Morphometric Analysis of Alveolar Responses of F344 Rats to Subchronic Inhalation of Nitric Oxide

In a follow-up study to previous research, Dr. Mercer and colleagues at Duke University exposed three groups of rats continuously for six weeks to 2 or 6 ppm nitric oxide (NO) or to filtered air to learn more about the toxicity of NO so as to compare it with two other important oxidants, ozone and nitrogen dioxide (NO₂). At the end of the exposure period he used an electron microscope to measure the number of holes in the alveolar septa and to observe other structural changes, such as in the surface area and the number and type of other abnormalities in the alveolar septa. The investigator also collected samples of fluid from the large and small airways and analyzed them for markers that would indicate inflammation and cell damage. He compared these results with those obtained previously in experiments using ozone and NO₂.