Rapid and slow gating of veratridine-modified sodium channels in frog myelinated nerve.
The properties of voltage-dependent Na channels modified by veratridine (VTD) were studied in voltage-clamped nodes of Ranvier of the frog Rana pipiens. Two modes of gating of VTD-modified channels are described. The first, occurring on a time scale of milliseconds, is shown to be the transition of channels between a modified resting state and a modified open state. There are important qualitative and quantitative differences of this gating process in nerve compared with that in muscle (Leibowitz et al., 1986). A second gating process occurring on a time scale of seconds, was originally described as a modified activation process (Ulbricht, 1969). This process is further analyzed here, and a model is presented in which the slow process represents the gating of VTD-modified channels between open and inactivated states. An expanded model is a step in the direction of unifying the known rapid and slow physiologic processes of Na channels modified by VTD and related alkaloid neurotoxins.
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Department of Anesthesia Research Laboratories, Brigham and Women's Hospital, Boston, Massachusetts.
D000818:Animals; D004594:Electrophysiology; D066298:In Vitro Techniques; D011894:Rana pipiens; D011901:Ranvier's Nodes / Q000187:drug effects / Q000502:physiology*; D012584:Sciatic Nerve / Q000187:drug effects / Q000502:physiology*; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology*; D014701:Veratridine / Q000494:pharmacology*; D014702:Veratrine / Q000031:analogs & derivatives*
D015222:Sodium Channels; D014701:Veratridine; D014702:Veratrine