Premium
Post‐ or Pre‐Injury Concentric Contractions Do Not Reduce Eccentric‐Contraction‐Induced Myofiber Damage in a Murine Model of Dysferlin‐linked Muscular Dystrophy
Author(s) -
Begam Morium,
Collier Alyssa F,
Basel Chantel A,
Blackmer Jacob M,
Hass Joshua J,
Konja Jasmine T,
Samojedny Amber L,
Roche Joseph A
Publication year - 2017
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.31.1_supplement.1022.18
Subject(s) - eccentric , dysferlin , contraction (grammar) , myocyte , concentric , medicine , muscle contraction , sarcolemma , anatomy , skeletal muscle , endocrinology , mathematics , quantum mechanics , physics , geometry
Background Concentric contractions have been shown to reduce delayed onset muscle soreness following eccentric contractions in healthy human subjects. Dysferlin‐deficient muscle undergoes severe delayed onset myofiber damage over several days after eccentric contractions. The goal of our study was to test the hypothesis that concentric contractions reduce eccentric‐contraction‐induced myofiber damage in dysferlin‐deficient muscle. Methods We studied the tibialis anterior (TA) muscle in 3–4 month old, male, dysferlin‐null BLAJ mice. We elicited TA muscle contractions by depolarizing the fibular nerve with an electrical stimulator; and used a custom‐built dynamometer to measure contractile torque and expose the TA muscle to eccentric contractions (one bout; 40 repetitions; 90–160 □ plantarflexion superimposed on maximal tetany of ankle dorsiflexors). We exposed one group of mice to a single bout of 20, maximal, unloaded concentric contractions soon after eccentric contractions (ConEx after EccEx; N = 4 mice); exposed a second group to 6 sessions of maximal, unloaded concentric contractions (40 repetitions/session) over 2 weeks (ConEx before EccEx; N = 4); and designated a third group as controls (Untreated; N =4). We studied contractile torque before, immediately after, and 3 days after eccentric contractions. We collected TA muscles 3 days after eccentric contractions to histologically assess myofiber damage through hematoxylin and eosin staining, and through immunoglobulin‐G (IgG) and desmin immunofluorescent labeling. Results Summarized in Table 1. Conclusion Neither post‐ nor pre‐injury concentric contractions reduce eccentric‐contraction‐induced myofiber damage in dysferlin‐deficient skeletal muscle. Support or Funding Information Funded by a Faculty Startup Package to JAR. Dysferlin‐null BLAJ mice were a kind gift from the Jain Foundation Inc. 1 Physiological and Histological DataOutcome Measure Untreated (Mean ± S.E.M.) ConEx after EccEx (Mean ± S.E.M.) ConEx before EccEx (Mean ± S.E.M.) Statistically Significant DifferenceTorque ‐ Immediately After Eccentric Contractions (% Pre) 52 ± 8 46 ± 1 49 ± 2 No Torque ‐ 3 Days After Eccentric Contractions (% Pre) 37 ± 9 34 ± 1 38 ± 2 No % Damaged Fibers ‐ 3 Days After Eccentric Contractions (H&E Staining) 42 ± 3 44 ± 2 41 ± 2 No % IgG+ and Desmin‐Fibers ‐ 3 Days After Eccentric Contractions 40 ± 3 43 ± 3 38 ± 3 No