The human Nav1.5 F1486 deletion associated with long QT syndrome leads to impaired sodium channel inactivation and reduced lidocaine sensitivity

Weihua Song, Yucheng Xiao, Hanying Chen, Nicole M. Ashpole, Andrew D. Piekarz, Peilin Ma, Andy Hudmon, Theodore Cummins, Weinian Shou

Research output: Contribution to journalArticle

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Abstract

The deletion of phenylalanine 1486 (F1486del) in the human cardiac voltage-gated sodium channel (hNav1.5) is associated with fatal long QT (LQT) syndrome. In this study we determined how F1486del impairs the functional properties of hNav1.5 and alters action potential firing in heterologous expression systems (human embryonic kidney (HEK) 293 cells) and their native cardiomyocyte background. Cells expressing hNav1.5-F1486del exhibited a loss-of-function alteration, reflected by an 80% reduction of peak current density, and several gain-of-function alterations, including reduced channel inactivation, enlarged window current, substantial augmentation of persistent late sodium current and an increase in ramp current. We also observed substantial action potential duration (APD) prolongation and prominent early afterdepolarizations (EADs) in neonatal cardiomyocytes expressing the F1486del channels, as well as in computer simulations of myocyte activity. In addition, lidocaine sensitivity was dramatically reduced, which probably contributed to the poor therapeutic outcome observed in the patient carrying the hNav1.5-F1486del mutation. Therefore, despite the significant reduction in peak current density, the F1486del mutation also leads to substantial gain-of-function alterations that are sufficient to cause APD prolongation and EADs, the predominant characteristic of LQTs. These data demonstrate that hNav1.5 mutations can have complex functional consequences and highlight the importance of identifying the specific molecular defect when evaluating potential treatments for individuals with prolonged QT intervals.

Original languageEnglish
Pages (from-to)5123-5139
Number of pages17
JournalJournal of Physiology
Volume590
Issue number20
DOIs
StatePublished - Oct 2012

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Long QT Syndrome
Sodium Channels
Lidocaine
Action Potentials
Cardiac Myocytes
Mutation
Voltage-Gated Sodium Channels
Architectural Accessibility
Phenylalanine
Computer Simulation
Muscle Cells
Sodium
Kidney
Therapeutics

ASJC Scopus subject areas

  • Physiology

Cite this

The human Nav1.5 F1486 deletion associated with long QT syndrome leads to impaired sodium channel inactivation and reduced lidocaine sensitivity. / Song, Weihua; Xiao, Yucheng; Chen, Hanying; Ashpole, Nicole M.; Piekarz, Andrew D.; Ma, Peilin; Hudmon, Andy; Cummins, Theodore; Shou, Weinian.

In: Journal of Physiology, Vol. 590, No. 20, 10.2012, p. 5123-5139.

Research output: Contribution to journalArticle

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