ENDOTHELIAL NITRIC-OXIDE ATTENUATES VASOCONSTRICTOR RESPONSES TO NERVE-STIMULATION AND NORADRENALINE IN THE RAT TAIL ARTERY

The effects of the nitric oxide synthesis inhibitor, N(G)-nitro-L-arginine (NOLA), have been examined in perfused segments of rat tail artery. NOLA (1 and 10-mu-M) significantly enhanced the vasoconstrictor responses to perivascular nerve stimulation (5 Hz, 10 s) and noradrenaline (10 ng). The enhancing effects of NOLA were prevented by L-arginine, but not by D-arginine, and were absent in endothelium-denuded artery segments. The results suggest that nitric oxide derived from endothelial cells attenuates vasoconstrictor responses to both nerve stimulation and noradrenaline.