Ano1 is activated by Ba²⁺. (A) Representative traces of Ano1 current in inside-out excised patches activated by 1, 10, and 100 µM Ba²⁺. Inside-out excised patches were switched between zero divalent cation (5 mM EGTA with no added Ba²⁺ or Ca²⁺) and Ba²⁺-containing pipette solutions. Ba²⁺ solutions contained 1 mM EGTA, and free Ba²⁺ was calculated from MaxChelator. Traces were recorded at the following voltages: black, 120 mV; red, 80 mV; green, 40 mV; blue, −40 mV; cyan, −80 mV; magenta, −120 mV. (B) Mean amplitude of Ba²⁺-activated current in whole-cell recording at 100 mV. Ba²⁺ was included in the intracellular pipette solution, and current amplitudes were recorded at a time when the currents reached a maximum level. (C) Mean amplitude of Ba²⁺-activated currents in inside-out excised patches. To control for different current amplitudes between patches and rundown, each patch was exposed for 5-s intervals first to 1 mM Ba²⁺, then to the test Ba²⁺ concentration, and then to 1 mM Ba²⁺ again. The amplitude of the current in response to the test Ba²⁺ concentration was then normalized to the mean of the currents in 1 mM Ba²⁺. The data points were fitted to the Hill equation. Error bars are ±SEM.