Figure 9.

The relatively slow times of activation and deactivation for mENaC containing αI93C substitution enables documentation at the single-channel level of voltage-dependent gating for a substitution similar to PHA-1-causing mutations. (A) Four representative single-channel current traces in outside-out patches held at 60 (left) and −60 mV (right) for mutant mENaC harboring the αI93C substitution. The displayed currents immediately follow changes in holding potential. The bath and pipette [Li⁺] were symmetrical for these experiments. Inward Na⁺ current is downward; C, closed state. (B) Dairy plot showing changes in instantaneous (2 s bins), mean NP_o for αI93C channels as they deactivate immediately after a voltage step from −60 to 60 mV. Data were obtained from n ≥ 4 experiments identical to those shown in panel A.