Effect of rectal distension on gallbladder emptying and circulating gut hormones

Abnormalities of upper gut motility, including a delay of gastric emptying and small bowel transit, found in patients with constipation may be secondary to factors originating in the colon or rectum as a result of faecal stasis. The aim was to determine if stimulation of mechanosensory function by rectal distension affects postprandial gallbladder emptying and release of gastrointestinal peptides participating in control of upper gut motility.

Eight healthy volunteers were studied with an electronic barostat and a plastic bag positioned in the rectum. Intrabag pressure was maintained at minimal distension pressure + 2 mmHg on one occasion and on a pressure that induced a sensation of urge on the other. Gallbladder volume and plasma concentrations of cholecystokinin (CCK), pancreatic polypeptide (PP) and peptide YY (PYY) were measured before and after ingestion of a 450-kcal mixed liquid meal.

Rectal distension enhanced maximum gallbladder emptying from 66 +/- 7% to 78 +/- 5% (P < 0.05). Distension tended to increase integrated plasma PYY from 77 +/- 30 pM min to 128 +/- 40 pM min in the first hour after the meal (P = 0.08) and it suppressed integrated plasma PP from 1133 +/- 248 pM min to 269 +/- 284 pM min in the second hour (P < 0.05). Integrated plasma CCK concentrations were not significantly affected.

Mechanosensory stimulation of the rectum enhances postprandial gallbladder emptying and influences postprandial release of gut hormones involved in the regulation of gastrointestinal motility in healthy subjects. These mechanisms may play a role in the pathogenesis of the upper gastrointestinal motor abnormalities observed in constipated patients.