ABSTRACT
Nitrogen dioxide (NO2.) is often present in inhaled air and may be generated in vivo from nitric oxide. Exposure of human blood plasma to NO2. caused rapid losses of ascorbic acid, uric acid and protein thiol groups, as well as lipid peroxidation and depletions of alpha-tocopherol, bilirubin and ubiquinol-10. No increase in protein carbonyls was detected. Supplementation of plasma with ascorbate decreased the rates of lipid peroxidation, alpha-tocopherol depletion and loss of uric acid. Uric acid supplementation decreased rates of lipid peroxidation but not the loss of alpha-tocopherol. We conclude that ascorbic acid, protein -SH groups, uric acid and alpha-tocopherol may be important agents protecting against NO2. in vivo. If these antioxidants are depleted, peroxidation of lipids occurs and might contribute to the toxicity of NO2..
Subject(s)
Antioxidants/metabolism , Nitrogen Dioxide/blood , Adult , Blood Proteins/metabolism , Chromatography, High Pressure Liquid , Free Radicals , Humans , In Vitro Techniques , Lipid Peroxidation , Luminescent Measurements , Male , Sulfhydryl Compounds/metabolismABSTRACT
A method has been developed for generation of submicrometer aerosols of sodium sulfite suitable for use in inhalation toxicologic research. Concentrations ranging up to about 30 mg/m3 Na2SO3 were achieved in a 0.44 m3 exposure chamber with an air flow rate of 0.20 m3/min for periods up to 16 days. The coefficient of variation of the sulfite aerosol mass concentration was about 4% during a typical exposure period. The measured mass median aerodynamic diameters (MMADar) of the generated aerosols were 1.2 (+/- 0.2SD) microns with a geometric standard deviation (sigma g) of 1.9 (+/- 0.3SD). The chamber was sampled for gas phase SO2 concentration, and aerosol samples were analyzed for particulate sulfite and sulfate. The fraction of sulfur qas sulfite in the aerosol was usually 95% and was always greater than 90%. Gas phase SO2 amounted to less than 2% of the total S(IV) present in the chamber.
Subject(s)
Aerosols , Sulfites/chemical synthesis , Toxicology/methods , Aerosols/analysis , Particle Size , Sulfites/analysis , Sulfur Dioxide/analysisABSTRACT
Sulfur (IV) aerosols may be generated only as the fully neutralized sulfite by nebulization techniques. Attempts to generate bisulfite and metabisulfite aerosols result in the production of sulfite aerosols and large amounts of SO2. Previous toxicologic studies on metabisulfite and bisulfite aerosols apparently documented the effects of high concentrations of gaseous SO2.
