Endocrine function of the heterotopic pancreatic allotransplant in dogs. I. Normal and rejection.

After heterotopic pancreatic allotransplantation in dogs and in the absence of rejection there was a fasting normoglycemia with a marked hyperinsulinemia. On intravenous glucose tolerance testing and intravenous glucagon testing, the blood sugar response of dogs receiving no immunosuppression was normal but the response in dogs receiving immunosuppressive therapy was exaggerated. There was a marked increase in the insulin response compared with normal animals whether or not immunosuppressive therapy was administered. The first endocrine even during allograft rejection seemed to be a drop in the pancreatic insulin reserve as demonstrated by plasma insulin results during a glucagon test; occurring 2 to 3 days before clinically overt rejection. This was also found on glucose tolerance testing. A rise in the fasting plasma insulin occurred next, 1 to 2 days before a rise in the fasting blood sugar. As the rejection process progressed, the plasma insulin levels subsequently dropped until the death of the animal. If, during a rejection process, the blood sugar did not rise above 150 mg/100 ml and the plasma insulin level did not drop below the lower limit of normal the rejection was usually reversible with intravenous methylprednisolone.