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Ozone-reactive absorption by pulmonary epithelial lining fluid constituents
S D Langford1, A Bidani, E M Postlethwait
1Department of Internal Medicine, University of Texas Medical Branch, Galveston 77555-0876, USA.
Toxicology and Applied Pharmacology
|May 1, 1995
Summary
Inhaled ozone (O3) is primarily absorbed by the lung's epithelial lining fluid (ELF) through reactive mechanisms, not physical processes. Ascorbate and phospholipids in ELF are key targets for O3 absorption.
Area of Science:
- Environmental Toxicology
- Pulmonary Physiology
- Biochemistry
Background:
- Inhaled ozone (O3) absorption in the lungs is thought to be reaction-dependent.
- The epithelial lining fluid (ELF) is the initial site of O3 interaction with lung tissue.
Purpose of the Study:
- To determine if reactive uptake by ELF constituents explains pulmonary O3 absorption.
- To identify specific ELF constituents that act as O3 absorption targets.
Main Methods:
- Harvested rat ELF via bronchoalveolar lavage, concentrating it by re-instillation.
- Exposed cell-free ELF and model substrates (glutathione) to controlled O3 concentrations.
- Analyzed O3 uptake rates based on temperature, pH, substrate concentration, flow rate, and molecular weight cutoff.
Main Results:
- O3 absorption by ELF and glutathione (GSH) was dependent on substrate concentration and temperature, with calculated activation energies (Ea) and Q10 values.
- Fractional O3 uptake decreased with increasing O3 concentration and flow rate.
- Ascorbate depletion significantly reduced O3 uptake, suggesting it is a primary absorption target.
Conclusions:
- O3 uptake by ELF is reaction-dependent, consistent with observed pH, temperature, and substrate dependencies.
- ELF is the primary site for reactive O3 absorption in the lungs.
- Ascorbate and phospholipids are likely major O3 absorption targets in the ELF.