Effects of Quinidine on Venous Responses to Adrenergic and Nonadrenergic Constrictor Stimuli: Indirect Evidence of Two Sites of Action in Vascular Smooth Muscle 1

Abstract

Summary

The effect of quinidine on adrenergic and nonadrenergic constrictor stimuli was studied in the perfused canine saphenous vein. Quinidine significantly reduced constrictor responses to sympathetic nerve stimulation, phenylephrine and norepinephrine while responses to a nonadrenergic constrictor drug, 5-hydroxytryptamine, were not reduced, indicating that quinidine interferes with stimuli that activate alpha adrenergic receptors. Quinidine also had a smaller yet significant effect on constrictor response to KCl suggesting a possible second site of action.