Effects of high concentration of glucose on Na-K-ATPase expression of human retinal pigment epithelium cell

Objective: Diabetic macular edema is an outcome of damage of retinal inner and outer barrier. Retinal pigment epithelium (RPE) plays a critical role in retinal fluid transfer; while Na-K-ATPase is an important enzyme in the process of fluid transportation of subretinal space. Here in the experiment, we investigated the effects of high concentration of glucose on Na-K-ATPase expression in human RPE. Methods: ARPE-19 cells were cultured for 4 weeks in 24 wells culture plate. The cultured cells were divided into high concentration of glucose-cultured group (glucose addition at 30 mmol/L) or control group(containing 7 mmol/L glucose). Reverse transcription polymerase chain reaction and Western-blot were used to evaluate the expression of Na-K-ATPase in cells after cultured for 2 or 4 weeks. Results: High concentration of glucose downregulated the mRNA expression both Na-K-ATPase α1 and β1 subunit. The OD ratio of Na-K-ATPase α1 to β-actin was 0.17 and 0.23 respectively after culture for 2 or 4 weeks in high glucose group and 0.37 and 0.36 in normal group, and that of Na-K-ATPase β1 was 0.69 and 0.41 in high glucose group, 0.98 and 0.83 in control group. Protein level of Na-K-ATPase β was lower in high glucose group than in normal group. The OD ratio to β-actin was 0.51 and 0.25 respectively after cultured for 2 or 4 weeks in high glucose group and 0.37 and 0.36 in normal group. Conclusion: The expression of mRNA and protein of Na-K-ATPase is reduced in human retinal pigment epithelium at the cultured condition of high concentration of glucose. This result suggests that high concentration of glucose may participate in the pathogenesis of diabetic macular edema.