Pressure-related effects of hyperbaric oxygen exposure on oxidation products and antioxidant enzymes in the rat lung.

Objective: The aim of this study is to provide comprehensive information on the relationship between clinically used hyperbaric oxygen (HBO) protocols and its oxidative effects. In order to enlighten this issue, we investigated the effects of various HBO pressure modalities on oxidant and antioxidant parameters in the rat lung. Methods: Sixty male Sprague-Dawley rats were divided into 6 groups. Group 1 was used as control. Groups 2 to 6 were subjected to 100% oxygen at a pressure of 1, 1.5, 2, 2.5, and 3 ATA (atmosphere absolute) respectively for 2 hours. The lungs were taken immediately after exposure. Oxidation products of lipids (thiobarbituric acid reactive substances, TBARS) and proteins (carbonyl formation, PCO), and antioxidant enzyme levels (superoxide dismutase, SOD; catalase, CAT, glutathione peroxidase, GSH-Px) were determined. Results: TBARS, PCO, SOD and CAT levels increased concordantly with pressure. Significant change of TBARS levels started from 100% oxygen exposure at 1 ATA (normobaric), but PCO and CAT levels were affected first after 1.5, and SOD activity after 2 ATA. A significant correlation exists between exposure pressure and oxidative parameters. GSH-Px activity was not affected significantly. Conclusion: The oxidative effect of HBO in rat lung presents a positive correlation with increasing exposure pressure. [ABSTRACT FROM AUTHOR]