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Relation between in vivo and in vitro measurements of skeletal muscle oxidative metabolism
Author(s) -
LarsonMeyer D. Enette,
Newcomer Bradley R.,
Hunter Gary R.,
Joanisse Denis R.,
Weinsier Roland L.,
Bamman Marcas M.
Publication year - 2001
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.1202
Subject(s) - phosphocreatine , oxidative phosphorylation , in vivo , isometric exercise , adenosine triphosphate , skeletal muscle , citrate synthase , cytochrome c oxidase , medicine , endocrinology , chemistry , mitochondrion , adenosine diphosphate , biochemistry , biology , enzyme , energy metabolism , microbiology and biotechnology , platelet , platelet aggregation
The relationships between in vivo 31 P magnetic resonance spectroscopy (MRS) and in vitro markers of oxidative capacity (mitochondrial function) were determined in 27 women with varying levels of physical fitness. Following 90‐s isometric plantar flexion exercises, calf muscle mitochondrial function was determined from the phosphocreatine (PCr) recovery time constant, the adenosine diphosphate (ADP) recovery time constant, the rate of change of PCr during the initial 14 s of recovery, and the apparent maximum rate of oxidative adenosine triphosphate (ATP) synthesis (Q max ). Muscle fiber type distribution (I, IIa, IIx), citrate synthase (CS) activity, and cytochrome c oxidase (COX) activity were determined from a biopsy sample of lateral gastrocnemius. MRS markers of mitochondrial function correlated moderately ( P < 0.05) with the percentage of type IIa oxidative fibers ( r = 0.41 to 0.66) and CS activity ( r = 0.48 to 0.64), but only weakly with COX activity ( r = 0.03 to 0.26, P > 0.05). These results support the use of MRS to determine mitochondrial function in vivo. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 1665–1676, 2001