IHCs from Cx30^Δ/Δ knock-out mice develop normally. A, Potassium currents recorded from mature IHCs (P25) of Cx30^Δ/Δ knock-out mice using the same voltage protocol described in Figure 3. Inset, The presence of I_K,f is evident. B, Current-voltage curves measured from IHCs at 2 ms from the stimulus onset of Cx30^Δ/Δ (n = 6, P25), wild-type (Cx30^+/+: n = 10, P16–P18), and Cx30(−/−) (Cx30^−/−: n = 9, P16–P18) mice. C, Voltage responses recorded from a mature IHC of a Cx30^Δ/Δ mouse, which were elicited by applying hyperpolarizing and depolarizing current injections. Recordings were performed at room temperature.