title: Effects of ammonium nitrate aerosol exposure on lung structure of normal and elastase-impaired rats and guinea pigs.
abstract: Groups of rats and guinea pigs with normal lungs and others with elastase-induced emphysema were exposed to NH4NO3 aerosols of 0.60 mass median aerodynamic diameter at 1 mg/m3 for 6 hr/day, 5 days/week, for 4 weeks. Morphologic and morphometric studies were performed on lungs perfused with cacodylate-buffered 2% glutaraldehyde under 20 cm H2O pressure at necropsy. The tissues were studied for pathologic change by light and electron microscopy; emphysema was evaluated by subgross and microscopic methods, including changes in mean alveolar chord length using scanning electron microscopy techniques. Elastase produced emphysema to a degree quantifiable by all criteria studied; however, it apparently obscured the effects of nitrate inhalation. The NH4NO3 exposure (compared to air alone) tended to increase values for pulmonary parameters in normal animals of both species and to decrease them in elastase-treated animals. The NH4NO3 exposure increased values for lung volume in rats, percentage area affected in elastase-treated rats, and chord length beta in normal animals of both species. The responses to NH4NO3 were slight (P less than 0.10) and were not accompanied by any detectable changes in alveolar structure. Therefore, the effects of NH4NO3 at this exposure level and duration, are regarded as biologically insignificant for rats and guinea pigs.
mesh_terms: D000336:Aerosols / Q000633:toxicity*; D000818:Animals; D004646:Emphysema / Q000139:chemically induced; D006168:Guinea Pigs; D008168:Lung / Q000187:drug effects*; D008297:Male; D008854:Microscopy, Electron; D008855:Microscopy, Electron, Scanning; D009566:Nitrates / Q000633:toxicity*; D010196:Pancreatic Elastase / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000336:Aerosols; D009566:Nitrates; D010196:Pancreatic Elastase; C006568:ammonium nitrate