation, cytokine production, metabolic activity, proliferation and ultimately effector differentiation of naive CD8 T cells. Remarkably, adenosine interfered efficiently with CD8 T-cell priming by professional antigen-presenting cells (dendritic cells) and semi-professional antigen-presenting cells ...
The review summarizes data evaluating the role of adenosine receptor signaling in murine hematopoietic functions. The studies carried out utilized either non-selective activation of adenosine receptors induced by elevation of extracellular adenosine or by administration of synthetic adenosine analogs having various proportions of selectivity for a particular receptor. Numerous studies have described stimulatory effects of non-selective activation of adenosine receptors, manifested as enhancement of proliferation of cells at various levels of the hematopoietic hierarchy. Subsequent experimental approaches, considering the hematopoiesis-modulating action of adenosine receptor agonists with a high level of selectivity to individual adenosine receptor subtypes, have revealed differential effects of various adenosine analogs. Whereas selective activation of A(1) receptors has resulted in suppression of proliferation of hematopoietic progenitor and precursor cells, that of A(3) receptors has led to ...
The effects of adenosine on inhibitory synaptic transmission in area CA1 were examined using the rat hippocampal slice preparation and intracellular recording. Adenosine did not change fast inhibitory synaptic potentials (IPSPs) but depressed late IPSPs evoked by direct activation of interneurons in the presence of 6,7-dinitroquinoxaline-2,3-dione (DNQX) and D,L-2-amino-5-phosphonovalerate (APV). Directly activated IPSPs were unchanged by the selective adenosine A1 receptor antagonist 8-cyclopentyltheophylline (CPT), but CPT reversed hyperpolarization and depression of late IPSPs produced by adenosine. These results indicate that adenosine depresses disynaptic IPSPs in area CA1 by decreasing synaptic activation of inhibitory neurons ...
Recent evidence suggests that ethanol initially causes an increase in receptor-dependent cAMP levels, followed by heterologous desensitization of receptors coupled to GS after chronic exposure. Here we investigated the role of adenosine in mediating these responses. We found that ethanol caused accumulation of extracellular adenosine in NG108-15 and S49 lymphoma cells. This adenosine activated adenosine receptors to increase intracellular cAMP levels. The addition of adenosine deaminase, to degrade accumulated extracellular adenosine, or isobutyl-methylxanthine, an adenosine receptor antagonist, completely blocked ethanol-induced increases in cAMP levels in NG108-15 cells. Chronic exposure of NG108-15 and S49 wild type cells to ethanol resulted in heterologous desensitization of adenosine receptor- and prostaglandin E1 receptor-dependent cAMP signal transduction. Coincubation of NG108-15 and S49 wild type cells with adenosine deaminase and ethanol for 48 hr prevented heterologous ...
Treatment with an adenosine uptake inhibitor attenuates glomerulonephritis in mice.: This study evaluated the effects of KF24345 (3-[1-(6,7-diethoxy-2-morpholin
Activation of protein kinase C (PKC) via adenosine receptors is known to be involved in the cardioprotection of ischemic preconditioning (IPC). Specifically, activation of PKCε is critical for cardioprotection. There is ample evidence that PKCε resides in cardiac mitochondria. However, the signals that promote translocation of PKCε are largely unknown. The present study was designed to determine whether and how adenosine receptor activation induces translocation of PKCε to mitochondria. Freshly isolated adult rat cardiac myocytes and rat heart-derived H9c2 were used in the study. Immunofluorescence imaging of isolated mitochondria showed that PKCε but not PKCδ was localized in mitochondria and this mitochondrial localization of PKCε was significantly increased by adenosine treatment. The adenosine-induced increase in PKCε-positive mitochondria was largely prevented not only by PKC inhibitor chelerythrine, but also by the HSP90 inhibitor geldanamycin and by siRNA targeting HSP90. ...
The adenosine A3 receptor, also known as ADORA3, is an adenosine receptor, but also denotes the human gene encoding it. Adenosine A3 receptors are G protein-coupled receptors that couple to Gi/Gq and are involved in a variety of intracellular signaling pathways and physiological functions. It mediates a sustained cardioprotective function during cardiac ischemia, it is involved in the inhibition of neutrophil degranulation in neutrophil-mediated tissue injury, it has been implicated in both neuroprotective and neurodegenerative effects, and it may also mediate both cell proliferation and cell death[citation needed]. Recent publications demonstrate that adenosine A3 receptor antagonists (SSR161421) could have therapeutic potential in bronchial asthma (17,18). Multiple transcript variants encoding different isoforms have been found for this gene. An adenosine A3 receptor agonist (CF-101) is in clinical trials for the treatment of rheumatoid arthritis. In a mouse model of infarction the A3 ...
In the current study, the combination of T62 and clonidine produced a synergistic interaction in rats with incisional pain. Synergy usually indicates that the two drugs have different final pathways to produce their effect, although other levels of interaction, such as altered drug disposition, can also be responsible. We did not measure tissue concentrations of drugs, so we cannot exclude a pharmacokinetic mechanism of synergy in the current study. Nonetheless, the observation of synergy is somewhat surprising if, as indicated by studies with spinal nerve ligation, the effect of T62 relies entirely on stimulating spinal norepinephrine release, which acts on α2adrenoceptors. One would in that case expect an additive interaction, and intrathecal adenosine and clonidine do interact additively in spinal-ligated rats. 14 In contrast, a synthetic adenosine agonist interacts synergistically with clonidine in acute thermal nociception tests in normal rats. 20 In addition, idazoxan only partially ...
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Definition of adenosine in the Financial Dictionary - by Free online English dictionary and encyclopedia. What is adenosine? Meaning of adenosine as a finance term. What does adenosine mean in finance?
Adenosine is a key metabolite involved in metabolic hyperemia in many vascular beds including coronary circulation, cerebral circulation, and skeletal muscle circulation.1 The roles of adenosine in vasculature are most prominent during hypoxia, ischemia, and reactive hyperemia.1 One important action of adenosine is to induce endothelium-dependent vasorelaxation.1-4 It is previously shown that, at least in some arteries, such as skeletal muscle arteries, a rise in [Ca2+]i is required for the endothelium-dependent vasorelaxation in response to adenosine.3-5 In the present study, we explored the possible role of CNG channels in adenosine-induced Ca2+ influx in vascular endothelial cells. Our results show that the adenosine-induced Ca2+ influx was markedly reduced by CNG-specific inhibitors L-cis-diltiazem and LY-83583 in H5V cells and in the primary cultured BAECs. Whole cell patch clamp recorded an adenosine-induced current that was sensitive to L-cis-diltiazem in both cell types. Furthermore, a ...
DESCRIPTION: (Adapted from the Investigators Abstract): Adenosine administered as an aerosol to asthmatics causes bronchoconstriction, while in non-asthmatics adenosine causes bronchodilation. This occurs because the activation of A2B adenosine receptors on sensitized mast cells triggers degranulation, releasing histamine, leukotrienes, and other allergic mediators. A2B adenosine receptors are blocked by theophylline, a xanthine that is effective in treating asthma. However, theophylline is a non-selective antagonist of all four adenosine receptor subtypes and produces side effects due primarily to A1 receptor blockade, including insomnia and diuresis. The incidence of asthma is increasing and current treatment options are limited. New drugs that are potent and selective antagonists of A2B adenosine receptors have great potential for the treatment of asthma and other allergic diseases. Adenosine Therapeutics, LLC owns the first potent and selective A2B antagonists. The purpose of this phase I ...
