GUANETHIDINE-INDUCED VASODILATATION IN RABBIT, MEDIATED BY ENDOGENOUS HISTAMINE

Abstract

1 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 unanesthetized rabbits subjected to "total" autonomic block. 2 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. 3 There was good correlation between the [3H]-histamine ;elease and the time course of the vasodilator response. Glyceryl t..