INTRADUODENAL CHOLECYSTOKININ-OCTAPEPTIDE (CCK-8) CAN STIMULATE PANCREATIC-SECRETION IN THE CALF

The effect of CCK-8 administered into the duodenal lumen and into the systemic blood on pancreatic secretion and duodenal migrating myoelect ric complex (MMC) was studied in four calves. Simultaneous MMC recordi ngs and collections of pancreatic juice were performed on valves that had been fasted overnight. Intraduodenal (0, 100, and 300 pmol/kg body wt) and intravenous (0, 30, and 100/pmol kg) infusions of CCK-8 were made for 5 min during the no spiking activity (NSA) phase of duodenal MMC associated with a nadir of periodic pancreatic secretion. CCK-8 wa s also administered during continuous atropine infusion (5 mu g/kg/min ). Both intraduodenal and intravenous infusions of CCK-8 resulted in m arked pancreatic responses in juice outflow, bicarbonate output, and p rotein output. Atropine decreased pancreatic response (protein output) to intravenous CCK-8 and markedly inhibited the response (juice flow, bicarbonate, and protein output) to intraduodenal CCK-8. Infusions of CCK-8 did not affect the duration of MMC in the duodenum. Plasma CCK increased significantly after intravenous infusion, but remained uncha nged after intraduodenal infusion. In conclusion, CCK-8 can stimulate pancreatic secretion from the duodenal lumen, possibly via a cholinerg ic mechanism in the calf.