Dose-response study of somatostatin on meal-stimulated levels of pancreatic polypeptide and insulin in the dog.

A dose-response study of the effect of 0.1-5.0 micrograms kg-1 h-1 somatostatin was performed on food-induced rise of pancreatic polypeptide and insulin in 4 dogs. There was a dose-dependent suppression of the release of pancreatic polypeptide and insulin with an ED50 of approximately 0.65 and 0.8 microgram kg-1 h-1, respectively, during the first 45-min period. In the second 45-min period, high doses of somatostatin failed to suppress insulin concentrations whereas, the serum concentrations of pancreatic polypeptide were reduced by a similar degree as in the first 45 min. The differing effects of somatostatin on food-stimulated serum concentrations of insulin and pancreatic polypeptide indicate that somatostatin does not represent a uniform suppressor of pancreatic hormones.