A novel protocol for assessing exercise performance and dystropathophysiology in the mdx mouse

Authors

  • Andrew B. Rocco BS,

    1. College of Veterinary Medicine, Washington Center for Muscle Biology, Washington State University, Pullman, Washington, USA
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    • The first 2 authors (A.B.R. and J.C.L.) contributed equally to this study.

  • Jewel C. Levalley BS,

    1. School of Molecular Biosciences, Washington Center for Muscle Biology, 135 VBR, Washington State University, Pullman, Washington, USA
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    • The first 2 authors (A.B.R. and J.C.L.) contributed equally to this study.

  • Jennifer A. Eldridge MS,

    1. Department of Animal Sciences, Washington Center for Muscle Biology, Washington State University, Pullman, Washington, USA
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  • Susan A. Marsh PhD,

    1. Nutrition and Exercise Physiology, Washington Center for Muscle Biology, Washington State University, Pullman, Washington, USA
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  • Buel D. Rodgers PhD

    Corresponding author
    1. School of Molecular Biosciences, Washington Center for Muscle Biology, 135 VBR, Washington State University, Pullman, Washington, USA
    2. Department of Animal Sciences, Washington Center for Muscle Biology, Washington State University, Pullman, Washington, USA
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  • These studies were supported by a grant from the Muscular Dystrophy Association (216602 to B.D.R., S.A.M., and the Washington Center for Muscle Biology).

ABSTRACT

Introduction: Dystrophinopathy in the young mdx mouse model of Duchenne muscular dystrophy is comparatively mild, requires induction, and is rarely assessed with tests of systemic muscle function in whole animals. Methods: A modified TREAT-NMD induction protocol was used to evaluate respiratory and exercise performance, starting and ending with maximum oxygen consumption (VO2max) tests. Results: The initial and/or final VO2max, time to exhaustion, speed at exhaustion, and total expended calories were significantly lower in mdx mice. Episodic VO2 and VCO2 fluctuations occurred during training and resulted in dissociated patterns of VO2 and respiratory exchange ratio (RER). These fluctuations further resulted in significantly greater VO2 coefficient of variation and RER values and lower minimal VO2 values. Conclusions: Quantifying respiratory performance during exercise is a potentially useful means for studying pathophysiology in mdx mice, as it assesses intact animals over time, is more sensitive than some histological markers, and assesses systemic muscle function. Muscle Nerve 50: 541–548, 2014

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