Effects of losartan on vasoconstrictor responses to angiotensin II in the forearm vascular bed of healthy volunteers

Abstract

Losartan, intra-arterially administered, causes no effect on baseline vascular resistance, but markedly inhibits Ang-II-induced vasoconstriction in the human forearm vascular bed. Relatively high doses of intra-arterial losartan were required when compared to the antagonism by the orally administered drug. These data indicate that Ang-II-induced vasoconstriction is mediated by AT1-receptors, which are blocked by losartan. The more effective antagonism exerted by oral losartan is presumably explained by the formation of Exp3174. Endogenous Ang II does not contribute to baseline vascular tone in healthy, sodium-replete, subjects.