title: Pulmonary function in juvenile and young adult rats exposed to low-level NO2 with diurnal spikes.
abstract: Pulmonary function was examined for juvenile and young adult Fischer 344 rats that were continuously exposed to NO2 (0.5, 1.0, or 2.0 ppm) for up to 6 wk. The exposure included twice daily 1-h spikes equal to 3 times the baseline concentration. This spike-to-baseline ratio was chosen to simulate morning and evening urban rush-hour conditions. Juvenile rats were examined after 3 and 6 wk of NO2 exposure, whereas young adult rats were examined after 1-, 3-, and 6-wk intervals. Lung volumes, compliance, and efficiency of ventilation distribution were evaluated. Lung volumes increased in the juvenile rats after 3- and 6-wk exposures to 1.0 and 2.0 ppm NO2, but were unchanged in young adult rats. Lung compliance increased in juvenile rats exposed to 1.0 or 2.0 ppm NO2 for 3 wk. However, it was unchanged in juvenile rats exposed for 6 wk or in young adult rats exposed for 1 or 3 wk. Compliance decreased in young adult rats exposed to 2.0 ppm NO2 for 6 wk and was correlated to an overall thickening of alveolar interstitium and septal tissue. However, the observed changes in pulmonary function were marginal and reversible, since lung-function measurements were not different from controls after a 3-wk recovery period.
authors.affiliation: Northrop Services, Inc.-Environmental Sciences, Research Triangle Park, North Carolina 27709.
authors.forename: M A
authors.initials: MA
authors.lastname: Stevens
authors.forename: M G
authors.initials: MG
authors.lastname: Ménache
authors.forename: J D
authors.initials: JD
authors.lastname: Crapo
authors.forename: F J
authors.initials: FJ
authors.lastname: MIller
authors.forename: J A
authors.initials: JA
authors.lastname: Graham
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D008168:Lung / Q000187:drug effects* / Q000502:physiology; D008170:Lung Compliance / Q000187:drug effects; D008297:Male; D009585:Nitrogen Dioxide / Q000633:toxicity*; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D009585:Nitrogen Dioxide