Facilitation of cardiac sympathetic function by angiotensin II: role of presynaptic angiotensin receptors.

Intravenous infusion of two separate doses of angiotensin II in pentobarbital-anesthetized, desipramine-treated animals produced dose-related increases in arterial blood pressure and caused significant potentiation of the cardioacceleration observed during the stimulation of the right postganglionic cardiac sympathetic nerve fibers. Positive chronotropic effects of intravenous norepinephrine were not altered during angiotensin II infusion. Prior administration of Saralasin, an angiotensin receptor antagonist, caused significant attenuation of the pressor action of angiotensin II, and also significantly antagonized the facilitatory effect of angiotensin II on sympathetic transmission to the myocardium. These results suggest that angiotensin II can cause facilitation of sympathetic nerve function to the myocardium via an action on angiotensin receptors which may be located on sympathetic nerve terminals.