The native Kv3.4 channel expressed in DRG neurons undergoes strict OSI. Currents were recorded under cell-attached patch-clamping conditions (Materials and methods). Details of A–F are as described in the Fig. 5 legend. For comparison, the red symbol in C indicates the time constant determined from the double-pulse protocol. The conditioning pulse in D activated 16% of the peak conductance. The complex steady-state inactivation curve reflects the complexity of the native system including a dominant Kv3.4 component and two minor components corresponding to a low voltage–activated A-type K⁺ current described previously and a sustained outward current (Ritter et al., 2012). The best-fit parameters describing the small voltage-dependent component of the double Boltzmann were V_1/2 = −98 mV and k = 3 mV. The solid red line in E represents the following empirical best-fit sum of exponential terms: I/I₀ (t) = 0.79 − 0.16(1 − e^−t/16)³ + 0.2e^−t/177.