Voluntary suppression of defecation delays gastric emptying

We wished to test the hypothesis that colonic loading with fecal material leads to delayed gastric emptying. Twelve healthy male volunteers were studied. Each of these subjects went through two randomized study periods of four days. In one of these, the subjects defecated upon urge, in the other period defecation was voluntarily suppressed. Gastric emptying of a semisolid meal (mashed potatoes) was measured with the noninvasive applied potential tomography technique. On day 3 no significant changes in gastric emptying were found, but on day 4 the emptying rate had decreased from 85.8 +/- 11.0%/hr (mean +/- SEM) to 70.3 +/- 10.9%/hr (P < 0.05) and the T50 had increased from 38.5 +/- 3.4 min to 46.2 +/- 4.0 min (P < 0.025). The duration of the lag phase (4.1 +/- 1.5 min) was not significantly altered by suppression of defecation. Our conclusion is that voluntary suppression of defecation delays gastric emptying in normal subjects. This "cologastric brake" may be involved in the pathogenesis of upper abdominal symptoms in constipated patients.