Rapid frequency rhythmic postprandial motility in the canine ileum

We report here a novel motor phenomenon that we recorded from the canine terminal ileum in the postprandial period. In chronic models that allowed us to monitor myoelectrical activity and intraluminal pressure from the jejunum and distal ileum, we regularly saw in the ileum, but not in the jejunum, a rhythmic sequence of intraluminal pressure waves at a frequency of 19-24 cycles/min. This unusual motor pattern was rarely seen in the first 2 h after food and was essentially absent during fasting; it appeared reproducibly 1-4 h after food, at the time when chyme reached the ileum. The phenomenon was accompanied by spike bursts that were usually at the same rapid, rhythmic frequency, but the rate of the ileal slow wave persisted at the preprandial level (13-15/min). These findings further exemplify differences in the regulation of the motility between jejunum and ileum; moreover, the phenomenon highlights the capacity of the distal small intestine to response specifically to the nature of its luminal contents. This reaction of the ileum to the arrival of dietary residues is deserving of further study in the evaluation of the small bowel's response to a meal.