Figure 4
From: Characterization of the honeybee AmNaV1 channel and tools to assess the toxicity of insecticides
Effect of the different regulatory subunits on the biophysical properties of AmNaV1.
(a) The voltage-dependence of activation (G–V). Activation curves were derived from I–V curves (n = 7–14). The I–V curves were obtained using the protocol shown in the inset. The peak current measured at each potential was then divided by (V–Vrev), where V is the test potential and Vrev is the reversal potential. The conductances were then normalized and fitted to a standard Boltzmann equation (see Materials and Methods). (b–c) Plots of the fitted equation activation parameters (V1/2 and kv). Statistical differences were tested using a one-way ANOVA with Bonferroni’s correction. (d) The voltage-dependence of steady-state inactivation. The amplitude of the peak current was plotted as a function of the voltage imposed during the conditioning pulse (n = 8–14) using the protocol in the inset. The data was then fitted to a Boltzmann equation (see Materials and Methods). (e–f) Plots of the inactivation parameters (V1/2 and kv) of the fitted equation. Statistical differences were tested using a one-way ANOVA with Bonferroni’s correction. (g) Time constants of current decay. The protocol in (a) was used to generate transient sodium currents at different voltages. The decay of the transient current was fitted with a single exponential. For each condition, the time constant extracted from the fit was plotted as a function of the voltage imposed (n = 7–14). Typical raw data obtained as a result of a depolarization to −20 mV is shown in the inset to illustrate the different decay kinetics. (h) Recovery from inactivation. The amplitude of the peak current measured during the second pulse was divided by the amplitude measured during the first pulse and was then plotted against the time interval between the pulses (n = 8–14) using the protocol in the inset. (i) The resulting curves were fitted with a single exponential in order to compare the time constants. A statistical analysis using one-way ANOVA with Bonferroni’s correction was performed to assess significant differences between the oocytes expressing regulatory subunits and oocytes expressing AmNaV1 alone. *p < 0.05 and ** and ***p < 0.01 and 0.001.