Objectives:. The overall goal of this proposal is to develop methods to achieve heart and vascular protection from ischemia and thus improve soldiers performance in adverse environment. The major hypothesis is that new approach and method can be developed to enhance resistance to stress-induced circulatory insufficiency and myocardial ischemia. The goals here are to determine whether a decreased adenosine transporter function is associated with a reduced physiological responsiveness to the vasculo-protective drug persantine using two in vitro endpoints: the ability of persantine 1) to inhibit platelet aggregation and 2) to inhibit [3H] uridine uptake. Both are endpoints that indicate physiological responsiveness. Both relate directly to the cardiovascular protective effects of , that is, persantine the availability of extracellular adenosine level and the anti-platelet property. Specifically, the relationship between circulating adenosine increase to persantine in vivo and blockade of ...
TY - JOUR. T1 - Attenuation of chronic pulmonary inflammation in A2B adenosine receptor knockout mice. AU - Zaynagetdinov, Rinat. AU - Ryzhov, Sergey. AU - Goldstein, Anna E.. AU - Yin, Huiyong. AU - Novitskiy, Sergey V.. AU - Goleniewska, Kasia. AU - Polosukhin, Vasiliy V.. AU - Newcomb, Dawn C.. AU - Mitchell, Daphne. AU - Morschl, Eva. AU - Zhou, Yang. AU - Blackburn, Michael R.. AU - Peebles, R. Stokes. AU - Biaggioni, Italo. AU - Feoktistov, Igor. PY - 2010/5/1. Y1 - 2010/5/1. N2 - Pharmacologic evidence suggests that activation of A2B adenosine receptors results in proinflammatory effects relevant to the progression of asthma, a chronic lung disease associated with elevated interstitial adenosine concentrations in the lung. This concept has been challenged by the finding that genetic removal of A2B receptors leads to exaggerated responses in models of acute inflammation. Therefore, the goal of our study was to determine the effects of A2B receptor gene ablation in the context of ...
Previous in vitro studies have shown biphasic effects of adenosine on mast cell activity; however, the receptor subtypes that mediate the inhibitory effects of adenosine are still controversial (Peachell et al., 1991; Yip et al., 2009). Mast cells express two distinct Gs-coupled adenosine receptors; their biologic roles have not been comprehensively defined, especially in vivo. Since activation of Gs-coupled adenosine receptors increases intracellular cAMP, we hypothesized that the inhibitory effects of adenosine on mast cells are mediated by the Gs-coupled adenosine receptors. In this study, we used both genetically modified animal models and mast cell cultures to comprehensively investigate the role of Gs-coupled adenosine receptors on mast cells both in vitro and in vivo. First, our data demonstrate a potent inhibitory effect of the nonhydrolyzable adenosine analog NECA on IgE-induced mast cell degranulation; this inhibitory effect of NECA was abolished by the genetic deletion of the A2B but ...
BACKGROUND: Increased sympathetic activity contributes to the progression of heart failure. Adenosine counteracts sympathetic activity by inhibition of presynaptic norepinephrine release and attenuation of the metabolic and contractile responses to beta-adrenergic stimulation. In this study, we tested the hypothesis that the adenosinergic effects (uptake blockade) of dipyridamole may retard the progression of pressure overload hypertrophy in the rat. METHODS AND RESULTS: To verify that the administration of dipyridamole increases myocardial adenosine levels in the rat, epicardial adenosine concentrations were measured from 12 isolated, perfused rat hearts exposed to 10(-7) and 10(-6) mol/l dipyridamole. Adenosine concentrations were increased with both doses of dipyridamole. Also, 9 weeks of dipyridamole treatment resulted in decreased sensitivity to the adenosine A1-receptor agonist, 2-chloro-N6-cyclopentyl adenosine, suggesting that dipyridamole increases adenosine levels in the intact rat. In ...
Adenosine is the first drug of choice in the treatment of supraventricular arrhythmias. While the effects of adenosine on sympathetic nerve activity (SNA) have been investigated, no information is available on the effects on cardiac vagal nerve activity (VNA). We assessed in rats the responses of cardiac VNA, SNA and cardiovascular variables to intravenous bolus administration of adenosine. in 34 urethane-anaesthetized rats, cardiac VNA or cervical preganglionic sympathetic fibres were recorded together with ECG, arterial pressure and ventilation, before and after administration of three doses of adenosine (100, 500 and 1000 mu g kg-1). the effects of adenosine were also assessed in isolated perfused hearts (n= 5). Adenosine induced marked bradycardia and hypotension, associated with a significant dose-dependent increase in VNA (+204 +/- 56%, P , 0.01; +275 +/- 120%, P , 0.01; and +372 +/- 78%, P , 0.01, for the three doses, respectively; n= 7). Muscarinic blockade by atropine (5 mg kg-1, i.v.) ...
A review. The low affinity A2B adenosine receptor, like any other adenosine receptor subtype, belongs to the super-family of seven transmembrane domain G protein-coupled receptors (7TMs GPCR) and is classified by the GPCR database in the family of rhodopsin like receptors (Class A of GPCR). It has been cloned from various species, including rat and human, and its sequences are highly similar across species, ranging from 85% identity between human and mouse and 95% identity between rat and mouse. The A2B receptors show a ubiquitous distribution, the highest levels are present in cecum, colon and bladder, followed by blood vessels, lung, eye and mast cells. Through A2B receptors adenosine seems to cause mast cells degranulation, vasodilation, cardiac fibroblast proliferation, inhibition of Tumor Necrosis Factor (TNF-α), increased synthesis of interleukin-6 (IL-6), stimulation of Cl- secretion in intestinal epithelia and hepatic glucose prodn. Hence, A2B adenosine receptor agonists could be useful ...
In the present study, we have made some progress in understanding the extracellular adenosine involved in the LFS-induced depotentiation at Schaffer collateral-CA1 synapses. There are four principal observations emerged from this work. First, the time-dependent reversal of LTP by LFS was mimicked by extracellular application of adenosine and was blocked by A1 adenosine receptor antagonist DPCPX but not by A2 receptor antagonist DMPX. Although transient extracellular application of 5-HT1A receptor agonist buspirone after LTP induction could also effectively reverse previously established LTP, 5-HT1A receptor antagonist NAN-190 did not affect the LFS-induced depotentiation. Second, the source of extracellular adenosine during LFS to exert depotentiation appeared to be attributable to the efflux of cAMP that is subsequently converted into adenosine by ecto-5′-nucleotidase. However, the extracellular conversion of ATP is not the major source of adenosine underlying the LFS-induced depotentiation. ...
We performed experiments to test the hypothesis that endogenous adenosine acts as an essential cofactor required for eliciting angiotensin II (Ang II)-induced afferent and/or efferent arteriolar vasoconstriction. Enalaprilat (2 mg IV) was administered to anesthetized rats to reduce endogenous Ang II levels. Kidneys and blood were harvested from these animals and used for study of renal microvascular function using the in vitro blood-perfused juxtamedullary nephron technique. Arteriolar inside diameter was monitored videomicroscopically in (1) normal kidneys, (2) kidneys subjected to adenosine receptor blockade (100 mumol/L 1,3-dipropyl-8-p-sulfophenylxanthine), and (3) kidneys continuously exposed to 1 mumol/L adenosine. Under resting conditions, arteriolar diameters were similar in all three groups of kidneys, averaging 24.8 +/- 1.0 microns (n = 23) in afferent arterioles and 24.0 +/- 0.9 microns (n = 16) in efferent arterioles. In normal kidneys, adenosine (10 mumol/L) decreased both afferent ...
