Gastrointestinal Motor Patterns: Motilin as a Coordinating Factor

Our aim was to further define the role of neural and hormonal control of upper gastrointestinal motility patterns. In five dogs, the stomach and duodenum were separated enterically by transecting and oversewing the proximal duodenum and by anastomosing a Roux-en-Y jejunal limb to the pylorus. Five intact dogs served as controls. After recovery, motility was recorded on four or more occasions during fasting and after feeding. Plasma was sampled for motilin radioimmunoassay. In three Roux-en-Y dogs, motilin (0.1 μk/kg iv) was administered. We found in the Roux-en-Y group that the characteristic MMC occurred in the stomach, duodenum, and jejunal limb, but the jejunal MMC had a much shorter period (P < 0.005). Gastric and duodenal MMCs were coordinated temporally and were associated with peaks in plasma motilin concentration. Jejunal MMCs had no apparent association with plasma motilin. Feeding disrupted the gastric and duodenal MMC and decreased plasma motilin, but inhibited the jejunal MMC in only 6 of 12 experiments. Exogenous motilin induced a "premature" MMC in the stomach, duodenum, and jejunum. This study suggests that (1) enteric neural continuity and/or luminal continuity are not necessary for coordination of gastric and duodenal motor patterns, and (2) post-prandial inhibition of the duodenal MMC may not depend on the presence of ingested nutrient in the duodenum. Hormonal factors, possibly motilin, may play a role in initiation and coordination of gastric and duodenal motor patterns.