CHOLINERGIC PATHWAYS IN THE EFFECT OF MOTILIN ON THE CANINE ILEUM ANDGALLBLADDER MOTILITY - IN-VIVO AND IN-VITRO EXPERIMENTS

1. Motilin (10 nM to 1 mu M) had no effect on the spontaneous contract ions but increased in a dose-dependent manner the amplitude of the ele ctrically induced cholinergically mediated contractions of muscle stri ps isolated from canine ileum and gallbladder, and the effect was sign ificant. 2. Motilin (5 to 20 ng/kg)injected intravenously in conscious dogs dose-dependently increased the ileum and gallbladder pressure, S imilar was the effect of CCK8 (10 to 40 ng/kg i.v. for the ileum and 1 to 10 ng/kg i.v. for gallbladder). 3. The motilin or CCK8-induced inc rease in ileum and gallbladder pressure was prevented by atropine (10 to 50 mu g/kg i.v.) or hexamethonium (0.5 to 3 mg/kg i.v.). 4. Somatos tatin (0.5 and 2 mu g/kg i.v.) also prevented the motilin-induced incr ease in ileum and gallbladder pressure.