The enteral insulin-stimulation after pancreas transplantation in the pig.

The insulin responses to an oral glucose tolerance test (OGTT) and in intravenous glucose infusion (IVGI), designed to copy the changes in serum glucose concentrations found during OGTT, were measured in four pigs before and after heterotopic pancreatico-duodenal allotransplantation and total pancreatectomy. After transplantation and total pancreatectomy a remarkable hyperinsulinaemia occurred during OGTT and IVGI, reflected by an almost two-fold increment in the insulinogenic index after transplantation. This finding might be explained by drainage of the transplanted pancreas into the systemic circulation instead of the portal vein. The magnitude of the enteral stimulus, i. e. the incretin effect on insulin secretion during OGTT was unchanged after transplantation, suggesting that the incretin effect is not mediated by neural influences upon the endocrine pancreas.