Potentiating effect of secretin on cholecystokinin-stimulated pancreatic secretion in dogs.
A possible potentiating effect of cholecystokinin octapeptide (CCK-OP) on the action of secretin on exocrine pancreatic secretion was studied in five dogs with gastric fistulas and modified Herrera pancreatic fistulas. Secretin in a dose, 2.45 pmol (0.03 clinical units) X kg-1 X h-1, that mimics the plasma secretin level in the postprandial state increased pancreatic bicarbonate secretion, but the increase was not statistically significant. CCK-OP in graded doses, 26.2, 52.5, 109, and 219 pmol (0.03, 0.06, 0.125, and 0.25 microgram) X kg-1 X h-1, given intravenously produced a significant increase in both bicarbonate and protein secretion, and the increase was dose related. The plasma concentrations of immunoreactive CCK during intravenous infusion of CCK-OP in doses of 26.2 and 52.5 pmol X kg-1 X h-1 were found to mimic the postprandial plasma concentrations of immunoreactive CCK in eight dogs. When CCK-OP in four graded doses was added to intravenous infusion of secretin, 2.45 pmol X kg-1 X h-1, the actual bicarbonate output at each dose level of CCK-OP was greater than the sum of the bicarbonate outputs produced by secretin alone and CCK-OP alone in a corresponding dose. Thus, we conclude that the action of secretin in a physiological dose that mimics the plasma level of secretin after a meal is potentiated by CCK-OP in a dose range that produces a plasma CCK-OP level comparable with that in the postprandial state and vice versa. The study indicates that, like secretin, CCK-OP is another necessary agent for pancreatic secretion of bicarbonate during digestion.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D002766:Cholecystokinin / Q000494:pharmacology*; D004285:Dogs / Q000378:metabolism*; D004357:Drug Synergism; D004435:Eating; D007263:Infusions, Parenteral; D010179:Pancreas / Q000378:metabolism*; D011863:Radioimmunoassay; D012633:Secretin / Q000097:blood / Q000494:pharmacology*; D012844:Sincalide / Q000494:pharmacology; D013268:Stimulation, Chemical
D001639:Bicarbonates; D012633:Secretin; D002766:Cholecystokinin; D012844:Sincalide