Motor activity of the upper gastrointestinal tract undergoes a cyclic pattern during fasting called the migrating motor complex (MMC). The role of the duodenum in controlling this cyclic activity was studied in the dog. Five dogs served as controls. In four other dogs, the entire duodenum and the proximal 20 cm of jejunum were resected. The ostia of the bile duct and pancreatic duct were preserved as "mucosal buttons" and reimplanted in situ into the jejunum after gastrojejunostomy. All dogs had manometry catheters placed into the stomach and serosal electrodes implanted onto the small intestine to monitor gastrointestinal motility. All control dogs showed the characteristic MMC in the stomach and small intestine, the period being 112 ± 16 min (mean ± SEM). After total duodenectomy, an irregular, noncyclic pattern of contractions occurred in the stomach in two of the four dogs during fasting. The other two dogs had a cyclic pattern of gastric motility; however, the overall characteristics of these cyclic patterns of gastric motility differed from that of controls. A variable proportion of the phases of cyclic gastric activity did not fit the criterion for temporal coordination with the jejunum as defined from study of control dogs. In contrast, jejunal motility in all four dogs after total duodenectomy continued to exhibit the characteristic MMC, but the period of the cycle (58 ± 7 min) was shorter than in controls (P < 0.05). "Ectopic" jejunal activity fronts with no preceding gastric contractions were frequent. After total duodenectomy, plasma concentration of motilin remained lower than normal and showed no cyclic variation with the jejunal MMC. After total duodenectomy, feeding interrupted the fasting motor pattern of the stomach as in controls, but did not disrupt the MMC in the jejunum. We concluded that the duodenum has an important role in initiating cyclic gastric motor activity and in coordinating motor activity between the stomach and the small intestine.
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