Modulation of human upper gastrointestinal motility by rectal distension

The effects of rectal distension on upper gastrointestinal motility were investigated in six healthy subjects. On a control day, gastric and duodenal motor activity was recorded for nine hours of fasting and for four hours after a meal, duodeno-caecal transit being assessed in both interdigestive and digestive states. Motor activity and transit were also measured on a test day during which the rectum was distended for one hour during fasting and for one hour postprandially. Control and test days were randomised. During fasting, rectal distension increased the incidence of migrating motor complexes (0.8 +/- 0.3 v 0.5 +/- 0.2 h; p less than 0.01) and reduced the duodenal phase 2 motility index to 66 +/- 45% of that observed on the control day (p less than 0.01). Further, duodeno-caecal transit time was increased by rectal distension (99 +/- 30 v 71 +/- 35 min; p less than 0.05). Postprandially, the period of rectal distension was marked by a reduction in the duodenal motility index to 24 +/- 13% of that observed during the comparable period on the control day (p less than 0.001) and a concomitant increase in duodeno-caecal transit time (113 +/- 22 v 80 +/- 17 min; p less than 0.01). We conclude that upper gastrointestinal motor activity, the effector of luminal transit, may be profoundly influenced by stimulation of distal afferents.