Block of sodium conductance and gating current in squid giant axons poisoned with quaternary strychnine

M. D. Cahalan, Wolfhard Almers

Research output: Contribution to journalArticle

54 Citations (Scopus)

Abstract

Quaternary strychnine blocks sodium channels from the axoplasmic side, probably by insertion into the inner channel mouth. Block is strongly voltage dependent, being more pronounced in depolarized than in resting axons. Using potential steps as a means to modulate the level of block, the authors investigate strychnine effects on sodium and gating currents at +50 and -70 mV. They analyze their data in terms of the simplest possible model, wherein only an open channel may receive and retain a strychnine molecule. Their main findings are (a) block by strychnine and inactivation resemble each other and (b) block of sodium and gating currents by strychnine happen with closely similar time-courses. Their data support the hypothesis of Armstrong and Bezanilla (1977) wherein an endogenous blocking particle causes inactivation by inserting itself into the inner mouth of the sodium channel. Quaternary strychnine may act as an artificial substitute for the hypothetical endogenous blocking particle. Further, they suggest that at least 90% of the rapid asymmetrical displacement current in squid axons is sodium channel gating current, inasmuch as quaternary strychnine can block 90% of the displacement current simultaneously with sodium current.

Original languageEnglish (US)
Pages (from-to)57-73
Number of pages17
JournalBiophysical Journal
Volume27
Issue number1
StatePublished - 1979
Externally publishedYes

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Strychnine
Decapodiformes
Axons
Sodium
Sodium Channels
Mouth

ASJC Scopus subject areas

  • Biophysics

Cite this

Block of sodium conductance and gating current in squid giant axons poisoned with quaternary strychnine. / Cahalan, M. D.; Almers, Wolfhard.

In: Biophysical Journal, Vol. 27, No. 1, 1979, p. 57-73.

Research output: Contribution to journalArticle

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