Diurnal changes in colonic motor profile in conscious dogs.

Continuous strain gauge recordings of ileal and proximal colonic motility were performed in 5 dogs fitted with a cannula in the ileum. The 22-hr records obtained with a normal ileocolonic transit were repeated during external deviation of digesta and after vagotomy. In the fasted state, the motility of the proximal colon was characterized by phases of contractions occurring at 25-min mean intervals modulated by the occurrence of migrating motor complexes on the ileum. Food intake induced three consecutive changes in colonic motility: a supplementary phase of activity immediately after the meal, an inhibition during the second postprandial hour, and a period of increased frequency of the phases of activity lasting 8-10 hr. The fasted motor profile of the proximal colon reappeared at the end of the postprandial disruption of the ileal cyclic activity. External deviation of ileal content abolished the late colonic response to the meal. Vagotomy did not modify any diurnal variation.