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Am J Physiol Regul Integr Comp Physiol (April 13, 2006). doi:10.1152/ajpregu.00031.2006
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Submitted on January 12, 2006
Accepted on April 5, 2006

Dynamic responses of the glutathione system to acute oxidative stress in dystrophic mouse (mdx) muscles

Roy W.R. Dudley1, Maya Khairallah2, Shawn Mohammed3, Larry Lands3, Christine Des Rosiers2, and Basil J Petrof1*

1 Respiratory Division, McGill University Health Center, Meakins-Christie Laboratories, McGill University, Montreal, Canada
2 Department of Nutrition and Montreal Heart Institute, University of Montreal, Montreal, Canada
3 McGill University Health Center, Montreal Children's Hospital, Montreal, Canada

* To whom correspondence should be addressed. E-mail: basil.petrof{at}mcgill.ca.

The precise mechanisms underlying skeletal muscle damage in Duchenne muscular dystrophy (DMD) remain ill-defined. Functional ischemia during muscle activation, with subsequent reperfusion during rest, has been documented. Therefore, one possibility is the presence of increased oxidative stress. We applied a model of acute hindlimb ischemia/reperfusion (I/R) in mdx mice (genetic homologue of DMD) to evaluate dynamic in vivo responses of dystrophic muscles to this form of oxidative stress. Prior to the application of I/R, mdx muscles showed: (i) decreased levels of total glutathione with an increased GSSG/GSH ratio; (ii) greater activity of the GSH-metabolizing enzymes, glutathione peroxidase (GPx) and glutathione reductase (GR); and (iii) lower activity levels of NADP-linked isocitrate dehydrogenase (ICDH) and aconitase, two metabolic enzymes which are sensitive to inactivation by oxidative stress and also implicated in GSH regeneration. Interestingly, non-dystrophic muscles subjected to I/R exhibited similar changes in total glutathione, GSSG/GSH, GPx, ICDH, and aconitase. In contrast, all of the above remained stable in mdx muscles subjected to I/R. Taken together, these results suggest that mdx muscles are chronically subjected to increased oxidative stress, leading to adaptive changes that act to protect (although only in part) the dystrophic muscles from acute I/R-induced oxidative stress. In addition, mdx muscles show significant impairment of the redox-sensitive metabolic enzymes ICDH and aconitase, which may further contribute to contractile dysfunction in dystrophic muscles.







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