Figure 3.

K_V1.8^−/− type II HCs in all zones of the sensory epithelium lacked the major rapidly inactivating conductance, g_A, and had less delayed rectifier conductance. Activation and inactivation varied with epithelial zone and genotype. (A) g_A inactivation time course varied across zones. (A.1) Zones of the utricular epithelium. (A.2) Normalized currents evoked by steps from −124 mV to +30 mV with overlaid fits of Eq. 3. (A.3) τ_Inact,Fast was faster in K_V1.8^+/− than K_V1.8^+/+ HCs, and faster in LES than other zones. Brackets show post hoc pairwise comparisons between two zones (vertical brackets) and horizontal brackets compare two genotypes; see Table 3 for statistics. (A.4) Fast inactivation was a greater fraction of total inactivation in LES than striola.

(B) Exemplars; ages, left to right, P312, P53, P287, P49, P40, P154.

(C) % inactivation at 30 mV was much lower in K_V1.8^−/− than K_V1.8^+/− and K_V1.8^+/+, and lower in striola than LES and MES. Interaction between zone and genotype was significant (Table 3).

(D) Exemplar currents and G-V curves from LES type II HCs show a copy number effect. (D.1) Currents for examples of the 3 genotypes evoked by steps from −124 mV to +30 mV fit with Eq. 3. (D.2) Averaged peak and steady-state conductance-voltage datapoints from LES cells (+/+, n=37; −/−, n=20) were fit with Boltzmann equations (Eq. 1) and normalized by g_max in (D.3). See Table 4 for statistics.