Vasoactive intestinal polypeptide (VIP) in the male genitourinary tract: concentration and motor effect.

Vasoactive intestinal polypeptide (VIP) has previously been shown in nerves of the male and female genitourinary tract, appearing to innervate vascular and nonvascular smooth and epithelial cells. In the present study the concentration of VIP in tissue extracts of different parts of the male genitourinary tract from cat and man was determined by radioimmunoassay. In addition, the effect of VIP on the contractility of the smooth muscle from the cat genitourinary tract was investigated in vitro. The tissue concentrations of VIP were generally higher in cat than in man. In both species high concentrations were found in the vas deferens, bladder, urethra and prostate, In concentration from 3 x 10(-8) to 6 x 10(-7) mol x 1-1, VIP inhibited in a concentration-dependent manner the muscle contractions in specimens from all regions examined, i.e., the vas deferens, ureter, corpus of the bladder, and urethra. The data indicate that VIP might play a physiologic role in the local nervous control of the smooth muscle activity in the male genitourinary tract.