The effect of (-)-N6-phenylisopropyl adenosine (PIA), a metabolically stable P1-receptor agonist, was investigated on guinea-pig isolated trachea. PIA showed two opposite effects: contraction, evident at low concentrations (10(-7) to 2-5 X 10(-6) M), and relaxation at higher doses. Relaxation by PIA was antagonized in an apparently competitive manner by two antagonists of extracellular (P1) adenosine receptors: theophylline (Theo) and 8-phenyltheophylline (PT). Contraction by PIA was not inhibited by methylxanthines and was not mediated by stimulation of cholinergic or histaminergic systems. Inhibitors of arachidonic acid cascade acting at different levels, i.e. indomethacin, nordihydroguaiaretic acid (NDGA) and BW755C, all inhibited the contraction by PIA, while they potentiated the relaxation in a concentration-dependent manner. Mepacrine, an inhibitor of phospholipase A2, inhibited the contraction by PIA, but did not affect the relaxation. These results indicate that the contractile effect induced by
Preeclampsia is a prevalent pregnancy hypertensive disease with both maternal and fetal morbidity and mortality. Emerging evidence indicates that global placental DNA hypomethylation is observed in patients with preeclampsia and is linked to altered gene expression and disease development. However, the molecular basis underlying placental epigenetic changes in preeclampsia remains unclear. Using 2 independent experimental models of preeclampsia, adenosine deaminase-deficient mice and a pathogenic autoantibody-induced mouse model of preeclampsia, we demonstrate that elevated placental adenosine not only induces hallmark features of preeclampsia but also causes placental DNA hypomethylation. The use of genetic approaches to express an adenosine deaminase minigene specifically in placentas, or adenosine deaminase enzyme replacement therapy, restored placental adenosine to normal levels, attenuated preeclampsia features, and abolished placental DNA hypomethylation in adenosine deaminase-deficient ...
Pharmacologic stress with dipyridamole has provided useful diagnostic, as well as prognostic, information in patients undergoing thallium-201 myocardial perfusion imaging. With its ultrashort half-life and a potent and consistent vasodilator effect, adenosine may be the coronary vasodilator of choice with myocardial perfusion imaging.. Fifty-one healthy subjects and 93 patients with suspected coronary artery disease constituted the study group. In this multicenter study the comparative safety and diagnostic efficacy of single-photon emission computed tomography (SPECT) thallium imaging during adenosine-induced coronary hyperemia was compared with exercise treadmill stress. There was a mean increase in heart rate of 37% and a mean decrease in diastolic blood pressure of 5% during the adenosine infusion of 140 μg/kg per min for 6 min. Adenosine infusion was well tolerated in 95% of the subjects. Side effects requiring intervention occurred in seven subjects (5%). None of the subjects experienced ...
Efflux transport of adenosine across the choroid plexus (CP) epithelium might contribute to the homeostasis of this neuromodulator in the extracellular fluids of the brain. The aim of this study was to explore adenosine transport across sheep CP epithelial cell monolayers in primary culture. To explore transport of adenosine across the CP epithelium, we have developed a method for primary culture of the sheep choroid plexus epithelial cells (CPEC) on plastic permeable supports and analysed [14C] adenosine transport across this cellular layer, [14C] adenosine metabolism inside the cells, and cellular uptake of [14C] adenosine from either of the chambers. The primary cell culture consisted of an enriched epithelial cell fraction from the sheep fourth ventricle CP and was grown on laminin-precoated filter inserts. CPEC grew as monolayers forming typical polygonal islands, reaching optical confluence on the third day after the seeding. Transepithelial electrical resistance increased over the time after
1. Human leucocytes whose adenine nucleotide pool was prelabelled with [3H]adenine were investigated for their capacity to release adenosine and its metabolites and histamine when activated with the calcium ionophore A23187, antiimmunoglobulin E and the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (f-MLP).. 2. Sixty-nine per cent of the 3H-label assimilated by the cells was incorporated into their adenine nucleotide pool in the ratio adenosine 5′-phosphate (AMP):adenosine 5′-pyrophosphate (ADP):adenosine 5′-triphosphate (ATP), 3:1:1. Spontaneous release of label from leucocytes plateaued at 5 min at 22.1 ± 4.2% of the total radiolabel incorporated and mainly consisted of hypoxanthine, inosine and adenosine.. 3. Activation of cells with the calcium ionophore A23187 (1.0 μmol/l) caused a net increase in [3H]purine release above baseline of 27.9 ± 4.6% accompanied by a net basophil histamine release of 46.6 ± 9.4%. A23187 (1.0-3.0 μmol/l) caused a parallel ...
A vasoconstrictory response to adenosine has been reported in coronary rings from fish. Since the reactivity of the large coronary arteries and the microcirculation may differ, the present study was undertaken to determine the role of adenosine in the intact coronary system of trout under constant pressure or flow using an isolated and non-working heart preparation. The involvement of nitric oxide (NO) and the interaction with noradrenaline were also studied. At 10(-9) to 10(-8 )mol l-1, adenosine caused a vasoconstrictory response, whereas between 10(-7) and 10(-5 )mol l-1 the response was predominantly vasodilative. Theophylline abolished both these responses to adenosine. The vasodilation induced by adenosine (at 10(-5 )mol l-1) was significantly reduced when the preparation was perfused under constant-flow than rather under constant-pressure conditions. The nitric oxide synthase inhibitor N-nitro-l-arginine (l-NA, 10(-4 )mol l-1) partially reduced the vasodilation induced by adenosine (at ...
Rat islets were used to compare the mechanisms whereby adenosine and adrenaline inhibit insulin release. Adenosine (1 microM-2.5 mM) and its analogue N6(-)-phenylisopropyladenosine (L-PIA) (1 nM-10 microM) caused a concentration-dependent but incomplete (45-60%) inhibition of glucose-stimulated release. L-PIA was more potent than D-PIA [the N6(+) analogue], but much less than adrenaline, which caused nearly complete inhibition (85% at 0.1 microM). 8-Phenyltheophylline prevented the inhibitory effect of L-PIA and 50 microM-adenosine, but not that of 500 microM-adenosine or of adrenaline. In contrast, yohimbine selectively prevented the inhibition by adrenaline. Adenosine and L-PIA thus appear to exert their effects by activating membrane A1 receptors, whereas adrenaline acts on alpha 2-adrenergic receptors. Adenosine, L-PIA and adrenaline slightly inhibited 45Ca2+ efflux, 86Rb+ efflux and 45Ca2+ influx in glucose-stimulated islets. The inhibition of insulin release by adenosine or L-PIA was ...
Adenosine was coupled to human serum albumin by two different procedures that preserved the purine and ribose rings. The conjugates were evaluated for antigenicity in rabbits and guinea pigs. A conjugate containing 2′(3′)-O-succinoyladenosine failed to elicit antibodies, whereas one containing laevulinic acid (O2′, 3′-adenosine-acetal) elicited antibodies in all animals injected. The affinity and specificity of binding of adenosine to three selected antisera were evaluated. Dissociation constants of 31-187 nM were observed. Displacement of adenosine binding to all antisera by adenine 5′-nucleotides, adenine, inosine and hypoxanthine required more than 1000-fold higher concentrations than of adenosine itself. Similar affinities for adenosine and 2′-deoxyadenosine were observed. By exploiting the high specificity of the antisera, a radioimmunoassay method was established that was capable of detecting down to 1 pmol of adenosine (20 nM) in unfractionated heart perfusates and cell ...
