Figure 3.

Low Na⁺ hyperpolarizes while high Na⁺ depolarizes DCT membrane. A recording showing I_K reversal potential in the DCT cells of (A) WT and (B) Ks-Kir4.1 KO mice on a normal Na⁺ (black), low Na⁺ (red), or high Na⁺ (green) diet for 7 days. (C) A bar graph summarizing I_K reversal potential in WT and Ks-Kir4.1 KO mice on different Na⁺ diets. For the measurement of I_K reversal potential, the bath solution contained 140 mM NaCl and 5 mM KCl, and the pipette solution contained 140 mM KCl. (D) A bar graph summarizing the results of experiments in which NPPB-sensitive Cl⁻ currents in the DCT were measured at −60 mV with the whole-cell recording in the WT or in Ks-Kir4.1 KO mice on a normal Na⁺ (black), low Na⁺ (red), or high Na⁺ (green) diet for 7 days. For the measurement of NPPB-sensitive Cl⁻ current, the bath solution contained 140mM KCl, 2 mM MgCl₂, 1.8 mM CaCl₂, and 10 mM HEPES (pH 7.4). The significance was determined by one-way ANOVA (for more than two groups) or by t test (for two groups).