Purified ciguatoxin-induced modifications in excitability of myelinated nerve fibre.
The effects of external applications of 0.22-1.12 nM of purified ciguatoxin (CTX-1B), extracted from the moray-eel, were studied on frog current and voltage clamped node of Ranvier. CTX-1B induced spontaneous action potentials at a frequency of 70-100 Hz, suppressed by 50 microM lidocaine, which resulted from a toxin-induced maintained (late) inward Na current representing about 5.5% of peak Na current. Peak and late currents showed different voltage characteristics but were similarly affected by 50-500 microM lidocaine. It is concluded that the effects of CTX-1B are qualitatively but not quantitatively similar to those previously studied of partially purified toxin (2).
Benoit
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Laboratoire de Physiologie cellulaire, URA CNRS 1121, Université Paris-Sud, Orsay, France.
Legrand
A M
AM
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002922:Ciguatoxins / Q000494:pharmacology*; D004524:Eels; D008012:Lidocaine / Q000494:pharmacology; D009413:Nerve Fibers, Myelinated / Q000502:physiology*; D011893:Rana esculenta; D015222:Sodium Channels / Q000187:drug effects / Q000502:physiology
D015222:Sodium Channels; D002922:Ciguatoxins; D008012:Lidocaine