Late exercise training improves non-uniformity of transmural myocardial function in rats with ischaemic heart failure.
Cardiovasc Res
; 81(3): 555-64, 2009 Feb 15.
Article
en En
| MEDLINE
| ID: mdl-18703535
ABSTRACT
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 ANDRESULTS:
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 Ca(2+) sensitivity. These alterations were normalized by exercise. Sarcoplasmic reticulum Ca(2+)-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 Ca(2+) homeostasis and myofilament function of cardiomyocytes contribute to this beneficial effect.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Función Ventricular Izquierda
/
Isquemia Miocárdica
/
Remodelación Ventricular
/
Terapia por Ejercicio
/
Insuficiencia Cardíaca
/
Contracción Miocárdica
Tipo de estudio:
Etiology_studies
/
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Cardiovasc Res
Año:
2009
Tipo del documento:
Article
País de afiliación:
Francia