Characteristic motor activity of the gastrointestinal tract in fasted conscious dogs measured by implanted force transducers.

Gastrointestinal contractile actiivity from the gastric body to the terminal ileum in conscious dogs was continuously recorded for several weeks by means of chronically implanted strain-gage force transducers. It was found that the 24-hr changes in the gastrointestinal contractile activity consisted of the two different major patterns, the digestive and interdigestive patterns. In the interdigestive state, a cyclic, recurring, caudad-moving band of strong contractions starting in the stomach and the duodenum and traversing the entire length of the small intestine was observed. When one band of strong contractions reached the distal ileum, another developed in the stomach and the duodenum again and propagated in a caudad direction. Such recycling episodes interrupted by long-lasting quiescence repeatedly occurred until the next meal. These characteristic contractile activities observed in our dogs are identical with the interdigestive myoelectric complex of the stomach and the small bowel recently reported by Code and Marlett (5). Four sequential phases (I-IV) of the migrating myoelectric complex, defined in terms of action potential activity, seem to correspond to the resting (quiescence), preceding irregular contractions, strong contractions, and subsiding contractions observed in the present study, respectively. Function and control mechanism of the interdigestive contractile activity were discussed.