Fig. 5. In vestibular hair cells, Myo1c inhibition modulates the adaptation magnitude but not the hair-bundle creep; however, in the cochlea, Myo1c inhibition has no effect on slow adaptation.

In the utricle, (A) bundle displacements (X) and currents (I) recorded with stimulus waveform (M) using 0.1 mM BAPTA intracellularly with and without 250 μM NMB-ADP in WT and Myo1c^Y61G/Y61G type II utricular hair cells. (B) Summary plots of I_max and current decay properties for steps eliciting ~90% I_max because slow adaptation was more prominent for larger step sizes in vestibular hair cells with fluid-jet stimulation. (C) Mean (solid) ± SD (shaded) of the normalized displacements eliciting ~90% I_max from each experimental condition. (D) Summary plots for properties of the hair-bundle creep show no effect on the mechanical properties of the bundle. In the cochlea, (E) bundle displacements (X) and currents (I) recorded with stimulus waveform (M) using 0.1 mM BAPTA intracellularly with 250 μM NMB-ADP in WT (gray) and Myo1c^Y61G/Y61G (light blue) OHCs. (F) Summary plots show no difference in the percentage of adaptation (P = 0.65), resting open probability (P = 0.64), and peak current (P = 0.76). Percentages of adaptation were calculated for the stimulus eliciting ~50% I_max. Cell examples are marked as diamonds. Black error bars represent mean ± SD. Unpaired, unequal variance Student’s t tests were used. *P ≤ 0.05, **P ≤ 0.01, ****P ≤ 0.0001. For utricle, numbers of cells (animals): Myo1c^Y61G/Y61G, 10 (6); Myo1c^Y61G/Y61G + NMB-ADP, 8 (6); WT, 10 (5); and WT + NMB-ADP, 8 (5). For cochlea, numbers of cells (animals): WT + NMB-ADP, 9 (9); Myo1c^Y61G/Y61G + NMB-ADP, 6 (5).