Influence of angiotensin II on the α-adrenoceptors involved in mediating the response to sympathetic nerve stimulation in the rabbit isolated distal saphenous artery

Abstract

Under normal experimental conditions, sympathetic nerve-mediated responses to electrical field stimulation in the isolated distal saphenous artery of the rabbit are sensitive to prazosin (0.1 μM) and so, by definition, are mediated by α1-adrenoceptors. In the presence of angiotensin II (A II, 0.05 μM) however, a component of the response to nerve stimulation became resistant to prazosin. This 'uncovered' response was virtually abolished by the selective α2-adrenoceptor antagonist rauwolscine (1 μM), a concentration that in the absence of A II had enhanced nerve-mediated responses. Exposure to A II therefore, allows the clear demonstration of a role for postjunctional α2-adrenoceptors in mediating the contractile response to sympathetic nerve stimulation in this arterial preparation.