Figure 1.
Tonic inhibition by methyl eugenol of Nav1.7 channels. (A, B) Concentration-dependent tonic inhibition by methyl eugenol of Nav1.7 channels in the resting state (holding potential at −120 mV) and inactivated state (holding potential at −60 mV). The current traces of Nav1.7 channels recorded in control conditions and in the presence of varying concentrations of methyl eugenol are superimposed for the resting and inactivated states, respectively. The data are from the same representative cell. The currents were elicited using a 30-ms pulse to 0 mV from a holding potential of −120 mV or −60 mV. (C) Current-voltage relationships in the absence or presence of various concentrations of methyl eugenol were determined by stepping to various depolarized potentials (ranging from −80 to +100 mV in 10 mV increments) for 9 ms from a holding potential of −100 mV. (D) Concentration-response curve for the inhibition of Na+ current by methyl eugenol. The cells were held at −100 mV and stepped to 0 mV for 10 ms. The peak current in the presence of methyl eugenol were normalized to the control peak current, and then averaged. Each point was the mean±SEM of 4–8 cells. The lines represent the best fit for the data to the equation: y=1−xn/(Kdn+xn), where y is the fractional current, Kd is the apparent dissociation constant for methyl eugenol, and n is the Hill coefficient. Kd and n were estimated using a Marquadt nonlinear least-squares procedure.