Figure 10. I _Nab is not blocked by Cs⁺ .

A, effects of low Na⁺ saline on the holding current of CCs patched with a pipette solution containing 140 mM CsCl and clamped at −50 mV. Bath‐applied low Na⁺ salines (NMDG‐ (Aa) or a Tris‐ (Ab) replaced) decreased the holding current value, indicating that I _Nab is not inhibited by Cs⁺. Mean holding current amplitude: −35.3 ± 13.4 pA versus −26.8 ± 13.5 pA, in control and NMDG‐containing saline, respectively, n = 15 cells, P < 0.05 ( = 0.0256), Wilcoxon matched‐pairs signed‐rank test and −28.9 ± 13.5 pA versus −19.3 ± 14.6 pA, in control and Tris‐containing saline, respectively, n = 39 cells, P < 0.0001, Wilcoxon matched‐pairs signed‐rank test). B, recordings of steady‐state currents in CCs filled with Cs⁺ and clamped at −30 mV. Ba, bath application of low Na⁺ (NMDG substitution) reduced the amplitude of membrane currents evoked by voltage step commands (150 ms duration, 10 mV decrements). The I‐V relationship plotted in Bb shows that I _Nab is linear in the voltage range from −110 to −40 mV. E _rev was determined as the x‐axis‐intercept value calculated from extrapolated linear regression of currents recorded in control and low Na⁺ conditions. [Color figure can be viewed at wileyonlinelibrary.com]