Antioxidants in Bronchoalveolar Lavage Fluid Cells Isolated from Ozone—Exposed Normal and Ascorbate-Deficient Guinea Pigs

Abstract

Previous studies have indicated that systemic deficiency in one of the critical antioxidants, ascorbate, does not significantly exacerbate ozone-induced lung injury and changes in lung antioxidants following longer-term exposure. Because alveolar cells encounter the highest ozone dose upon exposure and lack direct blood supply, systemic ascorbate deficiency may exacerbate ozone response on antioxidants within these cells. Female Hartley guinea pigs (30 days old) were fed either a regular guinea pig chow or chow that lacked ascorbate. The dietary regimen was started I week prior to exposure, continued through ozone exposure (0, 0.2, 0.4, or 0.8 ppm, 23 h/day, 1 week), and during 1 week recovery in clean air following exposure. Immediately after 1 week of exposure or recovery, lungs were lavaged and cells were counted in bronchoal-veolar lavage fluid (BALF). Protein, ascorbate, uric acid, total glutathione (GSH), and α-tocopherol were analyzed in these cells. Ozone caused an increase in total BALF cells and total cellular protein after 0.4 and 0.8 ppm ozone. The increase was more pronounced in ascorbate-deficient guinea pigs. Protein per million cells, however, was not changed by ozone or diet. In ascorbate-sufficient guinea pigs, ascorbate levels were increased only after 0.2 ppm ozone. However, uric acid (at 0.4 and 0.8 ppm ozone) and GSH (at all concentrations of ozone) levels were increased in both dietary groups. Ascorbate deficiency did not affect basal uric acid or GSH levels in BALF cells. There was a small diet-related depletion in cellular α-tocopherol. Ozone exposure also decreased a-tocopherol regardless of diet. The above changes except for α-tocopherol appeared to be reversed after 1 week of recovery in both dietary groups. In summary, ozone is capable of inducing a mechanism that increases antioxidants such as ascorbate, GSH, and uric acid. GSH and uric acid are not affected by ascorbate deficiency, but α-tocopherol is depleted. GSH and uric acid may be critical in ozone-induced adaptation during ascorbate deficiency.

Key Words:

• alveolar cells
• antioxidants
• ascorbate deficiency
• guinea pigs
• ozone