Objective  To investigate the protective effects of riluzole, a sustained activator of K2P subfamily member TRAAK potassium channel, in human retinal pigment epithelium (hRPE) cells with oxidative induce by tert-butyl hydroperoxide (t-BHP) in vitro, and to evaluate the possible involvement of K2P in the cytoprotective function of retina degeneration diseases. Methods  The third to fifth passage of the primary cultured hRPE cells were used in the following experiments．hRPE cells were divided into seven groups: normal control group.t-BHP (300  mu;mol/L) group.t-BHP with riluzole (2, 5, 10, 20  mu;mol/L) group and riluzole (10  mu;mol/L) group. The apoptosis was measured by the 3(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, annexinV/PI double staining flow cytometry. Changes of cells and nuclei morphology were observed under a phase contrast microscope and a fluorescence microscope after 4 prime;, 6-diamidino-2-phenylindole (DAPI) staining. Immunofluorescence 1abelling was carried out to analysis the expression of TRAAK. Results  After 24 hours incubation with 300  mu;mol/L t-BHP, the cells viability decreased to (58.7 plusmn;12.2)% as compared to the normal control groups. The cell viability of t-BHP with riluzole group at different concentrations was higher than the t-BHP group, while 10  mu;mol/L riluzole showed maximally protective effect on hRPE death induced by t-BHP（t=4.84.P＜0.05）. Riluzole remarkably decreased pyknotic nucleus and cell swelling when compared with t-BHP group. Morphology of cells was fusiform with the uniform elliptic nuclei in normal and riluzole group. The Results of annexinV/PI double staining flow cytometry showed that ratio of normal cells were （97.6 plusmn;1.3）%, （70.3 plusmn;7.0）%, （86.9 plusmn;5.2）%, （93.9 plusmn;1.5）% in normal group.t-BHP group.t-BHP with riluzole group and riluzole group respectively. The ratio significant decreased in t-BHP group when it was compared with the other groups (t=7.53, 4.59, 6.49, respectively.P＜0.05). By contrast with normal group and riluzole group, the ratio of normal cells in t-BHP with riluzole group had no statistical significance（t=2.94, 1.91, respectively.P＞0.05）. Riluzole (10  mu;mol/L) also significantly decreased the ratio of early stage apoptotic cells from (25.50 plusmn;8.02)% to (1.20 plusmn;0.72)% in t-BHP injured groups （t=7.13，P＜0.05）. The ratio of early stage apoptotic cells significant decreased in t-BHP group when it was compared with the normal group and riluzole group （t=7.07, 5.94, respectively.P＜0.05）. By comparison with normal group and riluzole group, there are no statistical significance in t-BHP with riluzole group（t=0.06, 1.18, respectively.P＞0.05）. The mean gray values of TRAAK expression were 0.040 plusmn;0.003, 0.041 plusmn;0.001, 0.049 plusmn;0.001, 0.055 plusmn;0.001 in normal group.t-BHP group.t-BHP with riluzole group and riluzole group respectively. TRAAK density was significantly higher in t-BHP with riluzole group and riluzole group（t=7.40, 12.70, respectively.P＜0.05）. Conclusions  Riluzole can protect hRPE cells against oxidative injury-induced cell death at early apoptosis stage. The mechanism may relate to that riluzole can promote the expression of K2P TRAAK potassium channel.

Citation： 沈朝兰,李楚,朱晓波,郑文斌,夏仁春. Effect of TRAAK activator riluzole on t-BHP induced injury of human retinal pigment epithelial cells. Chinese Journal of Ocular Fundus Diseases, 2013, 29(4): 400-405. doi: Copy

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