Contractile activity of vasotocin, oxytocin, and vasopressin on mammalian prostate.

The neurohypophyseal peptides arginine vasotocin, oxytocin and arginine vasopressin contracted guinea pig, rat, canine and human prostates with potencies and efficacies that were comparable to those of noradrenaline and methacholine. All three neuropeptides raised prostatic tone and elicited contractions at 10(-9) or 10(-8) M, with an order of efficacy: arginine vasotocin greater than oxytocin greater than arginine vasopressin. The findings suggest a physiological role for these peptides in prostatic smooth muscle contraction and possibly also in other aspects of male reproductive function.