EFFECTS OF VASOACTIVE-INTESTINAL-PEPTIDE, PEPTIDE HISTIDINE METHIONINE, AND NEUROPEPTIDE-Y ON INTRACAVERNOUS PRESSURE IN THE RABBIT

In anesthesized white rabbits blood was extracorporeally circulated from the left carotid artery into the penile corporeal bodies with a constant flow rate. Corpus cavernosum pressure (CCP) responses to intracavernous injections of drugs were recorded in animals with aortic nonocclusion and aortic occlusion, respectively. Vasoactive intestinal polypeptide (VIP, 1 mug, 5 mug, and 20 mug) dissolved in 0.5 mL volumes, induced no significant increases in CCP compared with equivalent volumes of solvent, but the peptide increased the time interval until return of CCP to steady state level. Peptide histidine methionine induced a significant increase in the maximal CCP obtained in nonocclusion and the time interval until return of CCP to steady state levels was increased in both aortic nonocclusion and occlusion. Neuropeptide Y produced an increase in the maximal CCP in animals with aortic occlusion, and a minor increase in the time interval until return of CCP values to steady state levels in both aortic nonocclusion and occlusion. Thus, all the peptides tested were capable of influencing the smooth muscle tissues involved in penile outflow regulation.