© 2003 by European Society of Cardiology
Copyright © 2003, European Society of Cardiology
A novel LQT3 mutation implicates the human cardiac sodium channel domain IVS6 in inactivation kinetics
aDepartment of Medical Physiology, University Medical Center Utrecht, P.O. Box 85060, 3508 AB Utrecht, The Netherlands
bExperimental and Molecular Cardiology Group, AMC Amsterdam, Amsterdam, The Netherlands
cDepartment of Clinical Genetics, UMC Utrecht, Utrecht, The Netherlands
dUniversity Hospital Groningen, Groningen, The Netherlands
eDepartment of Paediatrics, St. Antonius Ziekenhuis, Nieuwegein, The Netherlands
fDepartment of Clinical Genetics, AMC Amsterdam, Amsterdam, The Netherlands
gThe Interuniversity Cardiology Institute of the Netherlands (ICIN), Utrecht, The Netherlands
* Corresponding author. Tel.: +31-30-253-8900; fax: +31-30-253-9036. groenewegen{at}med.uu.nl
* For this manuscript Dr. R.F. Bosch acted as Guest Editor.
The Long QT3 syndrome is associated with mutations in the cardiac sodium channel gene SCN5A. Objective: The aim of the present study was the identification and functional characterization of a mutation in a family with the long QT3 syndrome. Methods: The human cardiac sodium channel gene SCN5A was screened for mutations by single-stranded conformation polymorphism. The functional consequences of mutant sodium channels were characterized after expressing mutant and wild-type cRNAs in Xenopus oocytes by two-electrode voltage clamp measurements. Results: SCN5A screening revealed an A
G substitution at codon 1768, close to the C-terminal end of domain IVS6, which changes an isoleucine to a valine. Functional expression of mutant I1768V-channels in Xenopus oocytes showed that the voltage-dependence and slope factors of activation and inactivation were unchanged compared to wild-type channels. No difference in persistent TTX-sensitive current could be detected between wild-type and I1768V channels, a channel feature often increased in LQT3 mutants. However, I1768V mutant channels recovered faster from inactivation (2.4 times) than wild-type channels and displayed less slow inactivation. Conclusions: We postulate that severe destabilization of the inactivated state leads to increased arrhythmogenesis and QT prolongation in I1768V mutation carriers in the absence of a persistent inward sodium current.
KEYWORDS Biology; Arrhythmia (mechanisms); Long QT syndrome; Na-channel
![]()
CiteULike
Connotea
Del.icio.us What's this?
This article has been cited by other articles:
![]() |
S. Casini, H. L. Tan, Z. A. Bhuiyan, C. R. Bezzina, P. Barnett, E. Cerbai, A. Mugelli, A. A.M. Wilde, and M. W. Veldkamp Characterization of a novel SCN5A mutation associated with Brugada syndrome reveals involvement of DIIIS4-S5 linker in slow inactivation Cardiovasc Res, December 1, 2007; 76(3): 418 - 429. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. Xiong, Y. Z. Farukhi, Y. Tian, D. DiSilvestre, R. A. Li, and G. F. Tomaselli A conserved ring of charge in mammalian Na+ channels: a molecular regulator of the outer pore conformation during slow inactivation J. Physiol., November 1, 2006; 576(3): 739 - 754. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. P.P. Smits, M. W. Veldkamp, C. R. Bezzina, Z. A. Bhuiyan, H. Wedekind, E. Schulze-Bahr, and A. A.M. Wilde Substitution of a conserved alanine in the domain IIIS4-S5 linker of the cardiac sodium channel causes long QT syndrome Cardiovasc Res, August 15, 2005; 67(3): 459 - 466. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. E. Clancy and R. S. Kass Inherited and Acquired Vulnerability to Ventricular Arrhythmias: Cardiac Na+ and K+ Channels Physiol Rev, January 1, 2005; 85(1): 33 - 47. [Abstract] [Full Text] [PDF] |
||||
![]() |
C.-C. Chang, S. Acharfi, M.-H. Wu, F.-T. Chiang, J.-K. Wang, T.-C. Sung, and M. Chahine A novel SCN5A mutation manifests as a malignant form of long QT syndrome with perinatal onset of tachycardia/bradycardia Cardiovasc Res, November 1, 2004; 64(2): 268 - 278. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Pieske, S. R Houser, G. Hasenfuss, and D. M Bers Sodium and the heart: a hidden key factor in cardiac regulation Cardiovasc Res, March 15, 2003; 57(4): 871 - 872. [Full Text] [PDF] |
||||


