Figure 3.

Reduced exocytosis in the basal IHCs of BDNF^Pax2 KO mice. A, B, I_Ca and ΔC_m responses from adult basal turn control and BDNF^Pax2 KO IHCs. Recordings were obtained in response to 100 ms voltage steps, in 10 mV increments, from the holding potential of −81 mV. For clarity, only maximal responses are shown in A. C, The relation between Ca²⁺ entry and exocytosis in IHCs, estimated using a synaptic transfer function, was obtained by plotting ΔC_m against the peak I_Ca for voltage steps from −71 mV to that where the maximal I_Ca occurred from the I-V curves shown in B. Data were approximated using a power function: ΔC_m ∝ I_Ca^N, where N is the power. N was 1.3 ± 0.1 (n = 5) in control and 1.1 ± 0.1 (n = 4) in BDNF^Pax2 KO mice. D, Ca²⁺ currents and changes in cell membrane capacitance from apical (ap) and basal (ba) IHCs.