Multiple effects of cholecystokinin admi- nistrated during various phases of the migrating myoelectic complex upon the small intestinal interdigestive and digestive motility in sheep

SUMMARY There is no detailed data regarding the effect of cholecystokinin on the migrating myoelectric complex (MMC) in sheep. Thus, in five rams seven bipolar platinum electrodes were implanted to the abomasal antrum and entire small intestine. The strain gauge force transducer was also attached near the duodenal electrode in four of these animals. In the course of chronic experiments, the myoelectric and motor activities were continuously recorded in fasted and non-fasted sheep. During control recordings, at least two normal consecutive phases 3 of the MMC were recorded. Then, slow injections of cholecystokinin-octapeptide (CCK-OP) of 0.02, 0.2 and 2.0 microgramms per kg of body weight were given intravenously during phase 1, 2a or 2b of the MMC, identified in the duodenum, and next two consecutive phases 3 of the MMC were recorded. The moderate dose of CCK-OP administered during phase 2a in non-fasted rams shortened the MMC cycles significantly while the highest dose of the hormone increased the MMC cycle duration and inhibited phase 3 of the MMC in the duodenum. No such effect was observed in the jejunum. However, duration of phase 3 of the MMC in this region was shortened principally by the highest dose of CCK-OP. First phase 3 of the MMC arriving after the highest CCK dose was not entirely organized. It is concluded that CCK may inhibit the MMC pattern in ovine small bowel and its effect in the duodenum is the most evident. However, this effect seems to be the consequence of pharmacological rather than physiological action of CCK. Thus, CCK does not appear to play as important role in the control of the small-intestinal MMC in sheep as in monogastric animals.