Variations in plasma motilin, somatostatin, and pancreatic polypeptide concentrations and the interdigestive myoelectric complex in dog

We have looked at the plasma concentrations of motilin, pancreatic polypeptide (PP), and somatostatin (STS) during the various phases of the interdigestive motor complex (IDMC) in dogs. As expected, motilin cyclical increase was always associated with the phase III of the IDMC. Statistical analysis of PP variations revealed a significant rise 10 min before duodenal phase III; however, in individual animals, this relationship was inconsistent. Although a dose-related increase in PP blood levels was induced by administration of synthetic canine motilin (0–200 ng kg−1 iv), fasting plasma levels of PP were not correlated with the concentrations of circulating endogenous motilin. After truncal vagotomy, while motilin release and the intestinal motility pattern remained unaltered, the phase III associated cyclical increases of PP disappeared. Infusion of physiological amounts of PP (1 μg kg−1 h−1 for 3 h) mimicking the postprandial release failed to reproduce a fed pattern type of intestinal motility and of mot...