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Effects of glucocorticoids on motor units in cat hindlimb muscles
Author(s) -
Robinson Andrew J.,
Clamann H. Peter
Publication year - 1988
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880110706
Subject(s) - glucocorticoid , cats , endocrinology , medicine , weakness , motor unit , hindlimb , muscle atrophy , atrophy , triamcinolone acetonide , soleus muscle , muscle weakness , chemistry , anatomy , biology , skeletal muscle , surgery
The purpose of this study was to examine the effects of glucocorticoid treatment on the contractile, electrical and fatigue properties of isolated motor units of identified type. Although it is known that glucocorticoid administration induces atrophy and weakness most strongly in fast, pale muscles and to a lesser extent in red muscle, the relationship between steroid effects and motor unit type is not known. Properties of medial gastrocnemious (MG) and soleus (SOL) motor units were studied in normal cats and in cats treated with triamcinolone acetonide (3–4 mg/kg body weight for 10–16 days). Glucocorticoid treatment produced weakness preferentially in fast‐twitch motor units. This suggests that catabolic steroids cause a reduction in the amount of contractile protein and hence contractile strength of motor units in inverse proportion to their relative activity or degree of use.