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 remains unknown. In this study, we assessed the effect of a liquid meal on proximal and distal colonic motor activity. In 12 healthy volunteers, colonic 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 the 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 value; P = 0.2). The intrabag volume of the barostat was significantly more 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 immediate tonic contraction that is less pronounced than in the distal colon.