Figure 4. .

Upregulation of glucose transporters in Hfe^−/− primary RPE cells. (A) Real-time PCR analysis showing mRNA levels of sodium-coupled glucose transporter SGLT1 and facilitative glucose transporters (GLUT1-4) in Hfe^+/+ and Hfe^−/− RPE cells from passage three or four. (B) Uptake of [³H]-3-O-methyl-D-glucose was measured in passage two, three, and four (P2, P3, and P4) in Hfe^+/+ and Hfe^−/− RPE cells. Uptake was measured for 2 minutes at 37°C in the absence of Na⁺ with 1 μCi/well of [³H] 3-O-methyl-D-glucose and 50-μM unlabeled glucose. NMDG chloride was used to substitute for NaCl in the uptake medium. (C) Na⁺-independent and Na⁺-dependent uptakes of [³H]-3-O-methyl-D-glucose were also measured in Hfe^+/+ and Hfe^−/− RPE cells (P2). *P < 0.05; **P < 0.01; ***P < 0.001.