A, representative single-channel current recordings obtained at a holding potential of −70 mV from an outside-out patch of an oocyte expressing wild-type (upper trace) or mutant ENaC (lower trace). NaCl or LiCl were present in the bath solution as indicated above the trace by white and grey bars, respectively. B and C, in similar experiments as shown in A single-channel current voltage (I–V) values were obtained at different holding potentials (Vhold) with NaCl or LiCl in the bath solution from outside-out patches of wt (B, n= 4, N= 2) and mutant ENaC (C, n= 6, N= 2)-expressing oocytes. The I–V data were fitted using the Goldman–Hodgkin–Katz equation.