Navsubtype selectivity of H4.A–H, representative current traces before (black) and after (red) addition of H4. H4 at 100 nM inhibited rNav1.2, rNav1.3, mNav1.6, and hNav1.7; 10 μM H4 modestly inhibited rNav1.8 but had no effect on rNav1.4, hNav1.5, and hNav1.9. I, concentration–response curves of H4 at rNav1.2, rNav1.3, mNav1.6, and hNav1.7 assessed by whole-cell patch-clamp experiments. Data are mean ± SD, with n = 3 to 6 cells per data point.