Influence of exposure regimen on nitrogen dioxide-induced morphological changes in the rat lung

Journal Article · Mon Dec 01 00:00:00 EST 1986 · Environ. Res.; (United States)

DOI:https://doi.org/10.1016/S0013-9351(86)80141-4· OSTI ID:6905162

Rombout, P J.A.; Dormans, J A.M.A.; Marra, M; van Esch, G J

Experiments were performed to study the influence of concentration, exposure pattern, and length of exposure on the degree and extent of morphological alterations in the NO/sub 2//sup -/ exposed rat lung. Four weeks of continuous exposure to 20 mg NO/sub 2//m/sup 3/ consecutively revealed damage and loss of cilia, replacement of desquamated type I pneumocytes by type II pneumocytes resulting in a cuboidal epithelial lining, an influx of alveolar macrophages, and hypertrophy and hyperplasia of the bronchiolar epithelium. The animals recovered almost completely from the induced lesions within 8 days. Continuous exposure to 1, 2.5, or 5 mg/m/sup 3/ displayed minimal alterations in the 5 mg/m/sup 3/ group. The effects increased with exposure time. Intermittent or continuous exposure to 20 mg NO/sub 2//m/sup 3/ resulted in minor differences after 4 weeks. The onset of the lesions was delayed and the massive influx of alveolar macrophages in the continuously exposed animals failed to appear in the intermittently exposed animals. This work demonstrates that in subacute experiments: (1) Concentration plays a more important role in inducing pulmonary lesions than exposure time when the product of concentration and time is kept constant. This effect is stronger during intermittent exposure than during continuous exposure. (2) Continuous exposure seems to be a more important factor with regard to a macrophage response than intermittent exposure. (3) The rat lung has a large capacity to repair almost completely from damage caused by short-term NO/sub 2/ exposure.

• Research Organization: National Institute of Public Health and Environmental Hygiene, Bilthoven, Netherlands
• OSTI ID: 6905162
• Journal Information: Environ. Res.; (United States), Vol. 41:2
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
LUNGS
MORPHOLOGICAL CHANGES
NITROGEN DIOXIDE
TOXICITY
BIOLOGICAL REPAIR
CHRONIC EXPOSURE
DOSE-RESPONSE RELATIONSHIPS
RATS
TIME DEPENDENCE
ANIMALS
BIOLOGICAL RECOVERY
BODY
CHALCOGENIDES
MAMMALS
NITROGEN COMPOUNDS
NITROGEN OXIDES
ORGANS
OXIDES
OXYGEN COMPOUNDS
RECOVERY
REPAIR
RESPIRATORY SYSTEM
RODENTS
VERTEBRATES
560300* - Chemicals Metabolism & Toxicology