The dose-related response of rabbit fast muscle to long-term low-frequency stimulation

Authors

  • Hazel Sutherland BSc,

    Corresponding author
    1. British Heart Foundation Skeletal Muscle Assist Research Group, Department of Human Anatomy and Cell Biology, University of Liverpool, Liverpool L69 3GE, UK
    • British Heart Foundation Skeletal Muscle Assist Research Group, Department of Human Anatomy and Cell Biology, University of Liverpool, Liverpool L69 3GE, UK
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  • Jonathan C. Jarvis PhD,

    1. British Heart Foundation Skeletal Muscle Assist Research Group, Department of Human Anatomy and Cell Biology, University of Liverpool, Liverpool L69 3GE, UK
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  • Martin M. N. Kwende PhD,

    1. British Heart Foundation Skeletal Muscle Assist Research Group, Department of Human Anatomy and Cell Biology, University of Liverpool, Liverpool L69 3GE, UK
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  • Stephen J. Gilroy BSc,

    1. British Heart Foundation Skeletal Muscle Assist Research Group, Department of Human Anatomy and Cell Biology, University of Liverpool, Liverpool L69 3GE, UK
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  • Stanley Salmons MSc, PhD

    1. British Heart Foundation Skeletal Muscle Assist Research Group, Department of Human Anatomy and Cell Biology, University of Liverpool, Liverpool L69 3GE, UK
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Abstract

Rabbit tibialis anterior muscles were stimulated continuously at 2.5 Hz, 5 Hz, or 10 Hz for 10 months. The resulting adaptive transformation was dose-related for contractile speed, myosin isoform composition, and enzyme activities. The “fast-oxidative” state produced by stimulation at 2.5 Hz was stable: even after 10 months, 84% of the fibers were of type 2A. Absence of a secondary decline in oxidative activity in these muscles provided strong evidence of a causal link between myosin transitions and metabolic adaptation. Significant fiber loss occurred only after prolonged stimulation at 10 Hz. The myosin isoform composition of individual muscles stimulated at 5 Hz resembled that of muscles stimulated at either the lower or the higher frequency, behavior consistent with a threshold for fiber type change. In clinical applications such as cardiomyoplasty, muscles could be used more effectively by engineering their properties to combine speed and power of contraction with the necessary resistance to fatigue. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21: 1632–1646, 1998

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