Fig. 2: Effects of dietary Na⁺ intake and ENaC inhibition on urine K⁺ excretion in Kir4.2^+/+ and Kir4.2^−/− animals.

A Urine K⁺ excretion at baseline and on 0 K diet for indicated timepoints in Kir4.2^+/+ and Kir4.2^−/− mice. Diet contained 0% Na⁺ with 0 K (purple and green). B Urine K⁺ excretion on day three of 0 K from animals treated with normal Na⁺ or as in (A). Note black and red data (both genotypes on 0.3% Na⁺) are from panel 1 h (p = 0.0011 and 0.0082). Urine (C) K⁺ excretion at baseline and on 0 K diet in Kir4.2^−/− mice. Amiloride was added to drinking water at indicated time point (p = 0.02). D Comparison of urine K⁺ excretion between Kir4.2^+/+ and Kir4.2^−/− mice after three days of consuming a 0 K diet with and without amiloride treatment (p = 0.0027 for interaction). Blood (E) K⁺ (p = 5 × 10⁻⁶) (F) Na⁺ (p = 0.038), (G) Cl^- (p = 0.044), and (H) HCO₃⁻ from Kir4.2^−/− mice treated as in (C). N = 5 for all, except day 1 of 0 K in 2a where n = 2 and 4 (3 Kir4.2^+/+ and 1 Kir4.2^−/− animals did not consume diet and so data were not included in analysis), and N = 6 for WT 0 K in (D). #, P < 0.05 for genotype difference at indicated timepoints by two-way ANOVA with or without repeated measures followed by Sidak’s multiple comparison test. *P < 0.05 by unpaired t test. ^††p < 0.05 for interaction by two-way ANOVA. All tests were two-sided. Data presented as mean ± sem.