Objective To investigate Kir4.1 expressions in Muuml;ller cells under high glucose conditions and treatment of pigment epitheliumderived factor (PEDF）. Methods Cultured rat Muuml;ller 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 2prime;7prime;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 Muuml;ller cells by oxidative stress, and PEDF can ameliorate these effects.
Objective To observe the effects of high concentr at ion glucose on the calcium-activated potassium channel of rabbits′ retinal Müller cells. Methods The rabbits′retinal Müller cells were cultured in vitro under the condition of high concentration glucose, and identified by immunohistochemical staining and transmission electron microscopy. Patch-clamp technique was used to observe the changes of the calcium-activated potassium channel of retinal Müller cells caused by high concentration glucose at different time.Results High concentration glucose could inhibit the calcium-activated potassium channel of cultured retinal Müller cells in a time-dependent manner. Conclusion High concentration glucose may reduce the biological functions of Müller cells by inhibiting calcium-activated potassium channel. (Chin J Ocul Fundus Dis，2003，19：164-167)
ObjectiveTo observe the changes in open probability and protein expression of large conductance Ca2+-activated K+ (BK) channel in retinal vascular smooth muscle cells (RVSMCs) of diabetic rats. MethodsStreptozotocin (STZ)-induced rat diabetic animal model was established by STZ injection intraperitoneally.RVSMCs were isolated by enzyme digestion. The BK currents in control and diabetic groups were recorded by patch clamp technique in single channel configuration. BK channel protein expression in control and diabetic group were measured by Western blot. ResultsCompared with control group, the NP0 of BK channels in diabetic group were significantly increased (t=4.260, P < 0.05). Compared with control group, there was no significant difference inα-subunit protein expression in diabetic group in RVSMCs (t=10.126, P > 0.05); however, β1-subunit protein expression was remarkably increased in diabetic group (t=5.146, P < 0.05). ConclusionThe NP0 of BK channels andβ1-subunit protein expression are increased in RVSMCs of diabetic rats.