Rat Model to Investigate the Treatment of Acute Nitrogen Dioxide Intoxication

1 The pulmonary toxic events induced by acute nitrogen dioxide (NO)2 exposure were studied in the rat to develop an inhalation model to investigate therapeutic measures. 2 A good correlation was observed between the lung weights and severity of the atypical pneumonitis. The pulmonary effects observed, became more pronounced with increasing NO 2 concentrations (0, 25, 75, 125, 175 or 200 ppm, 1 ppm NO2=1.88 mg m-3 NO2) and exposure times (5, 10, 20 or 30 min). 3 An adequate NO 2 concentration is 175 ppm, because it can induce a severe lung injury without mortality. This makes it possible to investigate suitable therapeutic interventions for several days. 4 Following acute inhalatory NO2 intoxication, transformation of NO2 to nitrate is presumably more notable than transformation to nitrite. 5 The transformation of NO2 to nitrate in lung tissue causes a slight increase in the serum nitrite concentration, which does not induce measurable formation of methaemoglobin. 6 Presumably, methaemoglobin does not contribute to the toxicity of NO2 intoxication.