Fig. 5. Development of and recovery from prenylamine block of inactivated sodium channels. For the development of inactivated-state block, the prepulse duration at −70 mV was varied, and the peak current at the test pulse was measured, normalized to the initial peak amplitude (t = 0), and then plotted against the prepulse duration (A ). The data for 3 μm prenylamine were well fitted by a double-exponential function. For recovery from the inactivated-state block, the interpulse duration at −140 mV was varied, and the peak current at the test pulse was measured, normalized with respect to the peak amplitude without the prepulses, and plotted against the interpulse duration (B ). The data were well fitted by a double-exponential function.