Figure 2. Minimal or no block of resting and inactivated Na⁺ channels by 10 μM BLA.

(A) Superimposed traces of Na⁺ currents were recorded before and 5 minutes after application of 10 μM BLA. For the resting block by BLA, the cell was held at −140 mV and stimulated once every 30 s by a brief test pulse (+50 mV for 3 ms; inset). (B) For the inactivated block by BLA, the cell was depolarized to −70 mV for 10 s (inset), which provided sufficient time for inactivated Na⁺ channels to interact with BLA. Superimposed traces of Na⁺ currents before and after application of 10 μM BLA were recorded by a brief test pulse. An interpulse (−140 mV for 100 ms; inset), which allowed drug-free inactivated Na⁺ channels to recover, was applied before the brief test pulse. Again, the inactivated block by BLA was minimal.