Histamine of mouse lungs after single exposure to nitrogen dioxide.

Pulmonary histamine and the weight of lungs were studied in mice, exposed to a single one-hour effect of high concentrations of edemagenic gas nitrogen dioxide in a metabolic chamber. Nitrogen dioxide concentrations were chosen according to the results of nitrogen dioxide analysis of the mining atmosphere immediately after the mining blasts. The results were estimated by the method of paired comparison with the findings registered in mice, exposed to the effect of air atmosphere under identical experimental conditions. The intervals following immediately the exposure and 5 hours after were chosen for the evaluation, with regard to the dynamics of the early and late stages of hypersensitivity of the first type. i) Immediately after the exposure to the concentrations of 43, 250, 387 and 540 mg.m-3, no significant differences were observed in the amount of pulmonary histamine. In concentrations higher than 43 mg.m-3, the weight of lungs increased (the proportion of pulmonary water and the dry tissue). ii) Five hours after the exposure (nitrogen dioxide concentrations 66, 130, 137 and 270 mg.m-3), pulmonary histamine decreased, at the concentration of 137 mg.m-3 in a significant way, on the other hand, it increased significantly at the concentration of 270 mg.m-3. Both concentrations higher than 130 mg.m-3 manifested an increased weight of lungs (increased proportion of dry tissue and pulmonary water). The obtained data do not allow to establish unambiguously the part of histamine on the pulmonary changes following the effect of nitrogen dioxide. The edemagenic effect of nitrogen dioxide estimated after one-hour influence can be considered as reversible up to five hours after the exposure in concentrations lower than 130 mg.m-3. The metodical part of the study gives detailed description of exposure technique and it brings a survey of methods of histamine determination in blood and tissues.