Figure 7.

Effects of erg channel blockers on the currents in type I cells at different ages. A, In a P2 cell, 10 μm E-4031 blocked g_max 32%, the largest effect seen in young cells. Bottom, Tail current activation curves for the data traces shown above and other traces from the same experiment that were omitted for clarity. V_1/2, S, and g_max values are as follows: Control, −31 mV, 5.9 mV, 42 nS; E-4031-sensitive, −34 mV, 6.1 mV, 12 nS; E-4031-insensitive, −27 mV, 7.3 mV, 29 nS. B, In a P16 cell, 10 μm E-4031 blocked g_HP 98% and the maximum tail current by 33%. The control activation curve (from tail currents) was best fit with the sum of two Boltzmann functions: V₁ of −82 mV, S₁ of 5.0 mV, g_max1 of 101 nS, V₂ of −64 mV, S₂ of 3.0 mV; g_max2 of 48 nS. The tail current activation curves for the E-4031-sensitive and E-4031-insensitive currents were fit with single Boltzmann functions with values similar to those of the two Boltzmann functions summed in the control curve; V_1/2, S, and g_max values of −83 mV, 4.3 mV, and 94 nS and −63 mV, 1.9 mV, and 95 nS, respectively. C, In a P18 type I hair cell with a very large negative conductance, 10 μm WAY-123,398 reversibly blocked g_HP by 97% (D). E, The WAY-123,398-insensitive current had an activation curve with V_1/2, S, and g_max values of −46 mV, 7.1 mV, and 69 nS.