CYTOLOGIC RESPONSE OF POSTNATAL RAT LUNGS TO O3 OR NO2 EXPOSURE

  • 1 January 1978
    • journal article
    • research article
    • Vol. 93  (1) , 183-+
Abstract
At the level of exposure employed (approximately 14.0 ppm NO2 or 0.85 ppm O3) epithelial cells at the juncture of the terminal airways and proximal alveoli have previously been shown to be seriously injured or destroyed in maturing (35 days of age or older) and adult lungs. Subsequent repair results in the formation of a tissue nodule at this location. Postnatal rats between birth and weaning were highly resistant to the cytotoxic effects of both NO2 and O3. Prior to weaning, exposure to O3 resulted in little or no injury when examined with either the light microscopy or EM, and only minor injury and loss of cilia from epithelial cells lining the terminal airways was noted after NO2 exposure. Subsequent to weaning at 20 days of age, there was a progressive increase in the cellular response in both the terminal airways and proximal alveoli after exposure to either oxidant gas. A plateau in the response is reached at approximately 35 days of age and continues until the animals are approximately 1 yr old. The data are discussed in terms of current theories on endogenous antioxidant mechanisms.