Effects of subchronic inhalation of low concentrations of nitrogen dioxide. I. The proximal alveolar region of juvenile and adult rats.

摘要: Abstract Inhalation of nitrogen dioxide (NO 2 ) produces injury to the epithelium terminal airways and alveoli proximal airways. Techniques were devised isolate alveolar tissue from this region for morphometric studies define extent septal caused by NO . One-day-old six-week-old rats exposed either room air or 0.5 ppm 23 hr per day 7 days week 6 weeks. An additional group 6-week-old 2.0 same duration. Two daily hour spikes three times background concentrations (0.5 1.5 6.0 ppm) applied Monday through Friday. At end exposure, rat lungs fixed intratracheally infusing buffered 2% glutaraldehyde. Pieces lung embedded in large plastic blocks which softened with heat thin (0.3 mm) sliced. Terminal bronchioles their corresponding regions identified slices, removed, glued cylindrical EM sectioning. Morphometric analysis revealed that epithelial occurred all animals. The juvenile had been since 1 age exhibited changes characteristics type II cells. These cells spread cover more surface became thinner. Adult animals showed macrophages interstitium addition epithelium. Animals spreading hypertrophy Those higher concentration similar an increase I cell number. smaller covered less area than normal cells, suggesting a regenrating population results suggest prolonged exposure low can cause indicated initially followed differentiation into compensate repair injury. as sensitive rats.