Protective effects of tea polyphenols on myocardial free radical metabolic disorder in mice induced by inhalation of pure oxygen under 5500 m hypobaric condition.

OBJECTIVE: To observe the protective effects of natural antioxidant tea polyphenols(TP) on myocardial free radical metabolic disorder in mice induced by inhalation of hypobaric pure oxygen under 5500 m hypobaric condition. METHOD: Forty-two male Kunming mice were randomly divided into three groups (n = 14 each): group A, normal control; group B, inhalation of pure oxygen (> 96 %) at simulated altitude of 5500 m in an animal altitude chamber; group C (TP protection group), same as group B but 100 mg/kg of TP was given orally before the exposure. The exposure time was 2 h/d, 3 d/wk for a total of 8 wk, and distilled water was given to groups A and B before exposure. After experiment, the mice were decapitated on the next day and the heart was quickly removed. Malondialdehyde (MDA) concentration, superoxide dismutase (SOD) activity and nitric oxide (NO) content were measured. In addition, Cu, Zn-SOD and inducible NO synthase (iNOS) enzymatic contents in myocardial tissue were qualitatively examined by immunohistochemical assaying. RESULT: Compared with the control, MDA concentration, SOD activity and Cu, Zn-SOD enzymatic content in group B were significantly increased (P < 0. 05). But in TP protection group, myocardial MDA formation was significantly decreased (P < 0. 01) and SOD activity and Cu, Zn-SOD expression restored to normal. On the contrary, myocardial NO generation and iNOS expression were significantly reduced after repeated inhalation of hypobaric oxygen at 5500 m. NO metabolism regained to normal after repeated administration of TP. CONCLUSION: Natural antioxidant TP had protective effects on myocardial free radical metabolic disorder induced by inhalation of hypobaric pure oxygen under 5500 m hypobaric condition.

[Effects of simulated flight hypobaric hypoxia and oxygen inhalation on free radical metabolism in various organs of mice].

Objective. To investigate the effects of two types of simulated flight conditions (hypobaric hypoxia and hypobaric oxygen inhalation) on free radical metabolism in various organs of mice. Method. Sixty male Kunming mice were randomly divided into six groups (n=10 each). The experiment comprises two parts. The first part included three groups: normal controls (A1), 1500 m hypobaric hypoxia for 4 wk (B1) and 8 wk (C1). The second part included another three groups: normal control (A2), 5500 m hypobaric oxygen inhalation for 4 wk (B2) and 8 wk (C2). The exposure time in hypobaric chamber was 2 h/d, 3 d/wk. After experiment, caudal blood was taken for routine examination. The mice were decapitated on the next day and brain, heart, lung, liver and kidney homogenates were prepared for measuring malondialdehyde (MDA) content and superoxide dismutase (SOD) activity. Result. Lipid peroxides in lung was significantly increased in C1 group, and the content of myocardial MDA and myocardial SOD activities in C2 group were markedly higher than those in A2 group. There were no significant differences among body weights, mean corpuscular indices and hemoglobin content in the normal control, hypobaric hypoxia and hypobaric oxygen inhalation groups. It demonstrates that repeated mild hypobaric hypoxia for 8 wk causes free radical damage of lung and repeated exposure to 5500 m hypobaric oxygen inhalation for 8 wk may lead to myocardial peroxidative injury in mice. Conclusion. Simulated flight hypobaric hypoxia and oxygen inhalation may lead to free radicals damage of lung and myocardial peroxidative injury in mice.