Effects of Bradykinin on Forearm Venous Tone and Vascular Resistance in Man

Abstract

The effects of intravenous injections of synthetic bradykinin on the vascular dynamics of the forearm were studied in nine normal subjects. A plethysmographic technique was used to measure forearm blood flow and to estimate forearm venous tone. Bradykinin decreased mean systemic arterial pressure, elevated forearm blood flow, and reduced calculated forearm vascular resistance and also venous tone. The venodilatation was preceded by brief venoconstriction which was prevented in five subjects pretreated with the antiadrenergic agent, guanethidine. It is postulated (a) that this venoconstriction is one of the compensatory reflex actions that accompany reduction of systemic arterial pressure, and (b) that the prime effect of bradykinin on both the arterial and the venous beds of the forearm is a direct vasodilatation.