Volume 9, Issue 6 pp. 1032-1046

Mitochondrial functional impairment with aging is exaggerated in isolated mitochondria compared to permeabilized myofibers

Martin Picard

Martin Picard

Department of Kinesiology, McGill University, Montreal, QC H2W 1S4, Canada

These authors contributed equally to this work.

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Darmyn Ritchie

Darmyn Ritchie

Muscle & Aging Laboratory, Faculty of Kinesiology and Faculty of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada

These authors contributed equally to this work.

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Kathryn J. Wright

Kathryn J. Wright

Muscle & Aging Laboratory, Faculty of Kinesiology and Faculty of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada

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Caroline Romestaing

Caroline Romestaing

Laboratoire de Physiologie Intégrative, Cellulaire et Moléculaire, Université de Lyon, Lyon, France

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Melissa M. Thomas

Melissa M. Thomas

Muscle & Aging Laboratory, Faculty of Kinesiology and Faculty of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada

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Sharon L. Rowan

Sharon L. Rowan

Muscle & Aging Laboratory, Faculty of Kinesiology and Faculty of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada

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Tanja Taivassalo

Tanja Taivassalo

Department of Kinesiology, McGill University, Montreal, QC H2W 1S4, Canada

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Russell T. Hepple

Russell T. Hepple

Muscle & Aging Laboratory, Faculty of Kinesiology and Faculty of Medicine, University of Calgary, Calgary, AB T2N 1N4, Canada

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First published: 17 September 2010
Citations: 193
Russell T. Hepple, Faculty of Kinesiology, University of Calgary, 2500 University Dr NW, Calgary, AB T2N 1N4, Canada. Tel.: 403 220 8549; fax: 403 284 3553; e-mail: [email protected]

Summary

Mitochondria regulate cellular bioenergetics and apoptosis and have been implicated in aging. However, it remains unclear whether age-related loss of muscle mass, known as sarcopenia, is associated with abnormal mitochondrial function. Two technically different approaches have mainly been used to measure mitochondrial function: isolated mitochondria and permeabilized myofiber bundles, but the reliability of these measures in the context of sarcopenia has not been systematically assessed before. A key difference between these approaches is that contrary to isolated mitochondria, permeabilized bundles contain the totality of fiber mitochondria where normal mitochondrial morphology and intracellular interactions are preserved. Using the gastrocnemius muscle from young adult and senescent rats, we show marked effects of aging on three primary indices of mitochondrial function (respiration, H2O2 emission, sensitivity of permeability transition pore to Ca2+) when measured in isolated mitochondria, but to a much lesser degree when measured in permeabilized bundles. Our results clearly demonstrate that mitochondrial isolation procedures typically employed to study aged muscles expose functional impairments not seen in situ. We conclude that aging is associated with more modest changes in mitochondrial function in sarcopenic muscle than suggested previously from isolated organelle studies.

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