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Block of wild-type and inactivation-deficient cardiac sodium channels IFM/QQQ stably expressed in mammalian cells.

Publication ,  Journal Article
Grant, AO; Chandra, R; Keller, C; Carboni, M; Starmer, CF
Published in: Biophys J
December 2000

The role of inactivation as a central mechanism in blockade of the cardiac Na(+) channel by antiarrhythmic drugs remains uncertain. We have used whole-cell and single channel recordings to examine the block of wild-type and inactivation-deficient mutant cardiac Na(+) channels, IFM/QQQ, stably expressed in HEK-293 cells. We studied the open-channel blockers disopyramide and flecainide, and the lidocaine derivative RAD-243. All three drugs blocked the wild-type Na(+) channel in a use-dependent manner. There was no use-dependent block of IFM/QQQ mutant channels with trains of 20 40-ms pulses at 150-ms interpulse intervals during disopyramide exposure. Flecainide and RAD-243 retained their use-dependent blocking action and accelerated macroscopic current relaxation. All three drugs reduced the mean open time of single channels and increased the probability of their failure to open. From the abbreviation of the mean open times, we estimated association rates of approximately 10(6)/M/s for the three drugs. Reducing the burst duration contributed to the acceleration of macroscopic current relaxation during exposure to flecainide and RAD-243. The qualitative differences in use-dependent block appear to be the result of differences in drug dissociation rate. The inactivation gate may play a trapping role during exposure to some sodium channel blocking drugs.

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Published In

Biophys J

DOI

ISSN

0006-3495

Publication Date

December 2000

Volume

79

Issue

6

Start / End Page

3019 / 3035

Location

United States

Related Subject Headings

  • Transfection
  • Sodium Channels
  • Sodium Channel Blockers
  • Recombinant Proteins
  • Myocardium
  • Models, Biological
  • Membrane Potentials
  • Lidocaine
  • Humans
  • Heart
 

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Grant, A. O., Chandra, R., Keller, C., Carboni, M., & Starmer, C. F. (2000). Block of wild-type and inactivation-deficient cardiac sodium channels IFM/QQQ stably expressed in mammalian cells. Biophys J, 79(6), 3019–3035. https://doi.org/10.1016/S0006-3495(00)76538-6
Grant, A. O., R. Chandra, C. Keller, M. Carboni, and C. F. Starmer. “Block of wild-type and inactivation-deficient cardiac sodium channels IFM/QQQ stably expressed in mammalian cells.Biophys J 79, no. 6 (December 2000): 3019–35. https://doi.org/10.1016/S0006-3495(00)76538-6.
Grant AO, Chandra R, Keller C, Carboni M, Starmer CF. Block of wild-type and inactivation-deficient cardiac sodium channels IFM/QQQ stably expressed in mammalian cells. Biophys J. 2000 Dec;79(6):3019–35.
Grant, A. O., et al. “Block of wild-type and inactivation-deficient cardiac sodium channels IFM/QQQ stably expressed in mammalian cells.Biophys J, vol. 79, no. 6, Dec. 2000, pp. 3019–35. Pubmed, doi:10.1016/S0006-3495(00)76538-6.
Grant AO, Chandra R, Keller C, Carboni M, Starmer CF. Block of wild-type and inactivation-deficient cardiac sodium channels IFM/QQQ stably expressed in mammalian cells. Biophys J. 2000 Dec;79(6):3019–3035.
Journal cover image

Published In

Biophys J

DOI

ISSN

0006-3495

Publication Date

December 2000

Volume

79

Issue

6

Start / End Page

3019 / 3035

Location

United States

Related Subject Headings

  • Transfection
  • Sodium Channels
  • Sodium Channel Blockers
  • Recombinant Proteins
  • Myocardium
  • Models, Biological
  • Membrane Potentials
  • Lidocaine
  • Humans
  • Heart