TONIC AND PHASIC MOTOR-ACTIVITY IN THE PROXIMAL AND DISTAL COLON OF HEALTHY HUMANS

In healthy humans, meals stimulate phasic and tonic motor activity in the unprepared distal colon. The response of the proximal colon remain s unknown. In this study, we assessed the effect of a liquid meal on p roximal and distal colonic motor activity. In 12 healthy volunteers, c olonic tone and phasic motility were simultaneously recorded by using an electronic barostat and perfused catheters in the fasting state and in response to a 1,000-kcal meal. The meal significantly increased th e phasic activity in the distal colon (230 +/- 46% of the basal value; P = 0.02) but not in the proximal colon (138 +/- 25% of the basal val ue; P = 0.2). The intrabag volume of the barostat was significantly mo re reduced in the distal than in the proximal colon (74 +/- 11 vs. 50 +/- 9% of the basal values, respectively; P = 0.04). We conclude that the postprandial response of the unprepared proximal colon is an immed iate tonic contraction that is less pronounced than in the distal colo n.