Effect of cholecystokinin on myoelectric activity of small bowel of the dog.

The effect of cholecystokinin on the myoelectric activity of the small intestine was determined in conscious dogs. Six animals were implanted with electrodes along the small intestine, and a cannula was placed in the stomach. A second cannula was inserted into the duodenum in three animals, and a pancreatic fistula was prepared in three animals. Recordings were made in the fasted state, during the intravenous infusion of either saline or cholecystokinin-octapeptide (CCK-OP), during the intraduodenal infusion of either saline or L-tryptophan, and during the fed state. CCK-OP disrupted the fasted pattern of myoelectric activity, caused a dose-dependent increase in spike potentials, and caused a dose-dependent increases in pancreatic protein secretion. Stimulation of myoelectric activity occurred at doses that produced submaximal protein secretion; however, the stimulation was not identical to that seen with feeding. Intraduodenal infusion of L-tryptophan increased pancreatic protein secretion, interrupted the fasted pattern of motility, and induced a pattern similar to that seen with feeding. We conclude that CCK alters small intestinal motility and may play a role in the changes in small-bowel motility caused by the ingestion of food.