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Impaired Resting Muscle Energetics Studied by 31 P‐NMR in Diet‐induced Obese Rats
Author(s) -
Chanseaume Emilie,
Bielicki Guy,
Tardy AnneLaure,
Renou JeanPierre,
Freyssenet Damien,
Boirie Yves,
Morio Béatrice
Publication year - 2008
Publication title -
obesity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.438
H-Index - 199
eISSN - 1930-739X
pISSN - 1930-7381
DOI - 10.1038/oby.2007.91
Subject(s) - phosphocreatine , medicine , endocrinology , creatine , adenosine triphosphate , chemistry , skeletal muscle , in vivo , bioenergetics , creatine kinase , sucrose , gastrocnemius muscle , energy metabolism , biology , mitochondrion , biochemistry , microbiology and biotechnology
Objective: Mitochondrial activity is altered in skeletal muscle of obese, insulin‐resistant or type 2 diabetic patients. We hypothesized that this situation was associated with profound adaptations in resting muscle energetics. For that purpose, we used in vivo 31 P‐nuclear magnetic resonance ( 31 P‐NMR) in male sedentary Wistar rats fed with obesogenic diets known to induce alterations in muscle mitochondrial activity. Methods and Procedures: Two experimental diets (high sucrose and high fat) were provided for 6 weeks at two levels of energy (standard, N and high, H) and compared to control diet. The rates of the adenosine triphosphate (ATP) exchange between phosphocreatine (PCr) and γ ‐ATP ( k a ) and β ‐adenosine diphosphate ( β ‐ADP) to β ‐ATP ( k b ) were evaluated using 31 P‐NMR in resting gastrocnemius muscle. Muscle contents in phosphorylated compounds as well as creatine, were assessed using 31 P‐NMR and biochemical assays, respectively. Results: ATP content increased by 6.7–8.5% in standard‐energy high‐sucrose (NSU), high‐energy high‐fat (HF) and high‐energy high‐sucrose (HSU) groups compared to control ( P < 0.05), whereas PCr content decreased by 4.2–6.4% ( P < 0.01). Consequently, PCr to ATP ratio decreased in NSU, HF, and HSU groups, compared to control ( P < 0.01). Furthermore in high‐energy groups (HF and HSU) compared to control, creatine contents were decreased by 14–19% ( P < 0.001), whereas k a and k b fluxes were increased by 89–133% ( P < 0.001) and 243–277% ( P < 0.01), respectively. Discussion: Our in vivo data showed adaptations of resting skeletal muscle energetics in response to high‐energy diets. Increased activity of enzymes catalyzing ATP production may reflect a compensatory mechanism to face impaired mitochondrial ATP synthesis in order to preserve intracellular energy homeostasis.