Adenosine is a multi-functional physiological molecule found abundantly in the body. It is one of the important components of ATP cellular energy metabolism. Adenosine has diverse actions as a ligand on many different types of cells and tissues acting via specific receptors. Currently, four subtypes of adenosine receptors are described, namely, the A1, A2A, A2B and A3 receptors. Neuroblastoma, mostly found in young children, is a malignant tumor derived from peripheral neurons in the body. Several different types of neuroblastoma cell lines of human origin have been established and contributed to the studies of neuroblastoma itself, neuronal differentiation, neurotransmitters, alcoholism, Alzheimers disease and other neuronal diseases and disorders. In 1987, it was shown by Abbracchio et al. that a human neuroblastoma cell line, IMR32, could be induced to differentiate into cells that have a more neuronal morphology, with long neurites, by an adenosine receptor agonist ...
August 20, 2007 By Grendel Burrell, M.D. [1] Preliminary results of the Phase 2, 50-patient, of BG9928 (ADENTRI®), an A1 adenosine receptor antagonist in stable patients with heart failure were reported in 2003 at the American Heart Associations annual scientific session. Dr. Barry Greenberg, professor of medicine and director of the Advanced Heart Failure Program at University of California, San Diego Medical Center, and colleagues reported the results in the August 14, 2007, issue of the Journal of the American College of Cardiology, in an article titled Effects of Multiple Oral Doses of an A1 Adenosine Antagonist, BG9928, in Patients With Heart Failure: Results of a Placebo-Controlled, Dose-Escalation Study (J Am Coll Cardiol, 2007; 50:600-606, doi:10.1016/j.jacc.2007.03.059 (Published online 29 July 2007)). BG9928 is a selective inhibitor of the A1 adenosine receptor. The objective of the study was to assess the pharmacokinetics and pharmacologic effects of BG9928 (ADENTRI®) in heart ...
Disclosed are processes for the synthesis of novel compounds that are A.sub.2B adenosine receptor antagonists, having the structure of Formula I or Formula II: ##STR00001## by cyclizing a compound of the formula (3): ##STR00002##
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The actions of adenosine on histamine release of human lung fragments were investigated. Histamine release was stimulated either with the calcium ionophore A 23187 orwith concanavalin A. Adenosine and its analogue 5-N-ethylcarboxamidoadenosine alone had no significant effect on basal release or on the release elicited by A 23187 or concanavalin A. However, in the presence of the adenosine receptor antagonist 8-[4-[[[[(2-aminoethyl)amino]-carbonyl] methyloxy]-phenyl]-1,3-dipropylaxanthine (XAC), which itself did not affect the release, adenosine increased the stimulated histamine release. On the other hand, in the presence of the nucleoside transport inhibitor S-(p-nitrobenzyl)-6-thioninosine (NBTI), adenosine caused a reduction in stimulated histamine release. NBTI itself caused a stimulation of release. Thus, a stimulatory effect of adenosine was seen in the presence ofXAC, whereas an inhibitory effect was unmasked by NBTI. From these data it is concluded that adenosine exerts two opposing ...
The actions of adenosine on histamine release of human lung fragments were investigated. Histamine release was stimulated either with the calcium ionophore A 23187 orwith concanavalin A. Adenosine and its analogue 5-N-ethylcarboxamidoadenosine alone had no significant effect on basal release or on the release elicited by A 23187 or concanavalin A. However, in the presence of the adenosine receptor antagonist 8-[4-[[[[(2-aminoethyl)amino]-carbonyl] methyloxy]-phenyl]-1,3-dipropylaxanthine (XAC), which itself did not affect the release, adenosine increased the stimulated histamine release. On the other hand, in the presence of the nucleoside transport inhibitor S-(p-nitrobenzyl)-6-thioninosine (NBTI), adenosine caused a reduction in stimulated histamine release. NBTI itself caused a stimulation of release. Thus, a stimulatory effect of adenosine was seen in the presence ofXAC, whereas an inhibitory effect was unmasked by NBTI. From these data it is concluded that adenosine exerts two opposing ...
TY - JOUR. T1 - A1 adenosine receptors potently regulate heart rate in mammalian embryos. AU - Hofman, Paul L.. AU - Hiatt, Kelly. AU - Yoder, Mervin. AU - Rivkees, Scott A.. PY - 1997. Y1 - 1997. N2 - A1 adenosine receptors (A1ARs) have been recently shown to be expressed in rodent embryonic hearts at very early stages of development. To determine the functional significance of fetal cardiac A1AR expression during embryogenesis, murine fetal heart preparations were studied between postconceptual days 9 and 12. Dose-response curves generated using a variety of adenosine agonists revealed that A1AR activation potently regulated fetal heart rates. The A1AR agonist, N6-cyclopentyladenosine, inhibited heart rates in a dose-dependent manner (half-maximal effective concentration = 3.6 x 10-8M) and stopped fetal cardiac contractions in 63% of preparations. In contrast, A2a and A2b receptor activation did not alter heart rates, and activation of A3 receptors produced modest declines in heart rates. ...
Title:Adenosine Receptors as Novel Targets for the Treatment of Various Cancers. VOLUME: 25 ISSUE: 26. Author(s):Bapi Gorain, Hira Choudhury*, Gan Sook Yee and Subrat Kumar Bhattamisra*. Affiliation:School of Pharmacy, Faculty of Health and Medical Science, Taylors University, Subang Jaya, Selangor, Department of Pharmaceutical Technology, School of Pharmacy, International Medical University, Bukit Jalil 57000, Kuala Lumpur, Department of Life Sciences, School of Pharmacy, International Medical University, Bukit Jalil 57000, Kuala Lumpur, Department of Life Sciences, School of Pharmacy, International Medical University, Bukit Jalil 57000, Kuala Lumpur. Keywords:Adenosine, adenosine receptors, receptor modulators, cancer, signalling pathways, tumour cell.. Abstract:Adenosine is a ubiquitous signaling nucleoside molecule, released from different cells within the body to act on vasculature and immunoescape. The physiological action on the proliferation of tumour cell has been reported by the ...
The ontogenesis of rat forebrain adenosine uptake sites labelled by [3H]nitrobenzylthioinosine ([3H]NBI) was determined and compared to that of rat forebrain adenosine receptors labelled by N6-cyclohexyl[3H]adenosine ([3H]-CHA). [3H]NBI binding is highly invariant with similar levels of [3H]NBI binding sites from embryonic day 19 to day 30 postpartum. Scatchard and Hill analyses reveal the binding of [3H]NBI in 6-day-old tissue to be indistinguishable from such binding in 30-day-old tissue. In contrast, [3H]-CHA binding is highly variant. [3H]CHA binding develops slowly but steadily from about embryonic day 19, with adult binding levels being achieved at around 25 days postpartum. The ontogenetic profile of [3H]CHA appears to coincide with synaptogenesis whereas that of [3H]NBI does not.
We prospectively recruited from 1230 consecutive patients undergoing CMRP. First pass CMRP was performed on a Philips Achieva CV 1.5 T MR scanner (Philips, The Netherlands), with standardised acquisition protocol with standard dose adenosine (SDA) at 140 µg/kg/min for 3 minutes. 3 short axis slices of 10 mm thickness were acquired per cardiac cycle using a single shot prospectively gated balanced TFE sequence (TR 2.5 ms, TE 1.3 ms, Flip angle 50° and voxel size 2.8 × 2.8 mm2) after the administration of a 0.1 mmol/Kg bolus of intravenous Gadolinium. Heart rate (HR) and blood pressure (BP) were recorded at baseline and during stress. Non responders were defined as those patients with a normal CMRP scan and blunted haemodynamic response (maximum HR increase ,10 beats per minute and fall in systolic BP (SBP) ,10 mmHg). CMRP in this group was then repeated with high dose adenosine (HDA) at 175 µg/kg/min for 3 minutes. CMRP images were interpreted by 2 independent experienced observers. Coronary ...
