Objective To investigated whether Acid-sensing ion channel 1 a (ASIC1a) is expressed in the retinal pigment epithelium (RPE) cells and whether it is involved in the function of these cells.Methods Real time revere transcription-polymerase chain reaction (RT-PCR) and Western blotting were used to analyze the ASIC1a expression in ARPE-19 cells during oxidative stress induced by hydrogen peroxide (H2O2 ).Furthermore,blockage or overexpression of ASIC1a in RPE cells were obtained using inhibitors (amiloride and PCTxl ) or by the transfection of cDNA encoding hASIC1a.Cell viability was determined using the methyl thiazol tetrazolium (MTT) assay.Results The RT-PCR and Western blot results showed that both the mRNA and the protein of ASIC1a are expressed in RPE.Blockade of ASICs by amiloride in normal RPE cells resulted in cell death,indicating that ASICs play an important physiological role in RPE cells.Furthermore,overexpression of ASIC1a in RPE increased cell survival after oxidative stress induced by H2O2.Conclusion ASIC1a is functionally expressed in RPE cells and may play an important role in the physiological function of RPE cells in protecting them from oxidative stress. Key words: Acid-sensing ion channel 1a; Retinal pigment epithelium; Oxidative stress