title: Glutathione accelerates sodium channel inactivation in excised rat axonal membrane patches.
abstract: The effects of glutathione were studied on the gating behaviour of sodium channels in membrane patches of rat axons. Depolarizing pulses from -120 to -40 mV elicited sodium currents of up to 500 pA, indicating the simultaneous activation of up to 250 sodium channels. Inactivation of these channels in the excised, inside-out configuration was fitted by two time constants (tau h1 = 0.81 ms; tau h2 = 5.03 ms) and open time histograms at 0 mV revealed a biexponential distribution of channel openings (tau short = 0.28 ms; tau long = 3.68 ms). Both, the slow time constant of inactivation and the long lasting single channel openings disappeared after addition of the reducing agent glutathione (2-5 mM) to the bathing solution. Sodium channels of excised patches with glutathione present on the cytoplasmatic face of the membrane had inactivation kinetics similar to channels recorded in the cell-attached configuration. These observations indicate that redox processes may contribute to the gating of axonal sodium channels.
authors.affiliation: Physiologisches Institut, Universität München, Federal Republic of Germany.
authors.forename: M
authors.initials: M
authors.lastname: Strupp
authors.forename: S
authors.initials: S
authors.lastname: Quasthoff
authors.forename: N
authors.initials: N
authors.lastname: Mitrović
authors.forename: P
authors.initials: P
authors.lastname: Grafe
mesh_terms: D000818:Animals; D001369:Axons / Q000187:drug effects / Q000378:metabolism*; D005978:Glutathione / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008566:Membranes / Q000378:metabolism; D010084:Oxidation-Reduction; D051381:Rats; D011919:Rats, Inbred Strains; D015222:Sodium Channels / Q000187:drug effects*
chemical_list: D015222:Sodium Channels; D005978:Glutathione