MOTOR RESPONSE OF THE HUMAN ISOLATED SMALL-INTESTINE AND URINARY-BLADDER TO PORCINE NEUROMEDIN U-8

Porcine neuromedin U-8 produced a concentration (0.3 nM-1 μM)-dependent contraction of the longitudinal muscle of the human isolated ileum, which was unaffected by either atropine (1 μM) or tetrodotoxin (1 μM). By contrast, neuromedin U-8 had only a weak effect on the circular muscle of the human isolated ileum. Neuromedin U-8 also produced a concentration-dependent contraction of mucosa-free muscle strips from the dome of the human isolated urinary bladder, its action being unaffected by either atropine or tetrodotoxin. These findings indicate that neuromedin U-8 exerts a direct contractile effect on smooth muscle of the human intestinal and urinary tract.