Effect of bombesin, bradykinin, substance P and CGRP in prostate, bladder body and neck.

Lower urinary tract tissues respond heterogeneously to adrenergic and cholinergic agents. However, the action of bioactive peptides on these tissues has not been extensively studied. The contractile and relaxant effects of nine peptides-bradykinin, cholecystokinin, vasoactive intestinal polypeptide, gastrin, substance P, bombesin, neuropeptide Y, calcitonin gene-related peptide, and motilin-have been compared in the rat bladder body, bladder neck, and left ventral prostate in vitro. All three tissues contracted to bombesin and to bradykinin, although the bladder neck was less sensitive to the contractile effects of bradykinin than the other two tissues. Substance P only contracted the bladder body. Of all the peptides tested, relaxation was only observed to calcitonin gene-related peptide, which relaxed the bladder neck and prostate (phenylephrine-contracted) but not the bladder body (carbamylcholine-contracted). Thus lower urinary tract tissues are responsive to certain bioactive peptides in a nonhomogeneous fashion. These studies raise the possibility that selective modulation of peptide function may be an approach to therapy of urogenital disorders.