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High superoxide production rates by skeletal muscle mitochondria oxidizing electron shuttle substrates
Author(s) -
Glancy Brian,
Kosak Aida,
Baba Lisa,
Willis Wayne
Publication year - 2007
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.21.6.lb119-c
Subject(s) - skeletal muscle , oligomycin , superoxide , biochemistry , mitochondrion , chemistry , nad+ kinase , biology , atpase , anatomy , enzyme
Glycolysis generates cytosolic reducing equivalents, which enter mitochondria (MITO) via the cytosolic‐mitochondrial electron shuttles; the NAD‐linked malate aspartate (MA) shuttle predominates in type I muscle cells, while the FAD‐linked glycerol‐3‐phosphate (G3P) shuttle is highly active in type II. The purpose of this study was to evaluate superoxide (O 2 .) production in MITO from different fiber types respiring in the presence of various saturating fuels. G3P and glutamate + malate + arsenite (G+M+A) were used to partially reconstruct the G3P and MA electron shuttles, respectively. MITO isolated from rat white and red skeletal muscle were respired in the presence of oligomycin while O 2 . production was followed 30 min. With G+M+A, O 2 . production in both red and white MITO was many fold greater than with pyruvate + malate (P+M). White MITO also produced much greater O 2 . with G3P than with P+M. Further, in both red and white MITO, O 2 . production with G3P and G+M+A was additive. When MITO were respired with glutamate and malate without arsenite, O 2 . production dropped dramatically in red MITO, while only a small decrease was observed in white MITO. These findings may have important implications regarding the interrelationships among reactive oxygen species, excessive carbohydrate availability, skeletal muscle fiber composition, and the development of insulin resistance. Supported by NSF IBN‐0116997