Motor responses to food of the ileum, proximal colon, and distal colon of healthy humans

Intraluminal pressures and motility indexes were recorded from ileum, ascending colon, rectosigmoid colon, and rectum of 6 healthy men. Three different test meals were eaten at 5-hour intervals. During fasting, migrating motor complexes were identified in the ileum. In ascending colon, irregular, isolated peaks of pressure were common; when bursts of continuous activity occurred, their predominant frequency was 6/min. Regular contractile activity occurred in distal colon at a frequency of 2.5-3.5/min, although 3 subjects also demonstrated rates of 7/min. There were both synchronous and independent contractions of the rectosigmoid and rectum, and no temporal relationship was obvious between motor activities of ascending and distal colons. When the preprandial hour contained no migrating motor complex, all meals increased the ileal motility index by 50%. The motility index of ascending and rectosigmoid colons were enhanced by solid meals, but not by meals containing amino acids. We conclude that motor patterns in the colon vary regionally, both fasting and after food. Results obtained at one site of the large intestine should not be extrapolated to others.