Fig. 1.

Recording of gating currents at high bandwidth. (A) Fast- and slow-gating-current components for a pulse from –150 mV HP to 0 mV. The trace is 10 averages at 5 μs per point and 20 kHz, 18.8°C. (B1, a): Patch capacity transient and superimposed exponential fit(τ = 1.9 μs). Pulse from 0 to 10 mV; 10 averages at 0.5 μs per point at open bandwidth (≈350 kHz), 19.0°C; 3 nA calibration. (B1, b) Early-gating-current component and superimposed exponential fit (ON τ = 7.3 μs; OFF τ₁ 5.1 μs and t₂ 65 μs). Pulse from –150 to 50 mV with subtracting pulses from 50 mV SHP to 150 mV; 50 averages at 1 μs per point at 200 kHz, 18.8°C; 200 pA calibration. (B2) Lack of intrinsic gating currents in nonexpressing oocyte. Same recordings conditions as in B1, b. (C) Effect of changing the SHP on early gating currents recorded with a constant pulse from –100 to 0 mV and a constant 100-mV amplitude subtracting pulse; 40 averages at 0.5 μs per point and 200 kHz (10.0°C). The records and the graph show that for SHP more positive than 0 mV, the time integral of the early components reaches maximum steady value (mean ± SE, n = 4).