Voltage-dependent inhibition of Nav1.4 sodium channels by DCJW and RH-3421. Example traces of Nav1.4 currents in Xenopus oocytes recorded before and after treatment with DCJW at holding potentials of − 120 (A), −60 (B), or −30 mV (C). (D) Slow onset of block by DCJW or RH-3421 at a holding potential of −30 mV. Block was resistant to washout with insecticide-free saline. A 2-s hyperpolarizing pulse to − 120 mV was used to relieve channel inactivation, but not block by SCBIs, prior to the test pulse. Modified and reprinted from Neurotoxicology 81; Silver K, and Soderlund, DM; Action of pyrazoline-type insecticides at neuronal target sites; pp. 136–143; 2005, with permission from Elsevier.