Nitrogen dioxide-induced emphysema in rabbits.

Abstract

Rabbits were exposed to 8 to 12 ppM NO/sub 2/ for 3 to 4 months. Lungs of exposed rabbits were enlarged, non-collapsable with irregular surfaces, and crumbly when cut after drying. Abnormally dilated air-spaces were revealed by microscopic examination. The bronchiolar epithelium was hypertrophied and hyperplastic. There were increased macrophages, epithelium cells, and connective tissue at the junction of bronchiole and alveolar duct. Alveolar ducts were larger, but alveoli size was nonuniform. There were larger and more numerous elastic fibers in the walls of peripheral air spaces. There was regression of symptoms with recovery (1 wk to 1 mo), but peripheral air spaces remained enlarged and alveolar ducts were larger as were elastic fibers. These findings meet the current definition of emphysema.