Intracellular GTPγS potentiates NaV1.9 activity. (A) Averaged whole-cell currents recorded from NaV1.9-expressing cells in the absence (control) or presence (+GTPγS) of 200 µM intracellular GTPγS. (B) Mean current-voltage relationships measured with control intracellular solution (n = 33) or with internal GTPγS at 20 µM (n = 9), 63 µM (n = 9), or 200 µM (n = 21). (C) Mean current density measured at −40 mV with control pipette or pipette plus GTPγS at 20 µM (n = 9), 63 µM (n = 9), or 200 µM (n = 21). (D) Whole-cell currents measured at −40 mV after rupture of membrane patch from cells dialyzed with 200 µM of intracellular GTPγS and normalized to the mean whole-cell current measured in cells dialyzed with control pipette solution (n = 8). (E) Superimposed steady-state channel availability (open circles) and conductance-voltage relationship (closed circles) recorded in the presence of intracellular GTPγS (n = 8 and 20, respectively). Dotted lines illustrate activation and inactivation curves determined in control solution (from Fig. 2 E). (F) Time course of recovery from fast inactivation (n = 8). Solid line represents data fitted with a two-exponential function. Dotted line depicts the recovery from inactivation recorded using control intracellular solution (from Fig. 2 F). Data are represented as means ± standard error of the mean.
