Origin of migrating myoelectric complex in sheep.

The electrical activity of the gastroduodenal junction was recorded in conscious sheep for 8 to 12 wk with chronically implanted electrodes. The flow of digesta was simultaneously recorded, and the duodenal bulb was isolated at the time of implantation. The mean slow-wave frequency of the antrum was 5.6 +/- 0.3/min with spike bursts randomly superimposed on about 60% of the slow waves. The activity of the duodenal bulb was characterized by an absence of slow-wave unpropagated spike bursts and by two types of propagated spike bursts. The first consisted of isolated bursts accompanied by a rapid movement of digesta through the entire duodenum and proximal jejunum. The second, an irregular series of 8-12 spike bursts was associated with total evacuation of the duodenal bulb, followed in turn by an inhibition of antral spiking activity and the development of a migrating myoelectric complex (MMC) in the distal duodenum. The results indicate that in sheep organization of the MMC is located at the duodenal level where the duodenal bulb has a reservoir function.