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Adaptive conditioning of skeletal muscle in a large animal model ( Sus domesticus )
Author(s) -
Sutherland Hazel,
Salmons Stanley,
Ramnarine Ian R.,
Capoccia Massimo,
Walsh Adrian A.,
Jarvis Jonathan C.
Publication year - 2006
Publication title -
journal of anatomy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.932
H-Index - 118
eISSN - 1469-7580
pISSN - 0021-8782
DOI - 10.1111/j.1469-7580.2006.00598.x
Subject(s) - stimulation , myosin , conditioning , skeletal muscle , immunohistochemistry , population , fibre type , biology , anatomy , biomedical engineering , neuroscience , microbiology and biotechnology , medicine , immunology , mathematics , statistics , environmental health
Recognition of the adaptive capacity of mammalian skeletal muscle has opened the way to a number of clinical applications. For most of these, the fast, fatigue‐susceptible fibres need to be transformed stably to fast, fatigue‐resistant fibres that express the 2A myosin heavy chain isoform. The thresholds for activity‐induced change are size‐dependent, so although the requisite patterns of electrical stimulation are known for the rabbit, in humans these same patterns would produce type 1 fibre characteristics, with an undesirable loss of contractile speed and power. We have used histochemistry, immunohistochemistry and electrophoretic separations to evaluate a possible conditioning regime in a large animal model. Stimulation of the porcine latissimus dorsi muscle with a phasic 30‐Hz pattern for up to 41 days converted all type 2X and 2A/2X fibres to 2A with only a small increase in the type 1 population, from 17% to 22%. Stimulation for longer periods increased the proportion of type 1 fibres to 52%. Based on this model, stimulation regimes designed to achieve a stable 2A phenotype in humans should deliver fewer stimulating impulses, possibly by a factor of 2, than the pattern assessed here. Any such pattern needs to be tested for at least 8 weeks.