INHIBITION OF THE MIGRATING MOTOR COMPLEX BY DUODENAL DRAINAGE IN MAN

The effect of varying bile acid output on fasting small intestinal mot ility was investigated in healthy male volunteers. Biliary output was manipulated by jejunal infusion of isotonic mannitol, which resulted i n increased output, and by prolonged drainage of duodenal contents, wh ich resulted in decreased output. Intestinal motility was measured by manometric recordings performed at four levels in the proximal small i ntestine. A marker dilution technique was used to measure pancreatico- biliary output. There were three experimental groups: duodenal drainag e, nondrainage and control. Both duodenal drainage and nondrainage gro ups underwent jejunal saline infusion, followed by mannitol infusion. The control group did not receive drainage or infusions. In the draina ge group, 0.41 (0.13-0.68) activity fronts of the migrating motor comp lex (MMC) per hour were recorded during saline infusion, but only 0.06 (0-0.19) activity fronts per hour were observed during mannitol infus ion. In the nondrainage group, 0.71 (0.61-0.81) activity fronts per ho ur were observed during saline infusion and 0.50 (0.18-0.82) activity fronts per hour were recorded during mannitol infusion. In the control group, 0.58 (0.33-0.84) activity fronts per hour were recorded during the first 4-h session and 0.58 (0.45-0.71) activity fronts per hour d uring the second session. There was no difference between the number o f activity fronts per hour observed in the control group and those obs erved in the saline infusion of the drainage group. In contrast, there was a significant decrease in the number of activity fronts per hour in the drainage group during mannitol infusion, compared to both non-d rainage group during mannitol infusion (P < 0.01) and controls (P < 0. 05). In conclusion, decreased biliary output caused by duodenal draina ge in combination with mannitol infusion is associated with inhibition of the cyclic activity of MMC in the proximal small intestine in man.