Figure 4.

Deletion of neural precursor cell-expressed developmentally downregulated protein 4-2 (Nedd4-2) abolished the effect of dietary K⁺ intake on renal outer medullary K⁺ (ROMK) channel activity in the late distal convoluted tubule (DCT2)/initial connection tubule (_iCNT). A and B: sets of whole cell recordings showing tertiapin Q (TPNQ; 400 nM)-sensitive K⁺ currents (ROMK) of the DCT2/_iCNT in male control mice on a high K⁺ (HK) diet or low K⁺ (LK) diet for 7 days (A) and in male kidney-specific Nedd4-2 knockout (Ks-Nedd4-2 KO) mice on different K⁺ diets (B). K⁺ currents were measured with a gap-free protocol at −40 mV. C: scatterplot summarizing each single value and mean value (at the left of each column) of the experiments in which TPNQ-sensitive K⁺ currents were measured at −40 mV in the DCT2/_iCNT of control mice and Ks-Nedd4-2 KO mice on different K⁺ diets for 7 days (n = 6 tubules). The results obtained in mice on normal K⁺ (NK; shown in Fig. 1C) are also included for the comparison (indicated by a dotted line). Significance was determined by two-way ANOVA. Nedd4l, neural precursor cell-expressed developmentally downregulated 4-like.