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Ca2+ regulatory systems in rat myocardium are altered by 24 weeks treadmill training

  • Cardiovascular System
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Abstract

The present study was conducted to investigate the effects of long-term exercise training on the main components involved in excitation-contraction coupling and relaxation in rat myocardium. Twenty male Wistar rats were divided into sedentary (S) and treadmill-trained (T) groups. Group T was trained for 24 weeks, 5 days/week (25 m/min, 45–60 min, 0% slope). 48 h after the last exercise session, animals were killed and ventricular and soleus muscle homogenates were obtained. The citrate synthase activity in soleus muscle was significantly increased (163%) in T compared with S rats (P<0.01), confirming the exercise training efficacy. Although heart weight and cardiac oxidative capacity were not modified by exercise training, the binding of [3H] ryanodine and the dihydropyridine [3H]PN200-110 to cardiac homogenates, and sarcoplasmic reticulum Ca2+-ATPase activity were increased significantly in the ventricular homogenates from T compared with S animals (P<0.01). Western blot analysis of ventricular homogenates failed to show significant alterations in dihydropyridine receptor and Ca2+-ATPase levels in T animals, but revealed an increase of ryanodine receptor density in this group (P<0.01). The activity of the ectoenzymes 5′-nucleotidase and Mg2+-ATPase was not affected by training (P>0.05). In conclusion, long-term treadmill training induces adaptive changes in some of the components of myocardial rat excitation-contraction coupling and relaxation systems that could contribute to the improvement of cardiac function.

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Acknowledgements

We thank Dr. Alejandro Lucía for critical reading of the manuscript and Luis Felipe Vergas for technical assistance. This study was supported by Grant PB98-0822 from Dirección General de Enseñanza Superior e Investigación Científica (Spain).

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Authors and Affiliations

  1. Department of Biochemistry and Molecular Biology I, Faculty of Biology, Complutense University, 28040, Madrid, Spain

    María Morán, Ana Saborido & Alicia Megías

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  1. María Morán
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  2. Ana Saborido
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  3. Alicia Megías
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Correspondence to Alicia Megías.

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Morán, M., Saborido, A. & Megías, A. Ca2+ regulatory systems in rat myocardium are altered by 24 weeks treadmill training. Pflugers Arch - Eur J Physiol 446, 161–168 (2003). https://doi.org/10.1007/s00424-003-1019-x

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  • DOI: https://doi.org/10.1007/s00424-003-1019-x

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