Effects of substance P and substance P-(6-11) on hormone release from isolated perfused pancreas: their opposite actions on rat and canine islets

The effects of substance P (SP) and SP-(6-11) (SP6-11) on hormone secretion from the isolated perfused pancreas were compared in rats and dogs under the same conditions. In the rat, SP inhibited Insulin secretion in a dose-dependent manner in a concentration range of 0.1-10 nM. Glucagon secretion was inhibited at a minimal dose of 10 nM SP. No significant effect on somatostatin secretion was obtained. SP6-11 exhibited the identical inhibitory potency as SP on both Insulin and glucagon release from the rat pancreas. In the canine pancreas, by contrast, 1 and 10 nM SP and SP6-11, respectively, potentiated the release of Insulin, glucagon, and somatostatin. Potentiation by SP6-11 was less than that by SP. These results demonstrate species differences in the effects of SP and SP6-11 on the release of pancreatic Hormones.