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Reactive oxygen species and fatigue-induced prolonged low-frequency force depression in skeletal muscle fibres of rats, mice and SOD2 overexpressing mice

Bruton, Joseph D.
Yamada, Takashi
Silva, Jose P.
Andrade, Francisco H.
Dahlstedt, Anders J.
Zhang, Shi-Jin
Katz, Abram
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Published in Journal of physiology. 2008, vol. 586, no. 1, p. 175-184
Abstract Skeletal muscle often shows a delayed force recovery after fatiguing stimulation, especially at low stimulation frequencies. In this study we focus on the role of reactive oxygen species (ROS) in this fatigue-induced prolonged low-frequency force depression. Intact, single muscle fibres were dissected from flexor digitorum brevis (FDB) muscles of rats and wild-type and superoxide dismutase 2 (SOD2) overexpressing mice. Force and myoplasmic free [Ca(2+)] ([Ca(2+)](i)) were measured. Fibres were stimulated at different frequencies before and 30 min after fatigue induced by repeated tetani. The results show a marked force decrease at low stimulation frequencies 30 min after fatiguing stimulation in all fibres. This decrease was associated with reduced tetanic [Ca(2+)](i) in wild-type mouse fibres, whereas rat fibres and mouse SOD2 overexpressing fibres instead displayed a decreased myofibrillar Ca(2+) sensitivity. The SOD activity was approximately 50% lower in wild-type mouse than in rat FDB muscles. Myoplasmic ROS increased during repeated tetanic stimulation in rat fibres but not in wild-type mouse fibres. The decreased Ca(2+) sensitivity in rat fibres could be partially reversed by application of the reducing agent dithiothreitol, whereas the decrease in tetanic [Ca(2+)](i) in wild-type mouse fibres was not affected by dithiothreitol or the antioxidant N-acetylcysteine. In conclusion, we describe two different causes of fatigue-induced prolonged low-frequency force depression, which correlate to differences in SOD activity and ROS metabolism. These findings may have clinical implications since ROS-mediated impairments in myofibrillar function can be counteracted by reductants and antioxidants, whereas changes in SR Ca(2+) handling appear more resistant to interventions.
Keywords Acetylcysteine/pharmacologyAnimalsAntioxidants/pharmacologyCalcium/metabolismDithiothreitol/pharmacologyGene Expression Regulation, EnzymologicMaleMiceMice, Inbred StrainsMuscle Contraction/drug effects/*physiologyMuscle Fatigue/*physiologyMuscle, Skeletal/*metabolismRatsReactive Oxygen Species/*metabolismSarcoplasmic Reticulum/metabolismSuperoxide Dismutase/genetics/*metabolism
PMID: 18006575
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Other version: http://jp.physoc.org/content/586/1/175.full.pdf
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BRUTON, Joseph D. et al. Reactive oxygen species and fatigue-induced prolonged low-frequency force depression in skeletal muscle fibres of rats, mice and SOD2 overexpressing mice. In: Journal of physiology, 2008, vol. 586, n° 1, p. 175-184. doi: 10.1113/jphysiol.2007.147470 https://archive-ouverte.unige.ch/unige:19155

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Deposited on : 2012-03-27

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