Background. Oxygen is routinely administered to patients to improve clinical outcome. Since studies have shown that administering 100% oxygen can cause unwanted side effects, intermediate concentrations of 40% oxygen are used in clinical practice. In this study, we examined whether the breathing of 40% oxygen causes beneficial effects upon tissue levels of antioxidants such as vitamin E, vitamin C, and glutathione. Methods. Four-month-old mice were separated into two groups: control (n = 11) and experimental (n = 11). The treatment group was administered 40% oxygen for 10 days. Brain, heart, lung, liver, testes, and skeletal muscle were harvested and tissue antioxidant levels were determined by HPLC. Results. Vitamin E concentrations were higher in brain, heart, lung, liver, and testes of the treatment group (P < 0.05). Glutathione concentrations were higher in the lung tissue only (P < 0.05). No differences were found in vitamin C levels. Conclusions. The data suggest that mice respond to oxidative stress by increasing tissue vitamin E incorporation and cellular synthesis of glutathione in the lung when exposed to moderate levels (40%) of hyperoxia.
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Oxygen is essential for maintaining life of all aerobic organisms. The improvement of tissue oxygenation has been a major goal in clinical practice with several excellent clinical studies showing that improved tissue oxygenation can improve outcome [1, 2] . In clinical practice, supplemental oxygen concentrations of 40% in inspired air is routinely used to improve organ viability. A National Institutes of Health (NIH) consensus conference on oxygen therapy recommended the use of supplemental oxygen (40% inspired) in uncomplicated myocardial infarction, and the judicious use of oxygen in other situations such as postoperative states, chronic hypoxemic pulmonary diseases, and angina pectoris  . The American College of Surgeons' Committee on Trauma recommends that supplemental oxygen be administered to all trauma patients to improve outcome  . This is supported by limited experimental data. For example, a randomized prospective study of 107 high-risk surgical patients showed that patients with higher tissue oxygen levels had a 75% decrease in mortality when compared to controls  . The number of complications such as respiratory failure, acute renal failure, sepsis, pulmonary edema, and other such morbidities were also decreased by 50% in the treatment group. Oxygen is intimately involved in the killing of bacteria by neutrophils that use superoxide radicals, a product of oxygen  . This salutary effect of oxygen is confirmed in a clinical study where the postoperative wound infection rate fell to 5.2% from 11.2% for controls when 80% supplemental oxygen was administered to 500 postsurgical patients for 2 h postoperatively  .
- Oxidative stress
- Vitamin E