Time-course of relief of inhibition by A-887826, VX-548, and LTGO-33 at different voltages. (A) Time-course of relief of inhibition by 300 nM A-887826 at +100 mV determined with a single-sweep protocol. Fraction of drug-free channels was assayed by short (3 ms) test steps to +10 mV, each following a 10-ms period at −80 mV to allow recovery from fast inactivation. A succession of depolarizations to +100 mV of various durations produced progressive relief of inhibition by A-887826 (blue trace). The protocol continued with increasing durations of the steps. (B) Channel availability during the test steps to +10 mV as a function of cumulative time when this protocol was applied with depolarizations to +20, +40, and +100 mV (data from a single cell). Data points are fitted with single exponential functions with the indicated time constants. (C) Same for an experiment with 300 nM LTGO-33. (D) Same for an experiment with 1 nM VX-548. (E) Collected data for time constant of relief as a function of voltage for VX-548, A-887826, and LTGO-33, respectively. Mean ± SEM, n = 5, 7, and 17 for VX-548, A-887826, and LTGO-33.