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Recovery from 6 weeks of repeated strain injury to rat soleus muscles
Author(s) -
Stauber W.T.,
Smith C.A.,
Miller G.R.,
Stauber F.D.
Publication year - 2000
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 - 10.1002/1097-4598(200012)23:12<1819::aid-mus4>3.0.co;2-2
Subject(s) - soleus muscle , strain (injury) , medicine , pyridinoline , fibrosis , myocyte , endocrinology , muscle tissue , skeletal muscle , anatomy , chemistry , biochemistry , alkaline phosphatase , osteocalcin , enzyme
Recovery from chronic strain injury (50 strains daily, five times weekly for 6 weeks to hyperactive soleus muscles) was followed for 3 months in female rats after cessation of chronic hyperactivity induced by pretreatment of the plantar flexor muscles with tetanus toxin. After 6 weeks of repeated strains, muscle mass decreased by 62%, myofiber areas were reduced by 87%, and noncontractile tissue expanded dramatically by 222%. Collagen content increased by almost ninefold (control 40 ± 3 μg/mg, chronic injury 392 ± 53 μg/mg), whereas the molar ratio of collagen (pyridinoline) crosslinks to collagen remained the same (control 0.20 ± 0.01, chronic injury 0.16 ± 0.01). After 3 months of ambulation, muscle mass returned to normal but myofiber areas remained smaller by 21%, noncontractile tissue was still markedly elevated by 18% with increased collagen content (107 ± 15 μg/mg), and the molar ratio of crosslinks to collagen increased by 75% during recovery. Thus, rat soleus muscles recovered very slowly and incompletely from chronic strain injuries that produced muscle fibrosis, highlighting the necessity of devising preventative strategies for repeated strain injuries. © 2000 John Wiley & Sons, Inc. Muscle Nerve 23: 1819–1825, 2000