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Am J Physiol Heart Circ Physiol 239: H365-H370, 1980;
0363-6135/80 $5.00
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AJP - Heart and Circulatory Physiology, Vol 239, Issue 3 365-H370, Copyright © 1980 by American Physiological Society

ARTICLES

Inhibition by adenosine of catecholamine-induced increase in rat atrial contractility

J. B. Rockoff and J. G. Dobson Jr

Because adenosine has been shown to attenuate the catecholamine-induced increase in myocardial cAMP formation and glycogen phosphorylase activity (Circ. Res. 43: 785-792, 1978), the present study was undertaken to determine whether the nucleoside inhibits the catecholamine-elicited increase in cardiac contractile state. Isolated rat atria were bathed in oxygenated physiologic saline and stimulated to contract isometrically at 2/s. Isoproterenol (0.1 microM) increased peak contractile force (PCF) by 96% and the rate of force development (+dF/dt) by 107%. Adenosine (10 microM) alone had no effect on these contractile parameters. Isoproterenol in the presence of adenosine increased PCF and +dF/dt only 15 and 14%, respectively. Elevation of bathing medium Ca2+ or administration of dibutyryl cAMP (DBcAMP) increased PCF and +dF/dt, but these responses were not decreased by adenosine. Inosine, adenine, adenosine 5'-monophosphate, and guanosine inhibited the isoproterenol-induced responses 5-22%. The results indicate that adenosine markedly inhibits, whereas some related purines only mildly attenuate, the catecholamine-elicited, but not the Ca2+- or DBcAMP-elicited, increases in contractility. Thus, adenosine may antagonize catecholamine-elicited glycogenolysis and enhanced contractile state in the heart by exerting an effect at the level of, or proximal to, cAMP formation.


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K. Miyazaki, S. Komatsu, M. Ikebe, R. A. Fenton, and J. G. Dobson Jr.
Protein kinase C{epsilon} and the antiadrenergic action of adenosine in rat ventricular myocytes
Am J Physiol Heart Circ Physiol, October 1, 2004; 287(4): H1721 - H1729.
[Abstract] [Full Text] [PDF]


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