Importance of Kir2.1 on DICR platform. (A) Resting membrane potential of cells infected with 5 BV (left) or BV without Kir2.1 (−Kir2.1; right). Data are means ± SD (n = 10, N = 3 for 5 mM [K⁺] with 5 BV; n = 16, N = 3 for 50 mM [K⁺] with 5 BV; n = 10, N = 3 for 5 mM [K⁺] with −Kir2.1 and n = 14, N = 3 for 50 mM [K⁺] with −Kir2.1) and were analyzed by two-way ANOVA with Bonferroni’s multiple comparisons test. (B) Typical results of R-CEPIA1er fluorescence in cells infected with 5 BV (left) and BV without Kir2.1 (right). High [K⁺] solution ranging from 5 to 61 mM (symbols shown in left) was applied at 30 s after starting (blue arrowheads). (C) Typical results of ER [Ca²⁺] measurement in cells with 5 BV (left), without Kir2.1, without Kir2.1 and β1a, and without Kir2.1 and Stac3. (D) Resting ER [Ca²⁺] in cells infected with 5 BV, BV without Kir2.1 (−Kir2.1), Kir2.1 and β1a (−Kir2.1, −β1a), or Kir2.1 and Stac3 (−Kir2.1, −Stac3). Averaged R-CEPIA1er fluorescence at the initial 30 s was normalized by averaged fluorescence at the last 30 s. Data are means ± SD (n = 8, N = 3) and were analyzed by one-way ANOVA with Dunnett’s multiple comparisons test. n is the number of cells (A) or wells (D) and N is the number of independent experiments.