ATP-sensitive K+ channel opener pinacidil augments beta 1-adrenoceptor-induced coronary vasodilation in dogs.

Y Katsuda, K Egashira, H Ueno, Y Arai, Y Akatsuka, T Kuga, H Shimokawa, A Takeshita

Index: Am. J. Physiol. 270(6 Pt 2) , H2210-5, (1996)

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Abstract

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.