Effect of motilin on the sphincter of Oddi in the dog.

To investigate the action of motilin on the sphincter of Oddi, the flow rate of the perfusate (FRP) discharged into the duodenal lumen through the orifice of the common bile duct was measured by means of an electric drop counter in decerebrated dogs. Motilin in doses above 0.5 micrograms/kg i.v. reduced or stopped the FRP. The fifty percent recovery time of FRP was 20 min and full recovery time was 30 min. The reduction of FRP induced by motilin was unaffected by denervation and atropinization. These results suggest that motilin caused an increase in tone of the sphincter of Oddi by acting on the sphincter muscle.