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BioMed Research International
Volume 2014 (2014), Article ID 704291, 12 pages
Research Article

Cardiac Electrophysiological Alterations in Heart/Muscle-Specific Manganese-Superoxide Dismutase-Deficient Mice: Prevention by a Dietary Antioxidant Polyphenol

1Research Laboratories for Applied Technology of Food, Asahi Group Holdings, Ltd., Moriya, Ibaraki 302-0106, Japan
2Molecular Gerontology, Tokyo Metropolitan Institute of Gerontology, Itabashi-ku, Tokyo 173-0015, Japan
3Department of Advanced Aging Medicine, Chiba University Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan
4Department of Pharmacology, Chiba University Graduate School of Medicine, Chuo-ku, Chiba 260-8670, Japan
5Department of Aging Control Medicine, Juntendo University Graduate School of Medicine, Bunkyo-ku, Tokyo 113-0033, Japan

Received 9 November 2013; Accepted 12 February 2014; Published 19 March 2014

Academic Editor: Y. James Kang

Copyright © 2014 Tadahiro Sunagawa et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Cardiac electrophysiological alterations induced by chronic exposure to reactive oxygen species and protective effects of dietary antioxidant have not been thoroughly examined. We recorded surface electrocardiograms (ECG) and evaluated cellular electrophysiological abnormalities in enzymatically-dissociated left ventricular (LV) myocytes in heart/muscle-specific manganese-superoxide dismutase-deficient (H/M-Sod2−/−) mice, which exhibit dilated cardiomyopathy due to increased oxidative stress. We also investigated the influences of intake of apple polyphenols (AP) containing mainly procyanidins with potent antioxidant activity. The QRS and QT intervals of ECG recorded in H/M-Sod2−/− mice were prolonged. The effective refractory period in the LV myocardium of H/M-Sod2−/− mice was prolonged, and susceptibility to ventricular tachycardia or fibrillation induced by rapid ventricular pacing was increased. Action potential duration in H/M-Sod2−/− LV myocytes was prolonged, and automaticity was enhanced. The density of the inwardly rectifier K+ current () was decreased in the LV cells of H/M-Sod2−/− mice. The AP intake partially improved these electrophysiological alterations and extended the lifespan in H/M-Sod2−/− mice. Thus, chronic exposure of the heart to oxidative stress produces a variety of electrophysiological abnormalities, increased susceptibility to ventricular arrhythmias, and action potential changes associated with the reduced density of . Dietary intake of antioxidant nutrients may prevent oxidative stress-induced electrophysiological disturbances.