Dose-related effects of cerulein short infusions on proximal small bowel motility in sheep

The effect of cholecystokinin (CCK) upon the intestinal motility has not been entirely explored in ruminants. The aim of this study was to examine the precise effects of CCK amphibian analogue, cerulein, on small-intestinal myoelectric activity in rams in the course of chronic experiments. Five rams underwent implantation of bipolar platinum electrodes to the duodenal bulb, the distal duodenum and jejunum. During continuous myoelectrical and motor recordings, 0.15 M NaCl or the various doses of cerulein were administered intravenously. Short infusions of the smallest dose of cerulein exerted a slight and mostly insignificant effect on the duodenalbulb and the duodenal myoelectric activity index (MAI) values. In the duodenal bulb, the effects of cerulein on myoelectric activity were dose-dependent and closely related to the phase of the MMC. In the duodenum, the higher doses of the hormone evoked short stimulatory response followed by longer inhibitory biphasic effects on MAI. These effects were inversely related to the duration of hormone injection. Infusions of hormones at the higher doses caused a less pronounced biphasic effect. It is concluded that cerulein exerts an inhibitory effect upon the myoelectric activity of the duodenal bulb and a strong stimulatory and inhibitory (biphasic) effect on duodenal motility in sheep.