FIG. 1.

Allethrin-sensitive currents are mediated by VGCCs in differentiated PC12 cells. (A and B) A large inward current was induced during a ramp depolarization from −100 to 60 mV from a holding potential of −80 mV. (A) The amplitude of this current was increased by addition of 5 or 20μM AL. (B) Increased current was observed in the presence of 0.5μM TTX and abolished by 100μM Cd²⁺, a nonspecific VGCC blocker. Control trace (no TTX or AL) is nearly identical to the TTX trace. This indicates that the AL-increased current is mediated by VGCCs. The scale in (A) also represents (B) vertical = 150 pA, horizontal = 20 ms. Stimulus protocol for (A) and (B) is shown beneath scale bars in (A) (not in scale). (C and F) Whole-cell currents of VGCCs in PC12 cells were evoked by stepping a 200-ms depolarizing pulse to 0 mV from a holding potential of −70 mV. (C) Traces were recorded before and during incubation with 5μM AL. Subtraction of control from treated results in AL-stimulated current. Peak, end, and tail currents are labeled for reference. (D) Magnified view of control and 5μM AL tail current from (C). (E) Traces recorded before and during incubation with 5μM AL in the presence of 0.5μM TTX. (F) Magnified view of TTX and TTX + 5μM AL tail current from (E). The scale in (C) and (E) is horizontal = 10 ms, vertical = 100 pA; for (D) and (F): horizontal = 4 ms, vertical = 100 pA.