Contractile responses of human deferential artery and vas deferens to vasopressin

We studied the effects of vasopressin on isolated rings of human deferential artery and vas deferens (prostatic portion) obtained from patients undergoing radical cystectomy (n = 11) or prostatectomy (n = 10). Ring segments of artery or vas deferens were studied in organ bath experiments at optimal resting tension. In artery rings, vasopressin produced concentration-dependent, endothelium-independent contractions with an EC50 of 4.5 x 10(-10) M. The presence of NG-nitro-L-arginine methyl ester hydrochloride (10(-4) M), an inhibitor of nitric oxide synthase, did not change significantly (P > 0.05) the vasopressin-induced contraction. In ring preparations of the prostatic part of the vas deferens, vasopressin induced phasic contractions with an EC50 of 7.0 x 10(-9) M. The vasopressin V1 receptor antagonist, d(CH2)5Tyr(Me)AVP (10(-8) and 10(-6)), displaced to the right in parallel the control curve to vasopressin in artery and vas deferens rings. These results indicate that vasopressin exerts a powerful constrictor action on human deferential artery and vas deferens by direct stimulation of V1 receptors. It is concluded that the deferential artery may dampen the passage of blood to the vas deferens in circumstances characterized by increased plasma vasopressin levels.