Figure 1.

Specific Bile acids activate mouse ENaC in Xenopus oocytes. Oocytes were injected with cRNA encoding WT mouse ENaC subunits. Currents were measured the following day using TEVC. A, Oocytes were treated with bile acids (1 mm) for 40 s, followed by 10 μm amiloride. B, the effect of bile acid addition in each experiment was determined as a percentage of the baseline amiloride-sensitive current. The basal amiloride-sensitive current was −3.8 ± 2.8 μA (n = 72). Individual experiments are plotted with the means indicated by a horizontal bar. Each bile acid treatment resulted in a significant change in current (p = 0.002 for CDCA and p < 0.0001 for all others by paired Student's t test). Treatments were compared using a Kruskal–Wallis test followed by Dunn's multiple comparison test: *, p < 0.05; ****, p < 0.0001. C, dose-dependent activation of ENaC by DCA. Top, representative current trace of ENaC activated by successive increasing concentrations of DCA. Bottom, summary of DCA concentration–dependent activation on ENaC, presented as mean ± S.D. (n = 15). Data were fit to the Hill equation using nonlinear regression (logEC₅₀ = −4.1 (78.5 μm) ± 0.26, Hill coefficient = 0.6).