Fig. 6.

ANO1 outward current is activated close to maximum by SR Ca²⁺ release. a Ca²⁺-concentration dependence experiments of ANO1 currents were performed by elevating cytosolic Ca²⁺ concentrations via perfusion with the patch pipette solution from the physiological level (+0, n = 5) to +2 (n = 5), +5 (n = 9), +7.5 (n = 5), and +13 µM (n = 8). Plots of Ca²⁺ dependence of the outward Cl⁻ current at +80 mV (top graph) and Ca²⁺ dependence of the inward Cl⁻ current at −140 mV (bottom graph) are shown. Vertical blue arrow indicates Cl⁻ current stimulation by SR Ca²⁺ release, which raises cytosolic Ca²⁺ to ~ 15 µM⁵². Representative recordings of ANO1 currents (3-s pulse protocol) at different elevations of intracellular Ca²⁺ concentrations are depicted on the right. Scale bars, 1 s (horizontal), 40 pA pF⁻¹ (vertical). b Current–voltage relationship under physiological conditions i.e., +0 Ca²⁺ addition (n = 5, left graph) and after addition of +13 µM Ca²⁺ to the cytosol (n = 8, right graph). Orange arrow indicates I_max at +80 mV and green arrow at −140 mV. Data are presented as mean ± s.e.m.; P determined by unpaired Student’s t-test