To investigate the effect of secretiti upon islet hormone secretion, highly purified porcine secretin was perfused at 0.0001, 0.001, 0.01, and 0.1 clinical unit (CU)/ml in the isolated normal dog pancreas. The lowest concentration of secretin, a level which is within the physiologic range, significantly suppressed glucagon release and stimulated somatostatin release but was without significant effect on insulin release. At each concentration of secretin tested glucagon was dramatically suppressed and somatostatin was significantly stimulated, both in a dose-dependent manner. B-cell activity was first augmented by the concentration of 0.001 CU/ml (94 pM) of secretin.
These data demonstrate that physiologic levels of secretin suppress pancreatic A-cell activity in the isolated dog pancreas.