GUANETHIDINE‐INDUCED VASODILATATION IN THE RABBIT, MEDIATED BY ENDOGENOUS HISTAMINE

Abstract

The effects of guanethidine (0.5–4 mg/kg i.v.) on arterial pressure, hindlimb blood flow and hindlimb vascular resistance (HVR) were studied in unanaesthetized rabbits subjected to ‘total’ autonomic block. Evidence that this response was mediated by histamine release was that (a) 3H‐labelled histamine levels in the hindlimb venous blood rose substantially after guanethidine; (b) infusion of exogenous histamine caused an inhibition of the guanethidine‐induced vasodilatation; and (c) competitive antagonism of the response was obtained with the H2‐antagonist burimamide. There was good correlation between the [3H]‐histamine release and the time course of the vasodilator response. Glyceryl trinit..