guanosene 3’,5-monophosphate (cyclic GMP) and may play a role in tissue proliferation and tumoregenesis, as well as exert effects on ciliary function and mucosal secretion in lung tissue. Acute lung damage resulting from exposure to nitrogen dioxide at levels

Acute lung damage resulting from exposure to nitrogen dioxide at levels of 80 ppm for 3 hours has been reported by Langloss, et al. (28). Blank, et al. (9) exposed rats to levels of 15 to 40 ppm for up to 5 hours. Both of these groups reported alveolar damage with subsequent edema followed by hyperplasia or increased biosynthesis. The relevance of these types of exposure to smoking-related disease processes is unclear, however, since Norman and Keith (34) reported that nitrogen dioxide is present in cigarette smoke only in trace quantities.