Figure 12.

Patch-clamp analysis of presynaptic IHC function. A, Representative exocytic membrane capacitance changes (ΔC_m, top) and Ca²⁺ currents (I_Ca, bottom) in response to 50 ms depolarization to −14 mV in Clrn1^−/− (gray) and Clrn1^+/+ (black) IHCs. B, Current–voltage relationship for Ca_v1.3 Ba²⁺ currents in control (black, n = 12 IHCs) and mutant (n = 10 IHCs) IHCs. Currents were evoked by 10 ms step depolarizations from a resting potential of −84 mV to variable potentials, and their average of the last 2 ms of current (excluding the tail current) was plotted against the test potential. C, Average ΔC_m responses of control IHCs (7, 8, and 10 IHCs for 20, 50, and 100 ms depolarizations) and mutant IHCs (5, 6, and 8 IHCs for 20, 50, and 100 ms depolarizations) to 50 ms depolarizations to −14 mV. All responses of B and C are given as grand averages (calculated from the means of the individual cells) ± SEM.