Lesion of the Lung in Rats Continuously Exposed to Two Parts Per Million of Nitrogen Dioxide

Abstract

Rats exposed continuously to 2 ppm ot nitrogen dioxide in air survived their ordinary lifetimes with persistent tachypnoea and usually died of nonpulmonary diseases. Resistance to airflow and dynamic compliance were not different from those in controls. Terminal and respiratory bronchiolar epithelium was affected mainly by a loss of exfoliative activity, reduced blebbing of cytoplasm into the airways, reduction in or loss of cilia, and the appearance of rod-shaped intracytoplasmic crystalloid inclusions. Morphologic evidence suggests that rats exposed to 2 ppm would have reduced cleansing function of the periphery of the lung. Pulmonary tissue was embedded in plastic and sections were cut at 1μ for light microscopy and thinner sections for electron microscopy.