In vivo evidence of abnormal mechanical and oxidative functions in the exercised muscle of dystrophic hamsters by 31P-NMR.
Mechanical properties and metabolic adaptation to exercise in skeletal muscle of dystrophic hamsters were studied with an in vivo 31P-NMR multistep fatigue test. Three successive 20-min steps with increasing rhythms of tetanic stimulation were followed by a 20-min recovery period. Fatigue in dystrophic hamsters (DH) developed more rapidly and was greater than in normal hamsters (NH); total mechanical performance per min increased step by step in NH while it decreased in DH, showing a progressive mechanical impairment of the dystrophic muscles. ADP and PCr recovery rates were significantly reduced in DH muscles. Acidosis appeared in both DH and NH and persisted in DH throughout the test, suggesting reduced mitochondrial oxidative capacity of the dystrophic muscle. The pH recovery rate was reduced in DH muscles suggesting a reduction in export protons capacity. These results provide evidence of impaired mitochondrial function and intracellular ionic regulation in the dystrophic muscle, associated with the lack of dystrophin and dystrophin-associated glycoproteins in the DH.
Le Rumeur
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E
Laboratoire de RMN en Biologie et Médecine, LRMBM, Rennes, France.
Le Tallec
N
N
Lewa
C J
CJ
Ravalec
X
X
de Certaines
J D
JD
D000704:Analysis of Variance; D000818:Animals; D001696:Biomechanical Phenomena; D006224:Cricetinae; D004734:Energy Metabolism / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000503:physiopathology*; D009137:Muscular Dystrophy, Animal / Q000378:metabolism / Q000503:physiopathology*; D010084:Oxidation-Reduction; D010725:Phosphocreatine / Q000378:metabolism; D010758:Phosphorus; D010805:Physical Conditioning, Animal / Q000502:physiology*
D010725:Phosphocreatine; D010758:Phosphorus