Fig. 8.

Use-dependent lidocaine inhibition of sodium channels in the absence and presence of SCI insecticides. A, effects of 10 μM metaflumizone, RH-4841, or DCJW on the extent of inhibition by lidocaine (200 μM) after 0 to 20 depolarizing prepulses (25 ms) from −120 to −50 mV at 20 Hz. Values were normalized to the mean peak sodium current amplitude measured from the same oocyte before the perfusion of lidocaine. Data points are means ± S.E. of five (lidocaine, metaflumizone + lidocaine, RH-4841 + lidocaine) or four (DCJW + lidocaine) separate experiments with different oocytes; curves were fitted to mean data points using a single-exponential decay function. B, comparison of the extent of resting (after 0 prepulses) and fast-inactivated (after 10 prepulses) sodium channel inhibition by lidocaine in the absence or presence of metaflumizone, RH-4841, or DCJW. Values for use-dependent inhibition marked with an asterisk (*) are significantly (P < 0.05) different from use-dependent inhibition by lidocaine alone.