GLUCOSE-TRANSPORTER ISOFORM (GLUT)-2 EXPRESSION IN BETA-CELLS OF LONG-TERM SYNGENEIC ISLET GRAFTS

Syngeneic islets were transplanted into the liver of streptozotocin (S TZ)-induced diabetic LEW.1W rats, and the expression of the glucose tr ansporter isoform GLUT 2, an essential component of the glucose-sensin g mechanism of the pancreatic beta-cell, was determined in the grafted islet tissue. Graft-bearing liver was obtained 12, 36, and 60 weeks a fter transplantation, and tissue sections were immunoperoxidase staine d for GLUT 2 and major islet peptides. Islet cell aggregates of differ ent sizes were found in the portal tract and in juxtaposition to the h epatocytes. At all time points, beta-cells in the grafts displayed GLU T 2 expression comparable to that of islets in nondiabetic rats, Islet cells containing immunoreactive insulin and islet amyloid polypetide were plentiful, while those staining positive for glucagon and somatos tatin were scarce in these grafts. The results show that beta-cells in islets engrafted in the liver, although initially exposed to chronic hyperglycemia, have the capability of stably expressing GLUT 2 over lo ng-term periods.