Voltage dependence of open-channel block. (A) Normalized peak resurgent current versus conditioning pulse duration for cerebellar nuclear neurons. Data from Purkinje cells are reproduced for comparison. Data are fitted with single exponentials, with parameters given in Results. For the +30-mV step, N = 5; for the 0-mV step, N = 6. (B) Voltage protocol and representative traces to measure the voltage dependence of block. (C) Resurgent current normalized to the resurgent current evoked after a step to +50 mV and fitted with a straight line for WT Purkinje cells (N = 8), WT nuclear cells (N = 6), and med Purkinje cells (N = 9).