The action of synthetic secretin, cholecystokinin-octapeptide and combinations of these hormones on the secretion of the isolated perfused rat pancreas.

Determinations of dose-response curves for synthetic secretin and for the octapeptide of cholecystokinin (CCK-8) in the isolated perfused rat pancreas reveal that both secretin and CCK stimulate the pancreatic secretory flow and enzyme secretion. The maximal secretory flow evoked by CCK-8 (1.75 +/- 0.24 microliter/min) equals that evoked by secretin, while the protein output (57.1 +/- 6.3 microgram/min) is approximately twice as high. Stimulation by secretin combined with CCK-8 results in summation of the hydrokinetic action and potentiation of the ecbolic action of these hormones. Since the secretory parameters decrease by supramaximal stimulation, the dose-response curves are biphasic. The secretion of pancreatic enzymes correlates significantly (p less than 0.0005) with the protein output. However, the ratio of amylase, lipase and chymotrypsinogen to protein depends on the degree of pancreatic stimulation in so far as amylase secretion increases significantly (p less than 0.01) more markedly than that of both other enzymes.