In vivo EPR measurement of radical reaction in whole mice--influence of inspired oxygen and ischemia-reperfusion injury on nitroxide reduction.

In vivo EPR measurements were carried out with whole mice to evaluate the influence of inspired oxygen and ischemia-reperfusion injury on spin-clearance of the nitroxide radicals which were administered intravenously or intramuscularly. Nitroxide radicals in head, abdomen, or muscle domains were composed of sharp triplet lines. The peak heights decreased gradually with time. The reduction of nitroxide radicals depended both on the inspired oxygen concentration and on the domains. Femoral ischemia-reperfusion injury also affected spin-clearance of the nitroxide radical in the thigh. The results were discussed with regard to the generation of active oxygen species.