Figure 6. Ca2+ activity in adult cochlear supporting cells.
(A) Live imaging of noise-exposed Sox2Cre-GCaMP6f adult cochlea. Preexposure to 98 dB SPL noise induces ICS wave activity in supporting cells of the adult cochlea, including pillar cells (PC) and Dieters’ cells (DC). Time interval between successive images is 8 seconds. Scale bar: 20 μm. Representative video also shown in Supplemental Video 5. (B and C) Effect of noise exposure on Ca2+ peak and ICS wave activity. Compared with control unexposed cochleae, cochleae from mice exposed to 98 dB as well as 106 dB noise showed increased number of Ca2+ peaks (B) and ICS waves (C) 1 hour after beginning of noise exposure. Twenty-four hours after completion of noise exposure, 98 dB–exposed mice had no significant increase in either Ca2+ peaks or ICS waves compared with control, whereas 106 dB–exposed mice had persistent elevation in both Ca2+ peak activity and ICS waves. (D and E) Effect of noise exposure on Ca2+ peak decay time. Ca2+ peak decay time is compared under the indicated conditions at the individual peak (D) or cochlea (E) level. (F and G) Effect of noise exposure on ICS wave propagation distance. Distance traveled for ICS waves, compared at the individual wave (F) and cochlea (G) level was increased after 106 dB but not 98 dB noise exposure. (B, C, E, and G) Data are shown as mean ± SEM, with individual values in gray. Sample size refers to the number of individual cochleae. (D and F) Tukey plots (box: first quartile/median/third quartile; whiskers: 10th and 90th percentile; dots: individual points outside the whiskers) are shown. Sample size refers to the number of individual cochleae (B, C, E, and G), peaks (D), or waves (F) analyzed. Groups were compared with 1-way ANOVA with Dunnett’s test for multiple comparisons against control for each condition, with P values as indicated underneath each graph. Additionally, 2-tailed unpaired Student’s t test was performed to compare values at the 24-hour time point after noise exposure, as indicated in brackets with associated P values.