title: Pyrethroid modifications of the activation and inactivation kinetics of the sodium channels in squid giant axons.
abstract: The kinetics of sodium channel activation and inactivation were analyzed in the squid giant axons internally treated with various pyrethroids. Pyrethroids increased the steady-state sodium current in squid giant axons by removing the inactivation. The steady-state sodium conductances in control and pyrethroid-treated axons showed the same voltage dependence, indicating that the removal of inactivation by pyrethroids did not lead to an alteration of gating charge transfer. The pyrethroid-modified sodium channels were activated with a biphasic time course involving the movement of at least two gating particles, and both components were voltage-dependent. The slower component was abolished by treatment with either pronase or N-bromoacetamide. The net elementary charges transported in the electric membrane field were reduced in the course of slow activation of the pyrethroid-induced sodium current. It appears that the 'immobilization' of gating charge is related to the slow activation rather than the inactivation of the sodium channel.
authors.affiliation: Department of Pharmacology, Northwestern University Medical School, Chicago, IL 60611.
authors.forename: J R
authors.initials: JR
authors.lastname: de Weille
authors.forename: L D
authors.initials: LD
authors.lastname: Brown
authors.forename: T
authors.initials: T
authors.lastname: Narahashi
mesh_terms: D000818:Animals; D049832:Decapodiformes / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011722:Pyrethrins / Q000494:pharmacology*; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology*; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D011722:Pyrethrins; D015222:Sodium Channels; D013779:Tetrodotoxin