Effects of gastrectomy on insulin secretion in rats

To examine the relative importance of the stomach for the enteroinsular axis, the portal insulin secretion was measured in the rats with gastrectomy, after intraduodenal (I.D.) infusion of 0.5 g/kg glucose and after intravenous (I.V.) infusion of the same deal of glucose, respectively. Portal plasma gastrin was decreased from 100 pg/ml to 5 pg/ml by gastrectomy. Blood sugar level after I.D. and I.V. infusion of glucose in the rats with gastrectomy was similar to controls. Insulin release to I.D. infusion of glucose was slightly lower at 30 minutes in the gastrectomized rats compared with controls, while insulin secretion to I.V. infusion of glucose was similar to controls. These results suggest that endogenous gastrin has no insulinotropic effect and that the stomach has no direct effect on glucose-induced insulin release.