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Dystrophin is not required for skeletal muscle to adapt to repeated bouts of lengthening contractions
Author(s) -
Call Jarrod A,
Eckhoff Michael D,
Baltgalvis Kristen A,
Warren Gordon L,
Lowe Dawn A
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1105.13
Subject(s) - isometric exercise , contractility , skeletal muscle , anatomy , dystrophin , in vivo , medicine , extensor digitorum longus muscle , chemistry , endocrinology , biology , microbiology and biotechnology
Functional adaptations of the anterior crural muscles [tibialis anterior (TA), extensor digitorum longus (EDL)] of mdx mice to five repeated bouts of 100 injurious lengthening contractions were investigated. Each bout was separated by 10 days and in vivo maximal isometric torque of the anterior crural muscles was also assessed before and after each bout. EDL muscle contractility was tested ex vivo following the final bout, and biochemical and histological analyses followed. There was no attenuation in the loss of strength from repeated bouts of lengthening contractions (P=0.68); however, there were 3–11% increases in maximal isometric torque following recovery from each bout (P<0.001). EDL muscles that were conditioned from previous bouts of lengthening contractions had improved rates of recovery 3 days following the final bout compared to unconditioned EDL muscles (84% vs 74% recovered, P=0.048). Conditioned EDL muscles also had greater specific force (12.2 vs 10.4 N/cm 2 , P=0.005). Skeletal muscle adaptations that may contribute to the functional outcomes include: smaller and fewer centrally nucleated fibers, increased dry:wet mass ratio, and enhanced contractile protein and parvalbumin expression. Dystrophic skeletal muscle does adapt to repeated bouts of lengthening contractions by improving recovery of strength. Supported by: NIH T32‐AR07612