Representative ICa (upper panel) and Cm (lower panel) in response to a 50 ms depolarizing step to the potential eliciting Imax. (C') Exocytic ∆Cm and corresponding QCa elicited by depolarizations of stimulus durations from 2-100 ms for all respective genotypes and at [Ca2+]e = 6 mM for a second set of recordings from wild-type IHCs to experimentally approximate the decreased ICa observed in the endophilin mutants. (C") Magnification of the initial, short depolarizing steps (2-20 ms) for clarity. Exocytic ∆Cm of cultured endophilin-deficient IHCs appears strongly reduced. (*p < 0.05; **p < 0.01; one-way ANOVA with post-hoc Tukey's or non-parametric K-W with post-hoc Dunn's; please also refer to Appendix Tables S2 and S3 for detailed statistical analysis). The reduced Ca2+-efficiency of exocytosis (∆Cm/QCa) in endophilin-deficient IHCs indicates that diminished Ca2+-influx cannot fully account for the reduction of exocytosis. (*p < 0.05; **p < 0.01; one-way ANOVA with post-hoc Tukey's or non-parametric K-W with post-hoc Dunn's; please also refer to Appendix Table S4 for detailed statistical analysis). 