Fig. 2.
Minimal or no block of resting and inactivated Na+ channels by 10 μm bulleyaconitine A (BLA). (A) Superimposed traces of Na+ currents were recorded before and 5 min 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.