Cardiovascular Research Advance Access first published online on August 14, 2008
This version [Corrected Proof] published online on September 12, 2008
Cardiovascular Research, doi:10.1093/cvr/cvn229
Late exercise training improves non-uniformity of transmural myocardial function in rats with ischaemic heart failure
1 INSERM U637, Physiopathologie Cardiovasculaire, CHU Arnaud de Villeneuve, 34295 Montpellier Cedex 5, Montpellier, France
2 Université Montpellier1, UFR de Médecine, F-34295 Montpellier, France
3 EA-4278, Université Avignon et des Pays de Vaucluse, UFR Sciences F-84000, Avignon, France
* Corresponding author. Tel: +33 467 41 52 42; fax: +33 467 41 52 42. E-mail address: olivier.cazorla{at}inserm.fr
Aims: The exercise-induced beneficial mechanisms after long-term myocardial infarction (MI) are incompletely understood. The present study evaluated the effect of treadmill exercise training (5 weeks), started at a late stage of heart failure (HF) (13 weeks post-MI), on rat left ventricle remodelling and dysfunction of the regional global and cellular contractile functions.
Methods and results: In vivo echocardiography confirmed that sub-endocardial (ENDO) layers contract more (+86%) and faster (+50%) than the sub-epicardial (EPI) layers. This gradient was lost in MI rats due to a predominant reduction in the ENDO layer contractility. Exercise partially restored the amplitude and velocity of ENDO contraction, resulting in a partial recovery of the pump function indexed by the aortic blood-flow velocity time integral. At the cellular level, MI impaired ENDO contractile properties by reducing cell shortening (10–7%), calcium transient, and myofilament Ca2+ sensitivity. These alterations were normalized by exercise. Sarcoplasmic reticulum Ca2+-ATPase (SERCA)2a expression and myosin light chain (MLC)-2 phosphorylation in ENDO cells were significantly reduced after MI and were restored by exercise. The EPI layer was only slightly reduced in vivo without cellular alterations.
Conclusion: This study shows that exercise performed at a late stage after MI restored a transmural non-uniformity of myocardium lost during HF. Recoveries of Ca2+ homeostasis and myofilament function of cardiomyocytes contribute to this beneficial effect.
KEYWORDS End-stage heart failure; Myocardial contractility; Contraction; Exercise; Myocardial infarction
Time for primary review: 27 days
This is a new version of this article as the first author's name was incorrect in the running header.
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