Figure 4. CDI is greater in mature IHCs than immature IHCs. (A) Top panel, Voltage protocol in which test currents were evoked by pulses (p1, p2) from −84 mV to −20 mV (for ICa) or −30 mV (for IBa) before and after a 200-ms prepulse to various voltages. Bottom panels, representative traces for ICa or IBa recorded in P6–8 or P16–18 mouse IHCs. Currents were evoked by p1 (black) and p2 (red) overlaid for comparison. Scale bars, 0.2 nA (vertical), 2.5 ms (horizontal). (B) Inactivation was measured as the ratio of P2/P1 current amplitude and plotted against prepulse voltage. Results are from mouse IHCs from P6–8 (n = 20 for ICa, n = 6 for IBa) or P16–18 (n = 18 for ICa, n = 8 for IBa). (C) CDI was measured as the difference in p2/p1 for ICa and IBa (FCDI) and is plotted against prepulse voltage for P6–8 and P16–18 IHCs. *p < 0.05 by two-way ANOVA and post-hoc Bonferroni t-test.