The opening of ATP-sensitive K+ (K+ATP) channels contributes to the mechanism of metabolic coronary vasodilation. The aim of the present study was to determine whether K+ATP channel opener pinacidil augments coronary vasodilation induced by beta-adrenoceptor stimulation. In anesthetized dogs, coronary vasodilation in response to intracoronary infusion of a beta 1-adrenoceptor agonist denopamine, selective beta 2-adrenoceptor stimulation with isoproterenol after bisoprolol or nitroglycerin was studied before and during simultaneous intracoronary infusion of pinacidil at a dose of 1 microgram/min, which had no effect on basal hemodynamics. Pinacidil augmented the denopamine-induced increase in coronary blood flow (CBF) from 38 +/- 9 to 66 +/- 16% (P < 0.05) but did not affect the denopamine-induced by isoproterenol or nitroglycerin. Thus pinacidil selectively augmented beta 1-adrenoceptor-mediated coronary vasodilation. These observations suggest that the K+ATP channel opener pinacidil may increase myocardial perfusion during metabolic stress associated with beta 1-adrenoceptor stimulation.
Effects of Y-26763, an active metabolite of a new K-channel opener Y-27152, on renal function in anesthetized dogs
