Effect of serotonin on gastrointestinal electrical activity in the conscious piglet.

In conscious piglets with electrodes implanted in the wall of the antrum pylori, duodenum, jejunum and ileum, the influence of intravenous infusion of serotonin (5-HT), 4 micrograms/kg/min for 2 hours, on gastrointestinal electrical activity and arterial pressure was examined. 5-HT was without significant influence on antral electrical activity and arterial pressure. In the small intestinal parts 5-HT provoked a shortening of the interval of the migrating myoelectrical complex (MMC) by reducing the duration of phase I and phase II activities, and an increase in propagation velocity. 5-HT also induced an increase in phase III activity. A possible involvement of 5-HT in the initiation and propagation of the MMC is suggested.