The effect of exercise training on transverse tubules in normal, remodeled, and reverse remodeled hearts

Kemi, O. J. , Hoydal, M. A., MacQuaide, N. , Haram, P. M., Koch, L. G., Britton, S. L., Ellingsen, O., Smith, G. L. and Wisloff, U. (2011) The effect of exercise training on transverse tubules in normal, remodeled, and reverse remodeled hearts. Journal of Cellular Physiology, 226(9), pp. 2235-2243. (doi: 10.1002/jcp.22559)

Abstract

The response of transverse (T)-tubules to exercise training in health and disease remains unclear. Therefore, we studied the effect of exercise training on the density and spacing of left ventricle cardiomyocyte T-tubules in normal and remodeled hearts that associate with detubulation, by confocal laser scanning microscopy. First, exercise training in normal rats increased cardiomyocyte volume by 16% (P < 0.01), with preserved T-tubule density. Thus, the T-tubules adapted to the physiologic hypertrophy. Next, we studied T-tubules in a rat model of metabolic syndrome with pressure overload-induced concentric left ventricle hypertrophy, evidenced by 15% (P < 0.01) increased cardiomyocyte size. These rats had only 85% (P < 0.01) of the T-tubule density of control rats. Exercise training further increased cardiomyocyte volume by 8% (P < 0.01); half to that in control rats, but the T-tubule density remained unchanged. Finally, post-myocardial infarction heart failure induced severe cardiac pathology, with a 70% (P < 0.01) increased cardiomyocyte volume that included both eccentric and concentric hypertrophy and 55% (P < 0.01) reduced T-tubule density. Exercise training reversed 50% (P < 0.01) of the pathologic hypertrophy, whereas the T-tubule density increased by 40% (P < 0.05) compared to sedentary heart failure, but remained at 60% of normal hearts (P < 0.01). Physiologic hypertrophy associated with conserved T-tubule spacing (similar to 1.8-1.9 mu m), whereas in pathologic hypertrophy, T-tubules appeared disorganized without regular spacing. In conclusion, cardiomyocytes maintain the relative T-tubule density during physiologic hypertrophy and after mild concentric pathologic hypertrophy, whereas after severe pathologic remodeling with a substantial loss of T-tubules; exercise training reverses the remodeling and partly corrects the T-tubule density.

• Item Type: Articles
• Additional Information: The definitive version is available at www3.interscience.wiley.com
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Smith, Professor Godfrey and MacQuaide, Dr Niall and Kemi, Dr Ole
• Authors: Kemi, O. J., Hoydal, M. A., MacQuaide, N., Haram, P. M., Koch, L. G., Britton, S. L., Ellingsen, O., Smith, G. L., and Wisloff, U.
• College/School: College of Medical Veterinary and Life Sciences > School of Cardiovascular & Metabolic Health
• Journal Name: Journal of Cellular Physiology
• Journal Abbr.: J. Cell Physiol.
• Publisher: John Wiley & Sons, Inc.
• ISSN: 0021-9541
• ISSN (Online): 1097-4652
• Published Online: 06 December 2010
• Copyright Holders: Copyright © 2010 Wiley-Liss, Inc
• First Published: First published in Journal of Cellular Physiology 226(9):2235-2243
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher

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