FUNCTIONAL LOCALIZATION OF GLUCOSE-TRANSPORTER-2 IN RAT-LIVER

Heterogeneity of zonal hepatocytes is important to elicit specific liv er function, We investigated the distribution of glucose transporter 2 (GLUT-2) in normal rat liver by immunostaining and Northern blot anal ysis. GLUT-2 stained by immunohistochemistry was distributed predomina ntly in the periportal hepatocytes and gradually thinned towards the p erivenous zone, Ultrastructural immunostaining of GLUT-2 showed that i t was localized on microvilli of the sinusoidal plasma membrane of hep atocytes but not on the basolateral plasma membrane, Consistent with t he distribution of GLUT-2 protein, the level of GLUT-2 mRNA in peripor tal hepatocytes was 1.9-fold higher than in perivenous hepatocytes sel ectively isolated by the differential isolation technique, In addition , the mRNA level of phosphoenolpyruvate carboxykinase, one of the key enzymes of gluconeogenesis, was also twofold higher in the periportal hepatocytes, These results suggest that GLUT-2 contributes to the func tional difference between periportal and perivenous hepatocytes in glu cose metabolism of the liver.