FIGURE 6.

Effects of DHS and depolarization on the hair-bundle mechanics. (A, upper) IHC, with MT current scaled to its maximum value, I_MAX, plotted against displacement in control saline (solid circles, prior control) and in saline containing 0.2 mM DHS (crosses). (A, lower) Force-displacement relationships, with symbols the same as in A, upper. The current-displacement relationships have been fitted with single Boltzmann functions (see Methods), with I_MAX = 655 pA (control) and 40 pA (DHS). Note that the DHS plot is shifted negative, which is consistent with a reduction in resting intracellular calcium due to channel block. K_HB = 3.4 mN·m⁻¹ in control and 4.9 mN·m⁻¹ in DHS. P11 rat. (B, upper) OHC, with MT current scaled to its maximum value, I_MAX, plotted against displacement in control saline. I_MAX = 430 pA. (B, lower) Force-displacement relationships in control (solid circles) and in 0.2 mM DHS (crosses). The MT current in DHS was too small to be plotted. K_HB = 4.2 mN·m⁻¹ in control and 14.4 mN·m⁻¹ in DHS. P11 rat. (C, upper) OHC, with MT current scaled to its maximum value, I_MAX, plotted against displacement at −84 mV holding potential (solid circles) and at +106 mV (crosses). (C, lower) Force-displacement relationships with symbols the same as in C, upper. I_MAX and K_HB = 560 pA and 1.7 mN·m⁻¹, respectively, at −84 mV, and 610 pA and 3.6 mN·m⁻¹, respectively, at +106 mV. P11 rat. Stiffness of flexible fiber for all three cells, 1.6 mN·m⁻¹.