Glucose-dependent insulinotropic action of cholecystokinin octapeptide in the isolated perfused rat pancreas.

Whether cholecystokininoctapeptide (CCK-8) stimulates insulin secretion at submaximal or supramaximal levels for pancreatic exocrine secretion was investigated. CCK-8 was delivered to the isolated perfused rat pancreas by a linear gradient ranging from 0 to 1,100 or 0 to 220 pg/ml at two different glucose concentrations. At 2.8 mM glucose CCK-8 was not insulinotropic even at supramaximal stimulation for exocrine pancreatic secretion. At 15.8 mM glucose CCK-8 was insulinotropic starting already at concentrations which were submaximal for stimulation of exocrine pancreatic secretion. It was concluded that CCK-8 warrants consideration as a hormone involved in the enteroinsular axis.