Figure 4.

Voltage-dependence of the gating charge recovery and channel closure in the inactivated Kv1.5 NCM channels. (A–C) Superimposed gating current traces were elicited by a double pulse to 60 mV separated by a variable interpulse interval (protocol above each record). The duration of both prepulse and the test pulse was 12 ms and the interval between pairs of pulses was 2 s at –80 mV, 10 s at −60 mV and 15 s at −40 mV, respectively. Currents were recorded with symmetrical 135 mM NMG⁺ _i/o solutions. Solid lines are the best fits to the peak of on-gating currents using a single exponential function with time constants (τ) shown on tracings. (D–F) After a 12-ms pulse to 60 mV, Na⁺ tail currents were recorded at −80, −60, and −40 mV, respectively. Voltage protocol is shown above each record. The current was recorded with 135 mM NMG⁺ _i/135 mM Na⁺ _o solutions. The tail currents were fitted by double exponential functions with time constants (τ₁ and τ₂) shown on tracings. Dotted lines represent zero current level.