Figure 7.

Na⁺-sensitive outward K⁺ currents are absent in spiral ganglion neurons (SGNs) isolated from K_Na1 DKO mice. Whole cell patch clamp recordings were performed on SGNs isolated from the basal one-third of the cochlea from 6-week-old WT and DKO mice. (A) Whole-cell currents revealed a transient inward current and also outward currents in SGNs isolated from both WT and DKO mice in response to varying depolarization from a holding potential of −80 mV to 60 mV in 10-mV increments (control). Bath application of 1 µM TTX completely blocked voltage-sensitive inward currents in SGNs isolated from both WT and DKO mice (+TTX). The difference current generated by subtraction of currents recorded in the presence of TTX from those recorded before TTX application (control) revealed the TTX-sensitive outward currents in SGNs isolated from WT and DKO mice (difference, TTX-sensitive). (B) To compare findings across SGNs, the current density-voltage relationship was generated using the steady state K⁺ current amplitude for both WT and DKO mice. (C) The mean TTX-sensitive outward K⁺ current density calculated at 0 mV was significantly greater in SGNs from WT compared to DKO mice. Data are plotted to show individual replicates (animals) and mean ± SEM. Values (mean ± SEM) and statistical analyses are provided in the Results.