FIGURE 1:

SGK1 and NHERF2 play important roles in Dex-induced activation of NHE3 in mouse ileum. Mice were injected intraperitoneally with Dex at 2 mg/kg body weight. After 4 or 24 h, villi were isolated from the ileum and NHE3 activity was measured in the presence of 50 μM Hoe-694 (NHE1 and NHE2 inhibitor). Increased rates of pH recovery following 4 or 24 h of Dex treatment were observed. (A) Representative traces of Na⁺-dependent pH recovery in Sgk1^flox/flox mice are shown. (B) NHE3 activities in Sgk1^flox/flox villi are presented as the rate of Na⁺-dependent pH change by determining ΔpH_i/Δtime at pH_i 6.5 using typical traces shown in (A). NHE3 activities are shown as mean ± SE. (C) Representative traces of Na⁺-dependent pH recovery in the ileal villi prepared from Sgk1^flox/flox;Villin-Cre mice are shown. (D) NHE3 activities in Sgk1^flox/flox;Villin-Cre villi are presented as the rate of Na⁺-dependent pH change at pH_i 6.5. Stimulation of NHE3-dependent pH recovery is significantly attenuated in Sgk1^flox/flox;Villin-Cre mice compared with Sgk1^flox/flox mice. NHE3 activities at pH_i 6.5 are shown in (E) WT and (F) Nherf2^−/− mice. For all experiments, n = 3–4 mice and 6–8 villi per mouse were used. *, p < 0.01 and **, p < 0.05, compared with the untreated control.