Fig. 6.

Dietary K⁺ maneuvers affect epithelial Na⁺ channel (ENaC) localization. Kidney tissue from mice maintained on varying K⁺ diets for 10 days was fixed and immunostained for γ-ENaC (green). A: dietary K⁺ loading shifted γ-ENaC localization from diffuse to apical staining, which was more prominent for the KCl diet than for the K⁺ basic diet. Three-dimensional z-stacks were acquired and maximum intensity projected to visualize apical versus diffuse ENaC localization. B: quantification of γ-ENaC localization was performed using a fluorescence intensity line profile plot from 30 representative cells over different 3 experiments. Results were averaged and plotted to compare the fluorescence intensity distribution between groups. All statistics and analysis were performed using two-way ANOVA with Dunnett’s post hoc analysis to evaluate for significant changes between varying K⁺ diets and the control (Ctrl) diet. KCl- and K⁺ basic diet-fed mice displayed significantly different γ-ENaC distributions compared with control mice (P ≤ 0.0001), while low-K⁺ fed mice had a similar distribution to control. Specifically, KCl-fed mice exhibited γ-ENaC localization preference for the luminal membrane and decreased γ-ENaC within the cytoplasmic region. Compared with control mice, KCl diet-fed mice had γ-ENaC distribution that was significantly different from 2.0–6.4 µm from the lumen (*P ≤ 0.05, **P ≤ 0.01, and ****P ≤ 0.0001). K⁺ basic diet-fed mice displayed a slightly reduced cytoplasmic γ-ENaC distribution that was significantly different from control mice between 2.2–6.4 µm from the lumen. Low-K⁺ diet-fed mice had a similar γ-ENaC distribution compared with control mice, with a few significant points from 5.1–6.4 µm from the lumen.