Effect of external acidification on leak currents in WT and V876E fibers. (A) Membrane currents evoked by a voltage ramp applied from a holding potential of 0 mV at an external pH of 7.2 and 6, and current difference between pH 6.0 and 7.2 in the same V876E fiber. (B) Means and SEM of current differences between pH 6.0 and pH 7.2 in WT and V876E fibers. The number of data points has been reduced for clarity.