Increased late sodium current contributes to long QT-related arrhythmia susceptibility in female mice.
Cardiovasc Res 2012;
95:300-7. [PMID:
22562703 DOI:
10.1093/cvr/cvs160]
[Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
AIMS
Female gender is a risk factor for long QT-related arrhythmias, but the underlying mechanisms remain uncertain. Here, we tested the hypothesis that gender-dependent function of the post-depolarization 'late' sodium current (I(Na-L)) contributes.
METHODS AND RESULTS
Studies were conducted in mice in which the canonical cardiac sodium channel Scn5a locus was disrupted, and expression of human wild-type SCN5A cDNA substituted. Baseline QT intervals were similar in male and female mice, but exposure to the sodium channel opener anemone toxin ATX-II elicited polymorphic ventricular tachycardia in 0/9 males vs. 6/9 females. Ventricular I(Na-L) and action potential durations were increased in myocytes isolated from female mice compared with those from males before and especially after treatment with ATX-II. Further, ATX-II elicited potentially arrhythmogenic early afterdepolarizations in myocytes from 0/5 male mice and 3/5 female mice.
CONCLUSION
These data identify variable late I(Na) as a modulator of gender-dependent arrhythmia susceptibility.
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