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TY - JOUR. T1 - Contribution of Adenosine A2A and A2B Receptors to Ischemic Coronary Dilation. T2 - Role of KV and KATP Channels. AU - Berwick, Zachary C.. AU - Payne, Gregory A.. AU - Lynch, Brandon. AU - Dick, Gregory M.. AU - Sturek, Michael. AU - Tune, Johnathan D.. PY - 2010/11/1. Y1 - 2010/11/1. N2 - This study was designed to elucidate the contribution of adenosine A2A and A2B receptors to coronary reactive hyperemia and downstream K+ channels involved. Coronary blood flow was measured in open-chest anesthetized dogs. Adenosine dose-dependently increased coronary flow from 0.72 ± 0.1 to 2.6 ± 0.5 mL/minute/g under control conditions. Inhibition of A2A receptors with SCH58261 (1 μm) attenuated adenosine-induced dilation by ~50%, while combined administration with the A2B receptor antagonist alloxazine (3 μm) produced no additional effect. SCH58261 significantly reduced reactive hyperemia in response to a transient 15 second occlusion; debt/repayment ratio decreased from 343 ± 63 to ...
Definition of adenosine diphosphate in the Financial Dictionary - by Free online English dictionary and encyclopedia. What is adenosine diphosphate? Meaning of adenosine diphosphate as a finance term. What does adenosine diphosphate mean in finance?
Adenosine is a purine nucleoside released locally in BAT when noradrenaline and ATP are released from sympathetic nerves. Recently it was found that adenosine activates murine and human brown adipocytes, and recruits beiging of white fat via adenosine A2A receptors (A2AR). Furthermore, studies with mice have shown improvements in glucose homeostasis after administration of A2AR agonists.. In this study the investigators use the PET radiotracer [15O]-H2O to quantify perfusion of BAT, white adipose tissue (WAT) and muscle in three conditions: room temperature, cold exposure and intravenous infusion of adenosine. Another PET radiotracer [11C]TMSX is used to quantify adenosine A2A receptor density of BAT, WAT and muscle in room temperature and during cold exposure. ...
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|p|3-Deazaneplanocin A (DZNep) hydrochloride is a selective inhibitor of ENZ2 inhibitor with IC50 value of 0.08-0.24 μM [1].|br /|ENZ2 is a sub-unit of PRC2 and plays an important role in regulating cell proliferation and cell-cycle progression. It has
View and buy high purity 3-Deazaneplanocin A hydrochloride from Tocris Bioscience. EZH2 histone methyltransferase inhibitor. Cited in 2 publications.
Although dipyridamole produces coronary vasodilation, most reports on dipyridamole effects in animals have failed to show a change in CBF after intravenous infusion of dipyridamole.16 17 18 19 To our knowledge, this is the first study to quantitatively estimate the change in CBF in response to intravenous dipyridamole in humans. We found CBF values for the dipyridamole stress to be lower than those at rest (Table 2⇑ and Figure 2⇑). Dipyridamole stress also caused a significant reduction in Paco2 (Table 1⇑), and the vascular response to Paco2 change caused by the dipyridamole infusion closely followed the response due to hypocapnia (Table 2⇑ and Figure 1⇑). Thus, the decrease in CBF during dipyridamole stress can be explained by the decrease in Paco2 rather than the direct action of dipyridamole on CBF. The decrease in Paco2 during dipyridamole stress is most likely due to the hyperventilation side effect of adenosine.29 It has been reported that large doses of intravenous adenosine and ...
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The role of adenosine and ATP in the regulation of hepatic arterial blood flow in the buffer response was studied in vitro and in a new in vivo model in the rabbit. The model achieves portal-systemic diversion by insertion of a silicone rubber prosthesis between the portal vein and inferior vena cava and avoids alterations in systemic haemodynamics. Hepatic arterial (HA) blood flow increased in response to reduced portal venous (PV) blood flow, the buffer response, from 19.4 (3.3) ml min-1 100 g-1 to 25.6 (4.3) ml min-1 100 g-1 (mean (SE), p | 0.05, Students paired t-test). This represented a buffering capacity of 18.7 (5.2) %. Intra-portal injections of ATP or adenosine (1 micrograms kg-1-0.5 mg kg-1) elicited immediate increases in HA blood flow to give -log ED50 values of 2.0 and 1.7 mg kg-1 for ATP and adenosine respectively. Injection of ATP and adenosine had no measurable effect on PV flow. In vitro, using an isolated dual-perfused rabbit liver preparation, the addition of 8
294964902 - EP 1019427 A1 2000-07-19 - N?6 -SUBSTITUTED-ADENOSINE-5 -URONAMIDES AS ADENOSINE RECEPTOR MODULATORS - [origin: WO9906053A1] A series of adenosine-5 -uronamide derivatives bearing N 6 -arylurea, alkarylurea, heteroarylurea, arylcarbonyl, alkarylcarbonyl or heteroarylcarbonyl groups which have affinity and, in some cases, selectivity for the adenosine A1 or A3 receptors are disclosed. These compounds can be used in a pharmaceutical composition to treat disorders caused by excessive activation of the A1 or A3 receptors, or can be used in a diagnostic application to determine the relative binding of other compounds to the A1 or A3 receptors.[origin: WO9906053A1] A series of adenosine-5 -uronamide derivatives bearing N 6 -arylurea, alkarylurea, heteroarylurea, arylcarbonyl, alkarylcarbonyl or heteroarylcarbonyl groups which have affinity and, in some cases, selectivity for the adenosine A1 or A3 receptors are disclosed. These compounds can be used in a pharmaceutical composition to treat
Symptoms of Adenosine triphosphatase deficiency, anaemia due to including 12 medical symptoms and signs of Adenosine triphosphatase deficiency, anaemia due to, alternative diagnoses, misdiagnosis, and correct diagnosis for Adenosine triphosphatase deficiency, anaemia due to signs or Adenosine triphosphatase deficiency, anaemia due to symptoms.
Yang Z, Sun W, Hu K (Apr 2012). "Molecular mechanism underlying adenosine receptor-mediated mitochondrial targeting of protein ... Yang Z, Sun W, Hu K (Apr 2012). "Molecular mechanism underlying adenosine receptor-mediated mitochondrial targeting of protein ... adenosine; hypoxia and Akt-induced stem cell factor; ROS generated via pharmacologic activation of the mitochondrial potassium- ...
Adenosine triphosphate is a major "energy currency" of the cell. The high energy bonds between the phosphate groups can be ... ISBN 978-3-642-33430-6. Agteresch, Hendrik J.; Dagnelie, Pieter C.; van den Berg, J Willem; Wilson, J H. (1999). "Adenosine ...
Nave CR (2005). "Adenosine Triphosphate". Hyper Physics [serial on the Internet]. Georgia State University. Douglass JG, Patel ... Regrelor was synthesized from adenosine diphosphate (ADP), an endogenous chemical involved in metabolism. The authors noted ...
"ATP: Adenosine Triphosphate , Boundless Biology". courses.lumenlearning.com-US. Retrieved 2017-11-12. Carvalho AT, Szeler K, ... For example, dATP stands for deoxyribose adenosine triphosphate. NTPs are the building blocks of RNA, and dNTPs are the ...
