Atrial arrhythmogenicity in aged Scn5a+/ΔKPQ mice modeling long QT type 3 syndrome and its relationship to Na+ channel expression and cardiac conduction

Laila Guzadhur, Sarah M. Pearcey, Rudolf M. Duehmke, Kamalan Jeevaratnam, Anja F. Hohmann, Yanmin Zhang, Andrew A. Grace, Ming Lei, Christopher L H Huang

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Recent studies have reported that human mutations in Nav1.5 predispose to early age onset atrial arrhythmia. The present experiments accordingly assess atrial arrhythmogenicity in aging Scn5a+/ΔKPQ mice modeling long QT3 syndrome in relationship to cardiac Na+ channel, Nav1.5, expression. Atrial electrophysiological properties in isolated Langendorff-perfused hearts from 3- and 12-month-old wild type (WT), and Scn5a+/ΔKPQ mice were assessed using programmed electrical stimulation and their Nav1.5 expression assessed by Western blot. Cardiac conduction properties were assessed electrocardiographically in intact anesthetized animals. Monophasic action potential recordings demonstrated increased atrial arrhythmogenicity specifically in aged Scn5a+/ΔKPQ hearts. These showed greater action potential duration/refractory period ratios but lower atrial Nav1.5 expression levels than aged WT mice. Atrial Nav1.5 levels were higher in young Scn5a+/ΔKPQ than young WT. These levels increased with age in WT but not Scn5a+/ΔKPQ. Both young and aged Scn5a+/ΔKPQ mice showed lower heart rates and longer PR intervals than their WT counterparts. Young Scn5a+/ΔKPQ mice showed longer QT and QTc intervals than young WT. Aged Scn5a+/ΔKPQ showed longer QRS durations than aged WT. PR intervals were prolonged and QT intervals were shortened in young relative to aged WT. In contrast, ECG parameters were similar between young and aged Scn5a+/ΔKPQ. Aged murine Scn5a+/ΔKPQ hearts thus exhibit an increased atrial arrhythmogenicity. The differing Nav1.5 expression and electrocardiographic indicators of slowed cardiac conduction between Scn5a+/ΔKPQ and WT, which show further variations associated with aging, may contribute toward atrial arrhythmia in aged Scn5a+/ΔKPQ hearts. © 2010 The Author(s).
    Original languageEnglish
    Pages (from-to)593-601
    Number of pages8
    JournalPflügers Archiv European Journal of Physiology
    Volume460
    Issue number3
    DOIs
    Publication statusPublished - Aug 2010

    Keywords

    • Age
    • Arrhythmia
    • Atrial arrhythmogenicity
    • Electrophysiology
    • Excitation
    • Genetically modified mice
    • LQT3 syndrome
    • Mouse
    • Na channels
    • Sodium channel

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