Long-Term Nitrogen Dioxide Exposure

Abstract

Male Long Evans hooded rats were chronically exposed to an average 2.9 ppm (±0.71 SD) of nitrogen dioxide 24 hours each day, five days a week for nine months. The major effects of NO₂ were a significant 12.7% increase in lung wet weight, a 13.0% decrease in lung compliance, and a significant reduction in surface-active properties of the lung wash. The NO₂-exposed lungs also revealed a significant 8.7% decrease in lung lipid content and a marked decrease in percentage of total saturated phospholipid fatty acids. This reduction in saturation was due almost entirely to a decrease in the percentage of palmitic acid. The suggestion is made that alterations in lung lipid metabolism may be the underlying mechanism which leads to some of the pulmonary effects following long-term exposure to subacute levels of NO₂.