Fig. 6: Reduced MET resting Po and slowed MET currents in Myo7a-ΔC IHCs.
a Illustration of setup with fluid-jet stimulation, patch-clamp electrophysiology, and high-speed imaging with an IHC image (scale bar: 2 µm). b MET responses of IHCs to sinusoidal bundle stimulation. Current shut off during the negative phase of the stimulation (arrowheads) represents the resting current. Resting current divided by maximum MET current estimates resting open probability. c Resting Po decreased (p = 7.5e−5, number of cells (animals); WT: n = 16 (11); Myo7a-∆C: n = 8 (7)) in Myo7a-∆C IHCs. Similar experiments in cochlear basal turn OHCs showed no change in resting Po (p = 0.88, two-tailed, unpaired t-test, WT: n = 12 (7); Myo7a-ΔC: n = 14 (8)). d MET responses of IHCs to step-like force stimulation are shown with the fluid-jet driving voltage waveform (FJ). Largest negative stimuli are shaded lighter. e Current vs displacement plots (activation curves) for the data from d shows the Myo7a-∆C cell is right-shifted. Light-colored traces show curve fits from all cells. f Peak currents showed no change (p = 0.43). g xo in Myo7a-ΔC mice are right-shifted as compared with controls (p = 0.011), consistent with reduced resting Po (p = 6e−4, two-tailed, unpaired t-test). h Regarding the onset, no difference in the displacement rise but a delay in the current onset was found. Steps eliciting ~75% peak current are shown. i For the steps eliciting ~50, ~75, and ~100% peak current, no difference in the motion onset time (time to reach 10% maximum motion, t10%, p = 0.48, two-way ANOVA) but a difference in rise time (time from 10 to 90% maximum motion, t10–90) was found (p = 4.0e−3, two-way ANOVA). j Conversely, current onset time was delayed in Myo7a-ΔC mice by ~0.05 ms (p = 4.4e−6, two-way ANOVA), with no change in current rise time (t10–90, p = 0.24, two-way ANOVA). Summary plots in c, f, g, i, and j are represented as mean ± SD. WT: n = 8 (7), Myo7a-ΔC: n = 6 (6) for panels f, g, i, and j. Data are in the Source Data file.
