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Increased Myosin Light Chain 3f Content Restores Age‐Induced Slowing of Single Skeletal Muscle Fiber Contraction
Author(s) -
Kim JongHee,
Torgerud Windy S.,
Mosser Kelsey H. H.,
Watanabe Shuichi,
Asakura Atsushi,
Thompson LaDora V.
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.1049.1
Subject(s) - myosin , contraction (grammar) , skeletal muscle , chemistry , medicine , muscle contraction , endocrinology , myosin light chain kinase , biophysics , biology , biochemistry
Aging is characterized by a progressive loss of muscle mass and impaired contractile functions (e.g. decline in force, velocity and power). Although these phenomena in aging muscle are well described, the underlying molecular mechanisms responsible for a decrease in contraction speed are not defined. Evidence suggests that the slowing of muscle contraction, as demonstrated by slower unloaded shortening velocity (Vo), is correlated with a decrease in relative myosin light chain 3f (MLC 3f ) content. In the current study, we first established recombinant adenovirus (rAd) gene transfer technology to increase MLC 3f content in semimembranosus muscles of aged rats. We hypothesized that 1) age‐induced decline in Vo would be associated with a decrease in relative MLC 3f content and 2) increasing MLC 3f content via rAd would restore Vo in myosin heavy chain (MHC) type II fibers. Vo (3.2±0.2 vs. 2.2±0.2 FL/s), %MLC 3f (13.6±1.0 vs. 3.7±0.3%) and MLC 3f /MLC 2f ratio (0.28±0.04 vs. 0.10±0.01) decreased with age in type II single fibers. Increasing %MLC 3f to 8.0% and MLC 3f /MLC 2f ratio to 0.20 via rAd provided significant protection against age‐induced reduction in Vo without causing muscle damage or influencing single fiber diameter, force and MHC composition. To the best of our knowledge, these are the first data to demonstrate affirmative effects of MLC 3f against slowing of contraction in aged skeletal muscle. RO1AG017768