Enhancement of superoxide dismutase activity in rat lungs after hypoxic preconditioning.

Ischemic preconditioning has been proved to reduce tissue damages and benefit subsequent organ transplantation. Chronic hypoxic preconditioning was found to increase the levels of lung antioxidants. This study was to test the hypothesis that levels of lung antioxidants might increase after hypoxia which may counteract the insults of free radicals. Female Wistar rats were kept in an altitude chamber (380 torr) 15 h a day for 4 weeks (hypoxia-adapted). Controls were kept at room air pressure (sea-level). After hypoxic preconditioning, no significant difference in the levels of the oxidative markers, malondialdehyde, thiobarbituric acid reactive substances and isoprostane was seen in the lungs of the hypoxia-adapted rats compared to the sea-level controls. Both the activity and protein level of manganese superoxide dismutase were higher in hypoxia-adapted lungs. Lung manganese superoxide dismutase mRNA levels, determined by real-time RT-PCR, were not significantly different in the two groups of rats. When isolated saline-perfused lungs were prepared and treated with xanthine (500 microM) and xanthine oxidase (5 mU/ml), and the levels of free radicals in the perfusate determined by chemiluminescence, less chemiluminescence was seen in the hypoxia-adapted lung perfusate. When the vascular response was determined in this same preparation before or 45 min after xanthine/xanthine oxidase treatment, the filtration coefficient was increased in the sea-level lungs but not in the hypoxia-adapted lungs. We conclude that an increase in superoxide dismutase activity and protein levels is one of the benefits of hypoxic preconditioning.

Reduction of hexa(sulfobutyl)fullerence on oxidative injury by xanthine and xanthine oxidase in isolated rat lungs.

UNLABELLED: The present study was undertaken to evaluate whether some fullerenols could effectively reduce direct damages of free radicals produced by xanthine/xanthine oxidase (X/XO) in isolated rat lungs. METHODS: Female Wistar rats (205 +/- 4 g) were used in studies in pulmonary vascular response to the challenge of xanthine/xanthine oxidase by an isolated-perfused lung method. Free radicals were determined by chemiluminescence (CL) to confirm the release of free radicals after X/XO treatment. The CL count in the lung perfusate was 737 +/- 213 (CL/10 sec); 5 min and 45 min after X/XO administration, the CL counts were 3,778 +/- 425 (CL/10 sec) and 1,183 +/- 193 (CL/10 sec), respectively. Challenge with X/XO caused a mild but significant increase in pulmonary arterial pressure (P(pa)) and a marked increase of filtration coefficient (K(fc)). The pretreatment of Hexa (sulfobutyl) fullerence antioxidant, K(fc) became insignificantly increased in pretreated lungs. In conclusion, We found that hexa(sulfobutyl) fullerene, but not Co60(glucosamine)6, nor superoxide dismutase could attenuate the oxidative stress, judged from the attenuated increase in pulmonary filtration coefficient after challenge.