Free radical activity, antioxidant enzyme, and glutathione changes with muscle stretch injury in rabbits

Departments of 1 Family Medicine, 2 Orthopedic Surgery, 3 Kinesiology, 4 Biomedical Engineering, and 5 Mechanical Engineering, University of Wisconsin, Madison, Wisconsin 53711 The present study investigated changes in rate of free radical production, antioxidant enzyme activity, and glutathione status immediately after and 24 h after acute muscle stretch injury in 18 male New Zealand White rabbits. There was no change in free radical production in injured muscles, compared with noninjured controls, immediately after injury ( time 0 ; P = 0.782). However, at 24 h postinjury, there was a 25% increase in free radical production in the injured muscles. Overall, there was an interaction (time and treatment) effect ( P = 0.005) for free radical production. Antioxidant enzyme activity demonstrated a treatment (injured vs. control) and interaction effect for both glutathione peroxidase ( P = 0.015) and glutathione reductase ( P = 0.041). There was no evidence of lipid peroxidation damage, as measured by muscle malondialdehyde content. An interaction effect occurred for both reduced glutathione ( P = 0.008) and total glutathione ( P = 0.015). Morphological analysis (hematoxylin and eosin staining) showed significant polymorphonuclear cell infiltration of the damaged region at 24 h postinjury. We conclude that acute mechanical muscle stretch injury results in increased free radical production within 24 h after injury. Antioxidant enzyme and glutathione systems also appear to be affected during this early postinjury period. free radicals; muscle stretch injury