Pancreas autotransplantation in pig with systemic or portal venous drainage - Effect on the endocrine pancreatic function after transplantation

The effect of the type of venous drainage of the graft on its endocrine function was studied in two groups of pigs after segmental pancreas autotransplantation. Group 1 comprised 10 pigs with portal venous drainage (PVD) and group 2 comprised 10 pigs with systemic venous drainage (SVD). The graft consisted of body and tail of the pancreas. The pigs were totally pancreatectomized. The pancreatic duct was occluded by neoprene injected into the duct. One week before and 1 and 3 months after transplantation, intravenous glucose tolerance tests (IVGTT) and meal stimulation tests (MST) were performed. Plasma glucose (PG), insulin (INS), C-peptide, glucagon (GLU), and pancreatic polypeptide (PP) were measured during the tests. All pigs had normal fasting PG, 1 and 3 months after PanTx, although MST disclosed significantly higher PG (P < 0.05) during the test after transplantation. In the PVD group, a decrease in INS level during both tests was recorded after PanTx (P < 0.05), while in the SVD group a nonsignificant rise in INS level was recorded compared with before transplant. A significant difference (P < 0.05) in INS levels were present both 1 and 3 mon. after PanTx between the two groups. Pigs with PVD showed a higher (P < 0.05) C-peptide level than pigs with SVD during IVGTT. The initial significant rise in PP during MST and the initial fall in PP during IVGTT recorded in all pigs before transplantation were totally lost after transplantation in both groups. During the tests, PP remained steady and significantly lower than the pretransplantation levels in both groups. A significantly higher GLU level during both IVGTT and MST was observed in SVD compared with PVD 1 month after PanTx (P < 0.05), being more pronounced during MST. This accentuated GLU concentration decreased by 3 months after transplantation, although it was still significantly greater than pretransplantation levels. We conclude that the unnatural mode of delivery of pancreas endocrine secretion to systemic rather than to portal circulation leads to derangements in pancreatic endocrine function in order to maintain glucose homeostasis. This may cause earlier exhaustion of islet cells. Segmental rather than whole organ and duct occlusion rather than exocrine drainage may further contribute to this, shortening the effective life of the graft.