Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.3.5 (5'-nucleotidase)
 3,167 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The electrophysiological effect of 5'-adenosine monophosphate (AMP) was examined in isolated atrial myocytes of guinea pig. Membrane potential and ionic currents were measured by the tight-seal, whole-cell patch-clamp technique. AMP caused the shortening of atrial action potential in a dose-dependent manner. In voltage-clamp experiments, AMP (3-10 microM) caused the activation of IKACh as well as the decrease in basal ICa. Prolongation of action potential duration caused by isoproterenol (20 nM) was antagonized by AMP (10 microM). Isoproterenol (20 nM) occasionally caused the sustained rhythmic activity and the subsequent application of AMP (10 microM) terminated it. AOPCP (10 microM), which inhibits 5'-nucleotidase and hence prevents breakdown of AMP, did not significantly attenuate the effect of AMP on shortening action potential. However, the application of adenosine deaminase (1 U/ml), which deaminates adenosine to inosine, partially reversed the shortening of action potential caused by AMP (10 microM). These results indicate that (1) AMP could activate IKACh and decrease basal ICa simultaneously, and antagonize the isoproterenol-stimulated action potential prolongation; and (2) the observed electrophysiological effect of AMP in whole-cell preparation is attributed to AMP per se as well as its degradative product, adenosine.
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PMID:Evidence of direct activation of adenosine A1 receptor by 5'-adenosine monophosphate in isolated guinea pig atrial myocytes. 162 79

We measured adenosine release into venous plasma as an index of interstitial adenosine concentration during free flow exercise hyperemia. Isolated, blood-perfused dog calf muscles were stimulated at 6 Hz for 10 min at free flow. Plasma samples were collected before, during, and after the exercise period for analysis of plasma adenosine concentration [( ADO]) by HPLC. Adenosine release (Rado) was calculated as plasma flow times venous-arterial [ADO] difference. Rado (nmole/min/100 g) went from -0.1 +/- 0.1 at rest to 6.6 +/- 4.6 during 6-Hz exercise. Isoproterenol infusion, which caused an increase in blood flow equivalent to 6-Hz exercise, did not result in increased Rado. Infusion of the 5'-nucleotidase inhibitor, alpha, beta, methylene adenosine 5'-diphosphate (AOPCP) did not prevent the increase in Rado during exercise. These results support the hypothesis that interstitial adenosine concentration increases during sustained free flow twitch exercise and that this results in increased release of adenosine into venous plasma.
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PMID:Adenosine release into venous plasma during free flow exercise. 381 46

The effect of isoproterenol perfusion on cAMP levels and phosphorylase activity was investigated in the spontaneously hypertensive rat (SHR) and Kyoto Wistar normotensive control rat (WKY) heart. The basal force of contraction in physiological salt solution perfused hearts was comparable between SHR and WKY. However, the force of contraction in response to 10 nM isoproterenol perfusion was decreased approximately 20-30% in SHR heart as compared to WKY heart. Basal cAMP levels were reduced in SHR hearts as compared to WKY hearts. Isoproterenol perfusion resulted in an increase in cAMP levels over the basal cAMP values which was 50% and 100% in SHR and WKY hearts, respectively. Basal phosphorylase activity was higher in SHR hearts as compared to WKY hearts. However, the percentage increase in phosphorylase activity by isoproterenol perfusion over the basal values was approximately 400% in WKY hearts and only 200% in SHR hearts. The ouabain-sensitive (Na+, K+)-ATPase activity, Ca2+ binding in the absence of ATP, sialic acid content, and 5'-nucleotidase activity of purified cardiac plasma membranes was not altered in SHR as compared to WKY. These results would suggest beta-adrenergic mediated adenylate cyclase stimulation is decreased in SHR myocardium while other plasma membrane properties and associated enzymes may not be altered.
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PMID:Reduced cAMP levels and glycogen phosphorylase activation in isoproterenol perfused SHR myocardium. 631 20