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Reactive absorption of nitrogen dioxide by pulmonary epithelial lining fluid
E M Postlethwait1, S D Langford, A Bidani
1Department of Internal Medicine, University of Texas Medical Branch, Galveston 77550.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|August 1, 1990
Summary
The study found that nitrogen dioxide (NO2) absorption in rat lungs is limited by chemical reactions within the epithelial lining fluid (ELF). This research highlights the role of ELF in NO2 uptake, suggesting reactive absorption mechanisms.
Area of Science:
- Pulmonary toxicology
- Environmental health
- Biochemistry
Background:
- Previous studies suggested pulmonary absorption of inhaled nitrogen dioxide (NO2) is reaction-limited.
- The epithelial lining fluid (ELF) is the primary site for NO2 absorption interactions.
Purpose of the Study:
- To investigate if ELF-NO2 interactions explain pulmonary NO2 reactive absorption.
- To compare NO2 uptake in rat ELF with a reduced glutathione (GSH) model system.
Main Methods:
- In vitro exposure of rat ELF (obtained via bronchoalveolar lavage) and GSH to NO2-air mixtures.
- Utilized constant gas flow and planar gas-liquid interfaces for exposures.
- Analyzed NO2 uptake rates, dependence on pH, concentration, and temperature.
Main Results:
- NO2 uptake by ELF was less affected by pH than GSH.
- Uptake was proportional to ELF concentration but did not saturate.
- Arrhenius plots indicated chemical reaction limitations in NO2 uptake by ELF and GSH.
Conclusions:
- Rat ELF's NO2 uptake rate is significantly influenced by chemical reactions.
- These findings support the hypothesis that reactive absorption mechanisms are critical in the lungs' response to NO2.