Secretin/cholecystokinin-stimulated secretion of trypsinogen and trypsin inhibitor in pure human pancreatic juice collected by endoscopic retrograde catheterization.

Pure pancreatic juice was collected by endoscopic retrograde catheterization of the papilla of Vater from 10 fasting patients without known pancreatic disease. Secretin was given intravenously as a bolus dose at the beginning of the examination and cholecystokinin was given in the same way 15 min later. The juice was siphoned for 25 min and collected in 1-min fractions. Pancreatic secretory trypsin inhibitor, PSTI, and trypsinogen were measured by an immunochemical method. Secretin produced an increase in hydrogencarbonate and a decrease in chloride secretion. Cholecystokinin caused a prompt increase in the concentration of both PSTI and trypsinogen. The ratio between these was constant, suggesting a strictly parallel secretion. The effect of cholecystokinin on secretion of total protein when given as bolus dose was of short duration, with a half-life of action of about 3.5 min.