Inhibition of the linopirdine- and chromanol 293B–sensitive currents in MCs of the stria vascularis by K⁺_e. (A–C) Representative whole-cell outward current recordings from MCs under conditions when Cl⁻ current was suppressed with 100 µM niflumic acid and when K⁺_e was increased from 0 to 150 mM. Currents were elicited from a holding potential of −70 mV using a family of voltage steps ranging from −90 to 60 mV for 1.5 s with a 10-mV increment, followed by a voltage step to −20 mV. (D) The current reduction resulting from the increased K⁺_e in comparison with the prediction by the GHK equation. The relative currents were calculated by normalizing the currents at different K⁺_e to the current obtained at 1 mM K⁺_e at the test potential of 40 mV. The relative currents obtained (n = 8) were significantly smaller than the predicted values when K⁺_e is 20, 50, or 150 mM. (E) Dose-dependent inhibition of the outward currents from MCs by linopirdine at the test potential of 40 mV. The half-inhibition concentration was 4.25 ± 0.06 µM (n = 5). Typical currents before and after the application of 10 µM linopirdine were shown in the inset. (F) Currents recorded from MCs in 1 mM K⁺_e before (top) and after (bottom) the application of 100 µM chromanol 293B. The same voltage protocol described in A–C was used. (G) Dose-dependent inhibition of the outward current at the test potential of 40 mV from MCs by chromanol 293B (n = 7 for 50 µM; n = 6 for 100 µM).