Enhanced lipid peroxidation in tourniquet-release mice

BackgroundThe pathogenesis of ischemia–reperfusion involves generation of reactive oxygen and resulting lipid peroxidation. However, investigation that ischemia–reperfusion following tourniquet release enhances lipid peroxidation is insufficient.MethodsTourniquet was applied to a unilateral hind limb of mice for 3 h followed by 5-, 15-, 30- and 60-min release. To examine superoxide production immunohistochemically in ischemia–reperfusion muscles, a primary antibody directed to 4-hydroxy-nonenal (HNE) was used. Furthermore, we analyzed 7α- and 7β-hydroperoxycholest-5-en-3β-ol, 7α- and 7β-hydroxycholesterol, and 7-ketocholesterol by HPLC in the gastrocnemius muscles, kidneys, liver, heart and lungs of mice after 1-h reperfusion.ResultsIncreased HNE immunoreactivitiy was observed in the tourniquet-applied side of gastrocnemius muscles of hind limb particularly after 5-min reperfusion. All the oxysterols were significantly higher in the gastrocnemius muscles of the tourniquet-applied side than of the contralateral muscles. Oxysterols were elevated in the kidneys and the liver. Together with the presence of high blood urea nitrogen, these data indicate that the kidney is vulnerable to ischemia–reperfusion.ConclusionsThe enhanced oxidative stress due to ischemia–reperfusion appears to increase HNE in muscle and oxysterols by peroxidation not only in the gastrocnemius muscles but also in the kidneys and liver.