Effects of charybdotoxin on K+ channel (Kv1.2) deactivation and inactivation kinetics

Leslie K. Sprunger, Nancy J. Stewig, Scott M. O'Grady

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19 Scopus citations


Of particular interest for voltage-gated K+ channels are the effects of membrane voltage and pharmacologic agents on channel kinetics. We have characterized in detail properties of a Kv1.2 channel expressed in oocytes as the basis for investigation of its structure-function relationships. This channel exhibited a voltage-dependent rate of activation with a V( 1/4 ) of -21 mV. Voltage-dependent steady-state inactivation overlapped the activation curve with half-maximal inactivation occurring at -22 mV. Dendrotoxin inhibited channel activation with an IC50 of 8.6 nM at +35 mV. Charybdotoxin also blocked this K+ channel (IC50 = 5.6 nM). While dendrotoxin block was not affected by channel activation, charybdotoxin exhibited additional accumulation of block following activation, which was relieved with a time constant of 0.5 s upon repolarization of the membrane. The deactivation of this channel was accelerated in the presence of charybdotoxin while not significantly affected by dendrotoxin.

Original languageEnglish (US)
Pages (from-to)357-364
Number of pages8
JournalEuropean Journal of Pharmacology
Issue number3
StatePublished - Oct 31 1996

Bibliographical note

Copyright 2007 Elsevier B.V., All rights reserved.


  • Channel kinetics
  • Charybdotoxin
  • Deactivation
  • Dendrotoxin
  • Inactivation
  • Voltage dependence


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