title: Energy-rich phosphates in slow and fast human skeletal muscle.
abstract: We investigated the relationship between energy-rich phosphate content and muscle fiber-type composition in human skeletal muscle using a combination of 31P-nuclear magnetic resonance spectroscopy (NMR), histochemical, and biochemical analyses of muscle biopsies. Localized 31P spectra were collected simultaneously from the predominantly slow-twitch soleus muscle and the mixed (fast-twitch and slow-twitch) medial and lateral gastrocnemius muscles, using B1-insensitive Hadamard Spectroscopic Imaging. Biopsy samples were taken from the soleus and lateral gastrocnemius muscles before NMR investigation and analyzed for fiber type composition and succinic dehydrogenase (SDH) activity. Fiber-type composition was determined based both on myofibrillar actomyosin ATPase activity combined with cross-sectional area and on myosin heavy-chain composition. Localized spectroscopy demonstrated a significantly (P < 0.001) higher P(i)/phosphocreatine ratio in the soleus muscle (0.15 +/- 0.01) compared with the medial (0.12 +/- 0.01) and lateral (0.10 +/- 0.0) gastrocnemius. However, in vitro analysis of muscle biopsies showed only a moderate relationship between the basal phosphate content and myofibrillar actomyosin ATPase-based fiber-type composition and SDH activity, respectively.
authors.affiliation: Department of Rehabilitation Medicine, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: K
authors.initials: K
authors.lastname: Vandenborne
authors.forename: G
authors.initials: G
authors.lastname: Walter
authors.forename: L
authors.initials: L
authors.lastname: Ploutz-Snyder
authors.forename: R
authors.initials: R
authors.lastname: Staron
authors.forename: A
authors.initials: A
authors.lastname: Fry
authors.forename: K
authors.initials: K
authors.lastname: De Meirleir
authors.forename: G A
authors.initials: GA
authors.lastname: Dudley
authors.forename: J S
authors.initials: JS
authors.lastname: Leigh
mesh_terms: D000293:Adolescent; D000328:Adult; D004734:Energy Metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism*; D018657:Muscle Fibers, Slow-Twitch / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*; D010758:Phosphorus; D010806:Physical Education and Training; D015203:Reproducibility of Results; D013177:Sports; D013385:Succinate Dehydrogenase / Q000378:metabolism
chemical_list: D010710:Phosphates; D010758:Phosphorus; D013385:Succinate Dehydrogenase