Potentiation of the effects of noradrenaline and of sympathetic stimulation of the perfused rat caudal artery by angiotensin

Abstract

The isolated perfused caudal artery of the rat develops tachyphyllaxis rapidly to the direct constrictor action of angiotensin but not towards the potentiation of responses to submaximally effective periarterial stimulation or to noradrenaline. These potentiations persist in the presence of maximally effective concentrations of cocaine, are unaffected by increased sodium concentration and are enhanced by raised concentrations of calcium. Thus, angiotensin potentiates the effects of sympathetic nervous activity by an influence on the role of calcium in the contractile process. Hydrochlorothiazide did not affect arterial tone, the responses of the artery, or the potentiation to noradrenaline caused by angiotensin.