Changes in sodium or glucose filtration rate modulate expression of glucose transporters in renal proximal tubular cells of rat

Renal glucose reabsorption is mediated by luminal sodium-glucose cotranspor ters (SGLTs) and basolateral facilitative glucose transporters (GLUTs). The modulators of these transporters are not known, and their substrates gluco se and Na+ are potential candidates. In this study we examined the role of glucose and Na+ filtration rate on gene expression of glucose transporters in renal proximal tubule. SGLT1, SGLT2, GLUT1 and GLUT2 mRNAs were assessed by Northern blotting; and GLUT1 and GLUT2 proteins were assessed by Wester n blotting. Renal cortex and medulla samples from control rats (C), diabeti c rats (D) with glycosuria, and insulin-resistant 15-month old rats (I) wit hout glycosuria; and from normal (NS), low (LS), and high (HS) Na+-diet fed rats were studied. Compared to C and I rats, D rats increased (P < 0.05) g ene expression of SGLT2 by similar to 36%, SGLT1 by similar to 20%, and GLU T2 by similar to 100%, and reduced (P < 0.05) gene expression of GLUT1 by m ore than 50%. Compared to NS rats, HS rats increased (P < 0.05) SCLT2, GLUT 2, and GLUT1 expression by <similar to>100%. with no change in SGLT1 mRNA e xpression, and LS rats increased (P < 0.05) GLUT1 gene expression by <simil ar to>150% with no changes in other transporters. In summary, the results s howed that changes in glucose or Na+ filtrated rate modulate the glucose tr ansporters gene expression in epithelial cells of the renal proximal tubule .