THE HUMAN DEFERENTIAL ARTERY - ENDOTHELIUM-MEDIATED CONTRACTION IN RESPONSE TO ADRENERGIC-STIMULATION

The human vas deferens receives its blood supply from the deferential artery, a long vessel which usually arises from the superior vesical a rtery. To date no information is available on the responsiveness of th is artery to adrenergic stimulation. In the present work the effects o f electrical field stimulation and noradrenaline were studied isometri cally in rings of human deferential artery obtained from patients unde rgoing radical cystectomy (n = 7) or prostatectomy (n = 10). Electrica l field stimulation (1-8 Hz, 20 V, 0.25 ms for 30 s) caused frequency- dependent contractions that were abolished by guanethidine, tetrodotox in or prazosin. Noradrenaline (10(-7)-10(-4) M) induced concentration- dependent contractions with an EC(50) of 1.3 X 10(-5) M. The increases in tension induced by electrical field stimulation and noradrenaline were of greater magnitude in arteries denuded of endothelium. The inhi bitor of nitric oxide synthesis, NG-nitro-L-arginine methyl ester (10( -4) M), potentiated the responses to electrical field stimulation and noradrenaline in artery rings with endothelium. The results indicate t hat the human deferential artery has a marked ability to contract in r esponse to adrenergic stimulation; they also suggest that the endothel ium may have an inhibitory effect on adrenergic responses due, at leas t in part, to the release of endothelial nitric oxide. These effects c ould play an important role in regulating blood flow to the vas defere ns.