Multiple neurokinin receptors in the rat lower urinary tract.

Multiple neurokinin receptors which mediate motor effects and plasma extravasation were found in the rat lower urinary tract. In the bladder and urethra, exogenous neurokinins closely mimicked the effects of capsaicin, consistent with the hypothesis that neurokinins released form sensory nerves modulate vesicourethral function. In the ureters, neurokinins and capsaicin produced similar effects on plasma extravasation but opposite effects on motility, suggesting that the visceromotor effect of endogenous neurokinins may be prevented by the inhibitory action of other substances (i.e. CGRP) co-stored in capsaicin-sensitive sensory nerves.