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Studies of mitochondrial and non‐mitochondrial sources implicate NADPH oxidase(s) in the increased skeletal muscle superoxide generation that occurs during contractile activity
Author(s) -
Sakellariou Giorgos K,
Vasilaki Aphrodite,
Palomero Jesus,
Kayani Anna,
Zibrik Lea,
McArdle Anne,
Jackson Malcolm J
Publication year - 2012
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.26.1_supplement.1078.22
Subject(s) - superoxide , nadph oxidase , sarcolemma , cytosol , chemistry , mitochondrion , skeletal muscle , biochemistry , microbiology and biotechnology , myocyte , biology , reactive oxygen species , anatomy , enzyme
Superoxide generated by skeletal muscle acts to modulate force generation and contraction‐induced changes in gene expression. This study identified the sub‐cellular sites of muscle fibre superoxide generation. Single isolated mature fibres from mouse flexor digitorum brevis loaded with superoxide‐sensitive fluorescent probes, specific inhibitors of potential pathways and immunolocalisation techniques were used. Comparison of voltage dependent anion channel or Bax channel inhibitors following contractile activity or treatment with the mitochondrial compex III inhibitor, antimycin A, indicated that superoxide could exit mitochondria via these channels, but they did not contribute to contraction‐induced increases in cytosolic superoxide. NADPH oxidase inhibitors decreased superoxide at rest and following contractions compared with controls. Protein and mRNA expression of NADPH oxidase subunits were demonstrated in fibres. At rest, NOX2, NOX4 and p22 phox subunits localized to the sarcolemma and transverse tubules and the regulatory subunits p40 phox and p67 phox localized to the cytoplasm. Following contractions, p40 phox was observed to translocate from the fibre cytosol to the sarcolemma. NADPH oxidase is a major contributor to cytosolic superoxide in muscle and its activation by contractions involves translocation of p40 phox from the cytosol to the sarcolemma. Funded by NIA (AG‐20591)