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

The present study investigated changes in rate of free radical production, antioxidant enzyme activity, and glutathione status immediately after and 2 4 h after acute muscle stretch injury in 18 male New Zealand White rabbits. There was no change in free radical production in injured muscles, compare d with noninjured controls, immediately after injury (time 0; P = 0.782). H owever, at 24 h postinjury, there was a 25% increase in free radical produc tion in the injured muscles. Overall, there was an interaction (time and tr eatment) effect (P = 0.005) for free radical production. Antioxidant enzyme activity demonstrated a treatment (injured vs, control) and interaction ef fect for both glutathione peroxidase (P = 0.015) and glutathione reductase (P = 0.041). There was no evidence of lipid peroxidation damage, as measure d by muscle malondialdehyde content. An interaction effect occurred for bot h reduced glutathione (P = 0.008) and total glutathione (P = 0.015). Morpho logical analysis (hematoxylin and eosin staining) showed significant polymo rphonuclear cell infiltration of the damaged region at 24 h postinjury. We conclude that acute mechanical muscle stretch injury results in increased f ree radical production within 24 h after injury. Antioxidant enzyme and glu tathione systems also appear to be affected during this early postinjury pe riod.