Figure 4: Effect of rAe1a on BgNav1 and hNaV1.5.
Left panels: Representative traces showing the effect of rAe1a (200 nM) on sodium currents mediated by (A) BgNaV1, (C) mutant BgNaV1 (H805Y/D812E), and (E) hNaV1.5 heterologously expressed in Xenopus oocytes. Currents were evoked by a depolarization to −15 mV, with black and red traces corresponding to the current before and after toxin application, respectively. Right panels: Effect of 200 nM rAe1a on normalized conductance-voltage (G–V) relationships (G/Gmax) and steady-state inactivation (SSI) relationships (I/Imax) for (B) BgNaV1, (D) mutant BgNaV1, and (F) hNaV1.5. G/Gmax and I/Imax are shown by closed and open circles respectively, before (black) and after (red) toxin addition. Normalization was performed relative to the peak current before toxin addition. Oocytes were depolarized by steps of 5 mV from a holding potential of −90 mV up to 5 mV for 50 ms, followed by a depolarizing pulse to −15 mV for 50 ms. Peak current from the initial step series was converted to conductance and normalized to obtain the G-V relationship while peak current from the following −15 mV voltage depolarization step was normalized to yield the SSI relationship. rAe1a inhibited the mutant BgNaV1 channel to a lesser extent than wild-type BgNaV1, and it had no effect on the human NaV1.5 channel. Data points are mean ± SEM, and n = 3–5 for all experiments shown.
