Insulinotropic and Possible Insulin-like Effects of Secretin and Cholecystokinin-Pancreozymin

The effect of intravenous injection of secretin and cholecystokinin-pancreozymin (C-P) on serum immunoreactive insulin (IRI) in monkeys and rats was measured. Both secretin (7.5 U) and C-P (30 U) injections caused 4- to 5-fold increases in serum IRI of monkeys within 2 min. Only C-P (2 U) injections caused an increase (about 4-fold) in serum IRI of rats, while after secretin (0.5 U) injections there was no change in IRI. The serum glucose decreased in the monkeys following the increased IRI, but in neither species did serum glucose increase and therefore glucose was not the cause of the IRI response. In a separate experiment it was shown that neither secretin nor C-P increases appreciably the glucose uptake of isolated fat cells from epididymal fat pads of rats. (Endocrinology86: 927, 1970)