A comparison of terminal airway remodeling in chronic daily versus episodic ozone exposure

Journal Article · Fri Nov 30 23:00:00 EST 1990 · Toxicology and Applied Pharmacology; (USA)

DOI:https://doi.org/10.1016/0041-008X(90)90335-R· OSTI ID:6208250

Barr, B C; Hyde, D M; Plopper, C G; Dungworth, D L ^[1]

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1. Univ. of California, Davis (USA)

This study compares centriacinar changes by ultrastructural morphology and morphometry following daily versus episodic ozone exposure in rats. Three groups of rats were exposed to air, 0.95 ppm ozone 8 hr daily for 90 days, and 0.95 ppm ozone 8 hr daily in seven successive 5-day episodes separated by 9-day recovery periods for a total of 89 days. Sections from the left lung and dissected acini from the right middle lobe were studied by light and electron microscopy. The centriacinar lesion following episodic exposure was similar but diminished in severity compared to that of rats exposed daily. Damage following episodic exposure appeared to be more than predicted by an exposure regimen which delivered 35% of the total ozone dose during daily exposure. The total volume of affected parenchyma was similar following both exposures. Respiratory bronchiole formation increased following both exposures but this was only statistically significant following daily exposure. The most severe epithelial damage was at the tips of alveolar septa in alveolar ducts distal to the respiratory bronchiole. Interstitial thickness in the injured respiratory bronchiole and proximal alveolar duct increased significantly and similarly following both exposures. Epithelium along the respiratory bronchiole of daily exposed rats was more differentiated. In the episodic group, respiratory bronchiole and alveolar duct epithelium consisted of a range of intermediate, less differentiated bronchiolar or alveolar epithelial cells. The episodic exposure resulted in a diminished lesion, but there appears to be some cumulative effect of repeated exposures with respiratory bronchiolar and alveolar duct epithelium in a more dynamic state of injury and repair.

• OSTI ID: 6208250
• Journal Information: Toxicology and Applied Pharmacology; (USA), Journal Name: Toxicology and Applied Pharmacology; (USA) Vol. 106:3; ISSN TXAPA; ISSN 0041-008X
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL TISSUES
ANIMALS
BODY
COMPARATIVE EVALUATIONS
EPITHELIUM
INHALATION
INTAKE
LUNGS
MAMMALS
ORGANS
OZONE
PATHOLOGICAL CHANGES
RATS
RESPIRATORY SYSTEM
RODENTS
TISSUES
TOXICITY
VERTEBRATES