Modulation of norepinephrine-induced vasoconstriction by endothelin-1 and nitric oxide in rat tail artery.

The effects of endothelin-1 (ET-1) and an inhibitor of the synthesis of nitric oxide (NO) have been examined on vasoconstrictor responses to nerve stimulation and norepinephrine in the rat isolated perfused tail artery. In endothelium-denuded preparations, a 60-min exposure to 0.3 nM ET-1 had no effect on the basal perfusion pressure, but significantly enhanced responses to stimulation (1 Hz, 10 s) and norepinephrine (10 ng) to 124±9% (n=6) and 139±14% (n=8), respectively, of control responses