Figure 4.

Whole-cell Ca²⁺ currents in SGNs resistant to a mixture of L-type, N-type, P/Q-type, and R-type current blockers and mibefradil-sensitive currents. A mixture of 10 μm nimodipine, 1 μm ATX, 1 μm CTX, and 200 nm rSNX-482 was used. A, Current traces recorded using a holding voltage of −70 to a step voltage of 0 mV in apical neurons (control current trace, black; after application of blocker mixture, blue). B, Similar data obtained from basal neurons as described by A. The corresponding current density–voltage relations for apical (A) and basal (B) neurons (n = 7). The mixture blocked 81.6 ± 7.8% (n = 7) of the total Ca²⁺ currents in apical neurons. Meanwhile, 71.1 ± 6.2% (n = 7) of the total Ca²⁺ currents were blocked in basal neurons. C, Ca²⁺ current traces from a basal SGN held at a holding potential of −90 mV and stepped to −10 mV. The control trace (black) and the residual current after application of 5 μm mibefradil (blue) are shown. The difference current or the mibefradil-sensitive current shows a transient profile, consistent with T-type Ca²⁺ currents (red). The corresponding current–voltage relations are shown from data from four basal SGNs.