Kielley WW (1961). "Myosin adenosine triphosphatase". In Boyer PD, Lardy H, Myrbäck K (eds.). The Enzymes. 5 (2nd ed.). New ... Martin SS, Senior AE (November 1980). "Membrane adenosine triphosphatase activities in rat pancreas". Biochimica et Biophysica ... ATPases (EC 3.6.1.3, adenylpyrophosphatase, ATP monophosphatase, triphosphatase, SV40 T-antigen, adenosine 5'-triphosphatase, ... to form a molecule of adenosine triphosphate (ATP). This enzyme works when a proton moves down the concentration gradient, ...
When caffeine is consumed, it antagonizes adenosine receptors; in other words, caffeine prevents adenosine from activating the ... an agent that reduces the effects of adenosine). The caffeine molecule is structurally similar to adenosine, and is capable of ... a receptor complex composed of 1 adenosine A1 receptor and 1 adenosine A2A receptor) in the axon terminal of glutamate neurons ... The affinity (KD) values of caffeine for the human adenosine receptors are 12 μM at A1, 2.4 μM at A2A, 13 μM at A2B, and 80 μM ...
hENT4 is uniquely selective for adenosine, and also transports a variety of organic cations. The generalized transport reaction ... Noji T, Karasawa A, Kusaka H (Jul 2004). "Adenosine uptake inhibitors". European Journal of Pharmacology. 495 (1): 1-16. doi: ... They are blocked by adenosine reuptake inhibitors like dipyridamole and dilazep, drugs used clinically for their vasodilatory ... By regulating the concentration of adenosine available to cell surface receptors, mammalian ENTs additionally influence ...
Adenosine receptors are thought to be a large driver of drowsiness and sleep, and their action increases with extended ... Caffeine is an adenosine receptor antagonist, and only indirectly increases catecholamine transmission in the brain. Pitolisant ... Caffeine has been found to increase striatal dopamine in animal models, as well as inhibit the inhibitory effect of adenosine ... Kamiya T, Saitoh O, Yoshioka K, Nakata H (June 2003). "Oligomerization of adenosine A2A and dopamine D2 receptors in living ...
The product is adenosine diphosphate (ADP) and an inorganic phosphate (Pi). ADP can be further hydrolyzed to give energy, ... "ATP: Adenosine Triphosphate". cnx.org. Retrieved 2018-05-16. Wackerhage, H.; Hoffmann, U.; Essfeld, D.; Leyk, D.; Mueller, K.; ... adenosine monophosphate (AMP), and another inorganic phosphate (Pi). ATP hydrolysis is the final link between the energy ... catabolic reaction process by which chemical energy that has been stored in the high-energy phosphoanhydride bonds in adenosine ...
... 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 ... These two ... "Adenosine-cannabinoid receptor interactions. Implications for striatal function". Br. J. Pharmacol. 160 (3): 443-453. doi: ... can be differentiated by their output connectivity and their expression of dopamine and adenosine receptors and neuropeptides. ...
Other names in common use include ADP ribose phosphorylase, and adenosine diphosphoribose phosphorylase. Evans WR, San Pietro A ... Stern AI, Avron M (1966). "An adenosine 5'-diphosphate ribose:orthophosphate adenylyltransferase from Euglena gracilis". ... 1966). "Phosphorolysis of adenosine diphosphoribose". Arch. Biochem. Biophys. 113 (1): 236-44. doi:10.1016/0003-9861(66)90178-0 ...
Adenosine is very relevant in bone metabolism, as it plays a role in formation and activation of both osteoclasts and ... Adenosine acts by binding to purinergic receptors and influencing adenylyl cyclase activity and the formation of cAMP and PKA ... Then, it converts adenosine triphosphate into cyclic AMP, which activates Protein kinase A. PKA leads to protein tyrosine ... There are two main types of purinergic receptors, P1 binding to adenosine, and P2 binding to ATP or ADP, presenting different ...
... and express the peptide enkephalin and a high density of dopamine D2 and adenosine A2A receptors (they also express adenosine ... In contrast, the D2-type medium spiny neurons in the NAcc shell which express adenosine A2A receptors have no role in ... Ferré S, Lluís C, Justinova Z, Quiroz C, Orru M, Navarro G, Canela EI, Franco R, Goldberg SR (June 2010). "Adenosine- ... The indirect pathway (i.e., D2-type) neurons in the NAcc core which co-express adenosine A2A receptors activation-dependently ...
This pathway consists of MSNs that express dopamine receptor D2, muscarinic acetylcholine receptor M1, and adenosine receptor ... and adenosine receptor A1. The direct pathway has been proposed to facilitate motor actions, timing of motor actions, gating of ... "Adenosine-cannabinoid receptor interactions. Implications for striatal function". British Journal of Pharmacology. 160 (3): 443 ...
Kline LK, Fittler F, Hall RH (1969). "N6-(Δ2-isopentenyl)adenosine. Biosynthesis in transfer ribonucleic acid in vitro". ...
PPi is pyrophosphate APS is adenosine 5-phosphosulfate; ATP is adenosine triphosphate; O2 is oxygen molecule; AMP is adenosine ... This incorporation releases pyrophosphate (PPi). ATP sulfurylase converts PPi to ATP in the presence of adenosine 5´ ... and with the substrates adenosine 5´ phosphosulfate (APS) and luciferin. The addition of one of the four deoxynucleotide ...
... increased adenosine receptor function; increased cortisol. In the central nervous system (CNS), the major mediators of the ...
The nucleoside, adenosine, is then deaminated and hydrolyzed to form hypoxanthine via adenosine deaminase and nucleosidase ... "Adenosine deaminase (ADA) deficiency". Learn.Genetics. Archived from the original on 3 November 2014. Retrieved 31 October 2014 ... IMP is then converted to AMP (adenosine monophosphate) using GTP and aspartate, which is converted into fumarate. While IMP can ... Adenylate kinase is a specific nucleoside-monophosphate kinase that functions only on adenosine-monophosphate. Carbohydrate ...
Ghosh HP, Preiss J (1966). "Adenosine diphosphate glucose pyrophosphorylase. A regulatory enzyme in the biosynthesis of starch ... I. Purification and properties of the adenosine diphosphoglucose pyrophosphorylase of Arthrobacter species NRRL B1973". J. Biol ... Other names in common use include ADP glucose pyrophosphorylase, glucose 1-phosphate adenylyltransferase, adenosine diphosphate ... glucose pyrophosphorylase, adenosine diphosphoglucose pyrophosphorylase, ADP-glucose pyrophosphorylase, ADP-glucose synthase, ...
... and express the peptide enkephalin and a high density of dopamine D2 and adenosine A2A receptors (they also express adenosine ... adenosine A1 receptors, dynorphin peptides, and substance P peptides. Indirect pathway MSNs inhibit their output structure and ... and express the peptides dynorphin and substance P and dopamine D1 and adenosine A1 but not A2A receptors (Ferréet al., 1997; ... "Adenosine-cannabinoid receptor interactions. Implications for striatal function". Br. J. Pharmacol. 160 (3): 443-453. doi: ...
Histidine biosynthesis is carefully regulated by feedback inhibition/ R5P can be converted to adenosine diphosphate ribose, ... Evans WR, San Pietro A (January 1966). "Phosphorolysis of adenosine diphosphoribose". Archives of Biochemistry and Biophysics. ... Adenosine triphosphate). Formation of each molecule is controlled by the flow of glucose 6-phosphate (G6P) in two different ...
Adenosine activates adenosine receptors. The word purine (pure urine) was coined by the German chemist Emil Fischer in 1884. He ... adenosine, guanosine). These nucleotides are two of the building blocks of DNA and RNA respectively. The purine bases also play ... and adenosine monophosphate (AMP). In order to perform these essential cellular processes, both purines and pyrimidines are ...
