Evaluation and comparison of the effect of hypothermia and ozone on ischemia-reperfusion injury of skeletal muscle in rats.

BACKGROUND: Tourniquet-induced ischemia-reperfusion, which affects local and distant organs, is very common in orthopedic surgery. Hypothermia is used in traumatic tissue during ischemic period commonly. Ozone (O3) has been recommended as a novel therapeutic agent in various medical conditions. The objective of the study was to evaluate and compare the effect of hypothermia (H) and O3 on ischemia-reperfusion injury of skeletal muscle in rats by measuring oxidative parameters and inducible nitric oxide synthase (iNOS) levels.

MATERIALS AND METHODS: Eighteen rats (Wistar albino) were separated into five groups randomly (sham, IR, IR + H, IR + O3, IR + H + O3; n = 6). The lower right extremity of all rats was subjected to 2 h of ischemia and 22 h of reperfusion clamping the common iliac artery and using the rubber-band technique at the level of the lesser trochanter under general anesthesia. Two hours of hypothermia were applied during the first 2 h of reperfusion in two groups. O3 was applied in two groups. All rats were sacrificed after the IR period with high dose of anesthesia. The tibialis anterior muscle and blood were saved. Levels of superoxide dismutase, glutathione peroxidase, MDA, NOx, and interleukin-1β were measured in the muscle. Creatinine kinase, lactate dehydrogenase, aspartate aminotransferase, urea, creatinine, and electrolytes were measured in serum. Immunohistochemical iNOS staining was performed on muscle samples.

RESULTS: The levels of MDA, NOx, and interleukin-1β in muscle were raised in the IR group compared with those in the sham group. The same parameters were lower in the groups of IR + H, IR + O3, and IR + H + O3 compared with those in the IR group. Superoxide dismutase and glutathione peroxidase activities in muscle were lower in the IR group compared with those in the sham group; however, same parameters were higher in the groups of IR + H, IR + O3, and IR + H + O3 compared with those in the IR group. Score and intensity of iNOS staining in skeletal muscle in the IR group was increased compared with that in the sham group and decreased in the groups of IR + H, IR + O3, and IR + H + O3 compared with that in the IR group. Levels of creatinine kinase, aspartate aminotransferase, and K in the three treatment groups decreased compared with those in the IR group.

CONCLUSIONS: These findings showed that hypothermia, which has more affect, and O3 decreased the tourniquet-induced IR injury in the rat's muscle-skeletal system by reducing the levels of oxidative and nitrosative stress parameters and enhancing antioxidant enzymes. Hypothermia and O3 had no synergistic effect. Hypothermic reperfusion and O3 preconditioning might be beneficial in skeletal muscle IR injury-associated tourniquet.