Potential-dependent interaction of toxin from venom of the scorpion Buthus eupeus with sodium channels in myelinated fibre. Voltage clamp experiments

G. N. Mozhayeva, A. P. Naumov, E. D. Nosyreva, E. V. Grishin

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Abstract

1. 1. The steady-state characteristics of the sodium channel gating in the nodal membrane were determined under voltage clamp conditions before and after treatment with toxins from the venom of scorpion, Buthus eupeus. 2. 2. The apparent binding constant (KA) of the toxin was determined for different levels of the membrane potential. At potentials more negative than -120 mV, KA tends to a constant level. KA is maximum at about -80 mV, and it decreases as the potential is reduced to 0 mV. 3. 3. A model assuming that the voltage dependency of KA is mainly due to the difference in electrical energy between inactivated states of normal and poisoned channels is proposed. An additional decrease in overall binding of toxin results from the transition of a fraction of the sodium channels into the state of slow inactivation.

Original languageEnglish (US)
Pages (from-to)587-602
Number of pages16
JournalBBA - Biomembranes
Volume597
Issue number3
DOIs
StatePublished - Apr 24 1980

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Keywords

  • (Nodal membrane)
  • Binding constant
  • Na channel
  • Scorpion toxin
  • Voltage clamp

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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