pH is decreased in transplanted rat pancreatic islets

Carlsson, Per-Ola, Astrid Nordin, and Fredrik Palm. pH is decreased in transplanted rat pancreatic islets. Am J Physiol Endocrinol Metab 284: E499–E504, 2003. First published November 5, 2002; 10.1152/ajpendo.00156.2002.—Recent studies of transplanted pancreatic islets have indicated incomplete revascularization. We investigated the pH, in relation to oxygen tension (PO2), in endogenous islets and islets syngeneically transplanted to the renal subcapsular site of nondiabetic and streptozotocin-diabetic recipients. Tissue pH and PO2 were measured using microelectrodes. In the endogenous islets, tissue pH was similar to that in arterial blood. In the transplanted islets, tissue pH was 0.11–0.15 pH units lower. No differences in islet graft pH were seen between nondiabetic and diabetic animals, and none if the islet grafts were investigated 1 day or 1 mo posttransplantation. The PO2 in the endogenous islets was 35 mmHg. Transplanted islets had a markedly lower tissue PO2 both 1 day and 1 mo after transplantation. A negative correlation between the tissue PO2 and the hydrogen ion concentration was seen in the 1-mo-old islet transplants in diabetic animals. In conclusion, decreased PO2 in transplanted islets is associated with a decreased tissue pH, suggesting a shift toward more anaerobic glucose metabolism after transplantation.