Promoting Effect of Sodium Chloride Solution Mist on the Induction of Papillomas on Syrian Hamster Tracheal Mucosa Following Administration of Diethylnitrosamine

The promoting effect of NaCI solution mist was studied in the induction of papillomas on Syrian hamster trachea following single subcutaneous injection of diethylnitrosamine (DEN). Sixty male hamsters were divided into three groups. Group A; Exposure to a 5% NaCl solution mist for 32 weeks following single subcutaneous injection of DEN at a dose of 3 mg/100 g body weight. Group B; Subcutaneous DEN injection alone. Group C; Exposure to the NaCI mist for 32 weeks alone. Total numbers of papillomas on the trachea in each group were 107 in group A, 64 in group B, and 0 in group C (P0.05 between group A and B, P<0.01 between either groups A or B and C). Comparing the incidence of large papillomas with a diameter of more than 2 mm, that in group A hamsters was significantly greater than that of group B (22 large papillomas vs. 8 large papillomas, P<0.01). No difference in the effects on the epithelial cells of the nasal cavity, the bronchial or the alveolar cells in the lung was recognized between groups A and B. The hamsters in group C were not observed to have any changes in any of the respiratory organs. Inhalation of NaCI solution mist is considered to have a promoting effect on the induction of papillomas in the hamster trachea following DEN injection.