[Endorphin control of blood motilin and the gastrointestinal motor complex in the dog].

To evaluate the role of endogenous opiates in the regulation of plasma motilin and the interdigestive motor complex of the small bowel, naloxone was administered in dogs. During the infusion of the opiate antagonist, the frequency of motilin cyclic release and of the motor complex was decreased. Moreover, with naloxone, peak increases in plasma motilin were similar to those measured during the control period in 5 of the 8 experiments. They were lower in 3 occasions. These results suggest that endogenous opiates do not play an essential role in the basal organization of intestinal interdigestive motility but that they are able to modify the frequency and the amplitude of motilin cyclic release. They support the possibility that endogenous opiates could, in some circumstances, exert a significant influence on the motor activity of the small intestine.