Kinetics of protein depletion in rat bronchoalveolar lavage fluid following in vitro exposure to nitrogen dioxide

Kinetics of ozone reaction with uric acid, ascorbic acid, and glutathione at physiologically relevant conditions

This study quantified the reaction kinetics of O3 with three low molecular weight antioxidants-uric acid (UA), ascorbic acid (AH2), and glutathione (GSH)-found in respiratory mucous. Using a semi-batch reactor in which a 500 ml/min flow of air containing 1-5 parts per million of O3 contacted 3 ml of well-stirred physiological saline solution containing 100-200 microM antioxidant, we found that: (1) mass transfer resistances in the gas and liquid phases were successfully eliminated by the reactor design; (2) the reaction of O3 with UA, AH2 and GSH had stoichiometries of 1:1, 1:1, and 1:2.5, respectively; (3) the reactivity between O3 and antioxidants was in the order UA approximately AH2>GSH. Simulating the measured amounts of O3 absorbed and antioxidant consumed with a mathematical model, reaction rate constants of O(3) with UA, AH2, and GSH were found to be 5.83 x 10(4) M(-1) s(-1), 5.5 x 10(4) M(-1) s(-1), and 57.5 M(-0.75) s(-1), respectively.

Ozone, but not nitrogen dioxide, exposure decreases glutathione peroxidases in epithelial lining fluid of human lung

Antioxidants, such as glutathione peroxidases (GPxs), in epithelial lining fluid (ELF) protect against health effects of oxidant pollutants, which includes O(3) or NO(2). We hypothesized that GPxs concentration in ELF is responsive to O(3) or NO(2) exposure. Subjects underwent two 4-h exposures to O(3) (0.22 ppm) and one to air. In another experiment, subjects underwent 3-h exposures to air and NO(2) (0.6 and 1.5 ppm). Bronchoalveolar lavage (BAL) was performed immediately or 18 h after O(3) exposure and 3.5 h after each NO(2) exposure. GPx activity and extracellular GPx (eGPx) protein concentrations were determined in ELF, and their relationships to markers of lung function, inflammation, and epithelial permeability were examined. Although the total amounts were not changed, basal (air) GPx activity (223.6 +/- 24.4 mU/ml), basal eGPx protein concentration (2.62 +/- 0.25 microg/ml), and basal ELF dilution factor (152.3 +/- 8.4) decreased 40% immediately after O(3) exposure and remained 30% decreased 18 h after exposure (p = 0.0001). No effect of NO(2) exposure on GPxs concentration was detected. There was an inverse correlation between baseline ELF eGPx protein concentration and the change in PMN 18 h after O(3) exposure (p = 0.04). Thus, O(3), a strong oxidant, decreases both GPx activity and eGPx protein in ELF, whereas NO(2), a weaker oxidant, does not. eGPx in ELF may protect against O(3)-induced airway inflammation.