Effect of lyotropic anions on DICR activity. (A) Typical results of R-CEPIA1er fluorescence in cells in the absence (Control, left) and presence of 10 mM perchlorate (ClO₄⁻, center) or 10 mM thiocyanate (SCN⁻, right). High [K⁺] solution ranging from 5 to 61 mM (symbols shown in left) was applied at 30 s after starting (blue arrowheads). (B) [K⁺] dependence of fluorescence change (F/F₀) in cells in the absence (Cont, black) and presence of 10 mM perchlorate (ClO₄⁻, red) or 10 mM thiocyanate (SCN⁻, blue). Data are means ± SD (n = 9, N = 3). (C and D) Fluorescence change by 61 mM K⁺ (C) and EC₅₀ values for K⁺ (D). Data are means ± SD (n = 9, N = 3) and were analyzed by one-way ANOVA with Dunnett’s multiple comparisons test. EC₅₀ values were significantly reduced with lyotropic anions. (E) Caffeine dependence of R-CEPIA1er fluorescence (F/F₀) in cells in the absence (Cont, black) and presence of 10 mM perchlorate (ClO₄⁻, red) or 10 mM thiocyanate (SCN⁻, blue). Data are means ± SD (n = 9, N = 3). (F and G) Fluorescence change by 20 mM caffeine (F) and EC₅₀ values for caffeine (G). Data are means ± SD (n = 9, N = 3) and were analyzed by one-way ANOVA with Dunnett’s multiple comparisons test. No significant changes were observed by lyotropic anions. n is the number of wells and N is the number of independent experiments.