The nitric oxide synthase inhibitor L-NMMA potentiates noradrenaline-induced vasoconstriction: effects of the alpha2-receptor antagonist yohimbine

Abstract

These data demonstrate, that in humans in vivo, endogenous NO attenuates noradrenergic constriction. The effects of YO suggest that endothelial alpha2-adrenoceptors are involved in the release of NO and other vasodilating substances. Furthermore, there is an additive NO-independent vasodilation, which can be unmasked by L-NMMA.