Figure 8. Effects of the knockdown of AQP8 gene expression with AQP8 siRNA (siAQP8) on the AQP8 mRNA level and the viability of cultured RPE cells. As negative control, scrambled nontargeted siRNA (siNon; 10 nM) was used. siRNA transfection was performed 24 h before the addition of 100 mM NaCl or CoCl₂ (150 µM). In A and B, the mRNA level is shown as folds of unstimulated control. A: Effects of siAQP8 and siNon on the level of AQP8 mRNA in cells cultured for 0, 6, and 24 h under unstimulated control conditions in serum-free medium. siRNA transfection was performed 24 h before. B: Effects of siAQP8 (10 nM) and siNon on the level of AQP8 mRNA in cells cultured for 6 h in a high-NaCl medium and for 24 h in the presence of CoCl₂, respectively. C: Viability of RPE cells. The data were obtained in cells cultured for 24 h in iso- (control) and hyperosmotic (high NaCl) media, and in the presence of CoCl₂, respectively, and are expressed as percent of unstimulated control (100%). Each bar represents mean ± standard error of the mean (SEM) obtained in five to eight independent experiments using cell lines from different donors. Significant difference vs. unstimulated control: *p<0.05. Significant difference vs. siNon and vs. NaCl and CoCl₂ controls, respectively: ●p<0.05.