LA block enhances the rate of NaChBac inactivation. (A–C) Rates of NaChBac inactivation (1/τ) were plotted against drug concentration for lidocaine (A), ranolazine (B), and benzocaine (C). The insets in each plot are normalized traces illustrating the increased inactivation rates when the channel is blocked. n = 4. (D) The three- and four-state models used to fit the increase in inactivation rate where O is the open channel, B is the channel when occupied by the blocker, and I is the inactivated state. The three-state model adequately fit the data for lidocaine and ranolazine, whereas for benzocaine the addition of an extra blocking state, BS2, from which inactivation was promoted (solid line fit in C), improved the fit at lower concentrations when compared with the three-state model (dashed line shown for comparison in C). Error bars represent SEM.