Effect of ProTx-I on native Nav1.9 currents in rat DRG neurons. (A) Enhancement by 100 nM ProTx-I of rNav1.9-mediated current evoked by same protocol as in Fig. 7 A. (B) Peak conductance versus test voltage before and after 100 nM ProTx-I (different cell than A). Closed symbols, peak conductance calculated from peak current using a reversal potential of +50 mV; smooth curves, best fits to a Boltzmann function, as in Fig. 7 B. Control: G_max = 70 nS, V_1/2 = −35 mV, and k = 5.0 mV. 100nm ProTx-I: G_max = 49 nS, V_1/2 = −44 mV, and k = 6.0 mV. (C) Voltage dependence of inactivation determined using a test pulse to −50 mV from a variety of holding potentials established for 2 s as in Fig. 7 C. Smooth curves are best fits to Boltzmann functions. Control: V_1/2 = −41 mV and k = 6.2 mV. 100 nM ProTx-I: V_1/2 = −47 mV and k = 5.6 mV. All solutions contained 300 nM TTX to block TTX-s Nav channels.