APC Adenosine deaminase deficiency, partial; 102700; ADA Adenosine triphosphate, elevated, of erythrocytes; 102900; PKLR ...
July 2008). "Brain adenosine A2A receptor occupancy by a novel A1/A2A receptor antagonist, ASP5854, in rhesus monkeys: ... SCH-442,416 is a highly selective adenosine A2a subtype receptor antagonist. It is widely used in its 11C radiolabelled form to ... April 2005). "In vivo imaging of adenosine A2A receptors in rat and primate brain using [11C]SCH442416". European Journal of ... El Yacoubi M, Costentin J, Vaugeois JM (December 2003). "Adenosine A2A receptors and depression". Neurology. 61 (11 Suppl 6): ...
... adenosine triphosphate, the energy molecule; and oxygen. It occurs in modified excretory organs known as Malpighian tubules in ...
Dowler MJ, Nakada HI (1968). "Yeast phosphoramidate-adenosine diphosphate phosphotransferase". J. Biol. Chem. 243 (7): 1434-40 ... Other names in common use include phosphoramidate-adenosine diphosphate phosphotransferase, and phosphoramidate-ADP- ...
"Fluorescent Ligands for Adenosine Receptors". Bioorg. Med. Chem. Lett. 23 (1): 26-36. doi:10.1016/j.bmcl.2012.10.112. PMC ...
doi:10.1016/S0031-9422(00)89846-5. Vignais, Pierre V.; Vignais, Paulette M.; Defaye, Genevieve (2002). "Adenosine diphosphate ...
Adenosine and sleep-wake regulation. Prog Neurobiol. 2004 Aug;73(6):379-96. Shenton ME, Kikinis R, Jolesz FA, et al. ... Additionally, he has studied the buildup of adenosine in the basal forebrain following sleep deprivation. In the area of ...
Adenosine also antagonizes chronotropic and ionotropic effects of circulating catecholamines. Overall, adenosine decreases the ... Adenosine's effects are concentration-dependent. Adenosine's receptors are competitively antagonized by methylxanthines such as ... Mader TJ, Gibson P (August 1997). "Adenosine receptor antagonism in refractory asystolic cardiac arrest: results of a human ... Daly JW, Jacobson KA, Ukena D (1987). "Adenosine receptors: development of selective agonists and antagonists". Progress in ...
A1 adenosine receptor[edit]. Main article: Adenosine A1 receptor. The adenosine A1 receptor has been found to be ubiquitous ... "Entrez Gene: ADORA2A adenosine A2A receptor".. *^ a b Jacobson KA, Gao ZG (2006). "Adenosine receptors as therapeutic targets" ... A2A adenosine receptor[edit]. Main article: Adenosine A2A receptor. As with the A1, the A2A receptors are believed to play a ... The adenosine receptors (or P1 receptors[1]) are a class of purinergic G protein-coupled receptors with adenosine as the ...
Adenosine diphosphate (ADP), also known as adenosine pyrophosphate (APP), is an important organic compound in metabolism and is ... ADP in the blood is converted to adenosine by the action of ecto-ADPases, inhibiting further platelet activation via adenosine ... ADP can be interconverted to adenosine triphosphate (ATP) and adenosine monophosphate (AMP). ATP contains one more phosphate ... The diphosphate group of ADP is attachted to the 5 carbon of the sugar backbone, while the adenosine attaches to the 1 carbon ...
... is a adenosines (CHEBI:22260) adenosine (CHEBI:16335) is a purines D-ribonucleoside (CHEBI:142355) ... adenosine (CHEBI:16335). 2-thio-N6-(Δ2-isopentenyl)adenosine (CHEBI:73551) has functional parent adenosine (CHEBI:16335). 3-O- ... adenosine (CHEBI:16335). L-adenosylselenohomocysteine (CHEBI:77028) has functional parent adenosine (CHEBI:16335). adenosine ... N6,N6-dimethyladenosine (CHEBI:28284) has functional parent adenosine (CHEBI:16335). N6-(Δ2-isopentenyl)adenosine (CHEBI:62881 ...
Adenosine A1 receptors (A1Rs) have been shown to be involved in antinociception in preclinical models for several decades. Thus ... Keil GJ, DeLander GE (1994) Adenosine kinase and adenosine deaminase inhibition modulate spinal adenosine- and opioid agonist- ... Sawynok J. (2013) Adenosine and Pain. In: Masino S., Boison D. (eds) Adenosine. Springer, New York, NY. * First Online 23 July ... Adenosine Antinociception Analgesia Adenosine kinase inhibitors Ectonucleotidases Acupuncture Caffeine Spinal cord This is a ...
... 2007 Schools Wikipedia Selection. Related subjects: Chemical compounds. Adenosine 5-triphosphate. ... adenosine and other nucleosides (ADO , AMP , ADP , ATP). P1 receptors have A1, A2a, A2b, and A3 subtypes (A as a remnant of ... Adenosine 5-triphosphate (ATP), discovered in 1929 by Karl Lohmann, is a multifunctional nucleotide primarily known in ... adenosine - itself composed of an adenine ring and a ribose sugar - and three phosphate groups (triphosphate). The phosphoryl ...
The adenosine deaminase test may be used to help determine whether a person has a Mycobacterium tuberculosis infection (TB) of ... Adenosine deaminase (ADA) is a protein produced by cells throughout the body and is associated with the activation of ... The adenosine deaminase (ADA) test is not a diagnostic test, but it may be used along with other tests such as pleural fluid ... Adenosine deaminase (ADA) is a protein that is produced by cells throughout the body and is associated with the activation of ...
Adenosine is also available without a brand name, ie as the generic medicine. Adenosine is a natural body chemical that is used ... Adenocor injection contains the active ingredient adenosine, which is a type of medicine called an anti-arrhythmic. ... Adenosine is also available without a brand name, ie as the generic medicine. Adenosine is a natural body chemical that is used ... Adenosine is also available without a brand name, ie as the generic medicine. Adenosine is a natural body chemical that is used ...
N6-(dimethylallyl)adenosine 5-diphosphate (CHEBI:71678) is a adenosine 5-phosphate (CHEBI:37096). N6-(dimethylallyl)adenosine ... adenosine 5-monophosphate (CHEBI:16027) is a adenosine 5-phosphate (CHEBI:37096). adenosine thiamine triphosphate (CHEBI: ... adenosine 5-(hexahydrogen pentaphosphate) (CHEBI:40096) is a adenosine 5-phosphate (CHEBI:37096). adenosine 5-(hexanoyl ... adenosine 5-(pentahydrogen tetraphosphate) (CHEBI:18334) is a adenosine 5-phosphate (CHEBI:37096). adenosine 5- ...
Adenosine deaminase (ADA) deficiency is an inherited disorder that damages the immune system and causes severe combined ... New insights into adenosine-receptor-mediated immunosuppression and the role of adenosine in causing the immunodeficiency ... Adenosine deaminase deficiency is caused by mutations in the ADA gene. This gene provides instructions for producing the enzyme ... Adenosine deaminase deficiency is very rare and is estimated to occur in approximately 1 in 200,000 to 1,000,000 newborns ...
Media in category "Adenosine triphosphatases". The following 74 files are in this category, out of 74 total. ... Retrieved from "https://commons.wikimedia.org/w/index.php?title=Category:Adenosine_triphosphatases&oldid=131322728" ...
