Potassium Channel Openers Reduce the Caspase-3 Expression of Triamcinolone-Treated Retinal Pigment Epithelial (ARPE19) Cells

Abstract

ABSTRACTOur objective was to alleviate the reduction of viability and caspase-3 expression alteration of cultured retinal pigment epithelial (ARPE19) cells in the presence of triamcinolone acetonide (TA) using potassium (K+) channel openers: pinacidil (PIN) and P1060. Four groups were compared: cells only; cells treated with TA (0.1 mg/mL); cells pretreated with either PIN or P1060 for 30 minutes before TA administration; and cells treated with either PIN or P1060 only. The difference in cell numbers in the presence of TA over 1, 3, or 5 days was performed by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell numbers under the treatment of a single concentration of TA or in concomitant administration of a single concentration of the K+ channel openers were quantified by using DAPI nuclear stain. Gene expressions of caspase-3 were also determined by following different treatments. Results were analyzed by using ANOVA, and p < 0.05 was considered significantly different between groups. TA reduced the number (%±SD) of ARPE19 cells to 50.2 ± 2.3% (control = 100 ± 4.9%, p < 0.001) after 1 day of exposure. Similar extents of reductions (i.e., about 50% of the controls) were also observed on days 3 and 5, and both PIN and P1060 reversed this TA-induced reduction of cell viability. The TA-induced caspase-3 level alteration was significantly reduced when the cells were pretreated with either PIN or P1060. TA-induced reduction of viability could be alleviated by the application of K+ channel openers, and this effect was at least partly due to the inhibition of caspase-3 expression.