Abstract： Objective To investigate Kir4.1 expressions in Müller cells under high glucose conditions and treatment of pigment epithelium derived factor (PEDF).Methods Cultured rat Müller cells were divided into control group (5 mmol/L glucose),high glucose group (25 mmol/L glucose),PEDF treatment group (25 mmol/L glucose+ 100 ng/ml PEDF) and intervention control group(25 mmol/L glucose +phosphate buffer solution). Kir4.1 expressions were measured by Western blot and real-time reverse transcription polymerase chain reaction (RT-PCR). Reactive oxygen species (ROS) productions were measured using 2′7′-dichlorofluorescin diacetate and glutathione peroxidase (GPx)expressions were studied by real-time RT-PCR.Results By Western blot and real-time RT-PCR,it was found the expressions of Kir4.1 decreased obviously under high glucose conditions (real-time RT-PCR:t=4.12,P＜0.05; Western blot:t=3.53,P＜0.05) ; simultaneously,ROS generation was increased (t=3.76,P＜0.05) and GPx level was decreased (t=3.18,P＜0.05).PEDF treatment inhibited the high glucose-induced Kir4.1 down regulation (real-time RT-PCR:t =3.66,P＜0.05 ; Western blot:t =6.43,P＜0,01 ) and decreased ROS generations (t=4.11,P＜0.05) and increased GPx levels (t=5.12,P＜0.01).Conclusions The high glucose can supress Kir4.1 expressions in Müller cells by oxidative stress,and PEDF can ameliorate these effects.