Other articles where Adenosine triphosphatase is discussed: cell: The sodium-potassium pump: An enzyme called sodium-potassium- ... adenosine triphosphate (ATP)Adenosine triphosphate, or ATP, is the primary carrier of energy in cells. The water-mediated ... ": { "url": "/science/adenosine-triphosphatase", "shareUrl": "https://www.britannica.com/science/adenosine-triphosphatase", " ...
Using adenosine to help unmask dormant pulmonary vein conduction following ablation, researchers reduced atrial tachyarrhythmia ... The Adenosine Following Pulmonary Vein Isolation to Target Dormant Conduction Elimination (ADVICE) trial was presented here at ... Adenosine may be used during the AF ablation procedure to detect pulmonary veins at risk of later reconnection, the so-called ... "If a routine strategy of adenosine testing is used with elimination of dormant conduction when present, which it is in about ...
Adenosine-induced transient cardiac arrest may serve as an alternative. Methods.All... ... Adenosine Aneurysm Cardiac arrest Carotid artery Basilar artery This is a preview of subscription content, log in to check ... Adenosine-induced transient asystole for management of a basilar artery aneurysm. Case report. J Neurosurg. 1999;91:687-90. ... Adenosine-induced transient cardiac arrest may serve as an alternative.. Methods. All patients who underwent microsurgical ...
... a selective A2A adenosine-receptor agonist, for resting stress-myocardial perfusion scans. ... Adenosine versus regadenoson comparative evaluation in myocardial perfusion imaging: Results of the ADVANCE phase 3 multicenter ... adenosine injection (Adenoscan), according to the announcement. Lexiscan is administered as a non-weight-adjusted rapid bolus, ... which, published reports observe, is a less complicated regimen than what is required for adenosine; its also expected to have ...
The adenosine deaminase (ADA) test is not a diagnostic test, but it may be used along with other tests such as pleural fluid ... Adenosine deaminase (ADA) is a protein that is produced by cells throughout the body and is associated with the activation of ... If adenosine deaminase (ADA) is markedly elevated in pleural fluid in a person with signs and symptoms that suggest ... 2010 October). Adenosine Deaminase Levels in CSF of Tuberculous Meningitis Patients. J Clin Med Res. 2010 October; 2(5): 220- ...
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When adenosine enters the circulation, it is broken down by adenosine deaminase, which is present in red blood cells and the ... Adenosine is believed to be an anti-inflammatory agent at the A2A receptor. Topical treatment of adenosine to foot wounds in ... Adenosine used as a second messenger can be the result of de novo purine biosynthesis via adenosine monophosphate (AMP), though ... Adenosine has been shown to promote thickening of hair on people with thinning hair. A 2013 study compared topical adenosine ...
Learn more about Adenosine uses, effectiveness, possible side effects, interactions, dosage, user ratings and products that ... Adenosine comes in three different forms: adenosine, adenosine monophosphate (AMP), and adenosine triphosphate (ATP).. ... Adenosine Phosphate, Adenosine 5-Triphosphate Disodium, Adenosine; Adenosine Monophosphate (AMP), Adénosine Monophosphate (AMP ... Methylxanthines interacts with ADENOSINE. Methylxanthines might block the affects of adenosine. Adenosine is often used by ...
The scientists discovered a new way to stimulate brown fat and thus burn energy from food: The bodys own adenosine activates ... adenosine. Adenosine is typically released during stress. Crucial for transmitting the adenosine signal is the adenosine ... Adenosine activates brown adipose tissue. "If adenosine binds to this receptor in brown fat cells, fat burning is significantly ... "Browning" of white fat by adenosine In addition, the research team investigated the possibility that adenosine transforms white ...
The first and only journal dedicated to publishing the rapidly advancing field of caffeine and adenosine signaling research, ... physiology and pharmacology of adenosine signaling; from the physiological role of adenosine in neuromodulation, inflammation ... Journal of Caffeine and Adenosine Research (formerly Journal of Caffeine Research: The International Multidisciplinary Journal ... In addition, the Journal holds special interest in caffeine, the adenosine receptor antagonist that constitutes the most ...
We also discuss the treatment opportunities, potential limitations and biomarker-based strategies related to adenosine-targeted ... Signalling induced by extracellular adenosine (eADO) can suppress antitumour immunity through multiple mechanisms. Herein, the ... with inhibitors of extracellular adenosine (eADO) signalling constituting an expanding class of agents. Induced by tissue ... Adenosine interaction with adenosine receptor A2a promotes gastric cancer metastasis by enhancing PI3K-AKT-mTOR signaling. Mol ...
Intracellular adenosine is rapidly metabolized either via phosphorylation to adenosine monophosphate by adenosine kinase, or ... Adenosine (UNII: K72T3FS567) (Adenosine - UNII:K72T3FS567). Adenosine. 3 mg in 1 mL. ... Adenosine Injection, USP is supplied as a sterile solution in normal saline as follows: NDC. Adenosine Injection, USP (3 mg per ... larger doses of adenosine may be required or adenosine may not be effective. Adenosine effects are potentiated by dipyridamole ...
Adenosine is a ubiquitous signaling molecule whose physiological functions are mediated by its interaction with four G-protein- ... Thus, full characterisation of the role of adenosine in tumor development, by addressing the question of whether adenosine ... Adenosine receptors and cancer Biochim Biophys Acta. 2011 May;1808(5):1400-12. doi: 10.1016/j.bbamem.2010.09.020. Epub 2010 Oct ... Although all adenosine receptors now have an increasing number of recognised biological roles in tumors, it seems that the A(2A ...
Intracellular adenosine is rapidly metabolized either via phosphorylation to adenosine monophosphate by adenosine kinase, or ... ADENOSINE (UNII: K72T3FS567) (adenosine - UNII:K72T3FS567). ADENOSINE. 3 mg in 1 mL. ... larger doses of adenosine may be required or adenosine may not be effective. Adenosine effects are potentiated by dipyridamole ... Since adenosine kinase has a lower Km and Vmax than adenosine deaminase, deamination plays a significant role only when ...
adenosine may be diluted to 1 mg/mL as follows:. 0.33 mL of adenosine solution (3 mg/mL). plus. 0.67 mL of 0.9% NaCl. = ... adenosine is rapidly metabolized by adenosine deaminase in whole blood and by endothelial cells to inosine; its in vitro half ... adenosine may cause first, second or third degree heart block; because of adenosines very short half life, these effects are ... theophylline, caffeine) antagonize the actions of adenosine; larger doses of adenosine may be required or it may not be ...
Adenosine monophosphate (AMP), also known as 5-adenylic acid, is a nucleotide. AMP consists of a phosphate group, the sugar ... "Adenosine monophosphate". The Human Metabolome Database. Retrieved 3 July 2020. Maiuolo J, Oppedisano F, Gratteri S, Muscoli C ... In a catabolic pathway, adenosine monophosphate can be converted to uric acid, which is excreted from the body in mammals. The ... Krishan S, Richardson DR, Sahni S (March 2015). "Adenosine monophosphate-activated kinase and its key role in catabolism: ...
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How is adenosine deaminase severe combined immunodeficiency (ADA-SCID) treated?. *What are treatments for adenosine deaminase ... What causes adenosine deaminase severe combined immunodeficiency (ADA-SCID)?. ANSWER This is a serious disease that happens ... How do you take care of yourself or your child with adenosine deaminase severe combined immunodeficiency (ADA-SCID)? ... What do you need to know about adenosine deaminase severe combined immunodeficiency (ADA-SCID)? ...
An international team of researchers have designed and built a model biological supercomputer powered by adenosine triphosphate ... An international team of researchers have designed and built a model biological supercomputer powered by adenosine triphosphate ...

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