nitrogen-dioxide and Adenoma

The long-term effects of sodium nitrite (NaNO2) on carcinogenesis induced by urethane (total dose 1.0 mg/g body weight) in low-grade cancer F1 (C57BLxCBA) and high-grade A/Snell mice and on viral (Rausher leukemia virus) leukomogenesis in Balb/c mice. The murine intake of NaNO2 with water (50 mg/l) causes a statistically significant increase in the number of adenomas in the lung. Examining the mechanism of conversion of NO2- to NO led to the assumption that the free radical compounds NO and NO2 are involved in the potentiating action of NO2 on blastomogenesis. The use of the oxidant emoxypine (3-hydroxypyridine) confirmed the above. The role of NO and NO2 in the intracellular processes under the modifying effects of nitrites and nitrates on blastomogenesis is analyzed.

Topics: Adenoma; Animals; Antioxidants; Carcinogenicity Tests; Female; Leukemia Virus, Murine; Leukocytes; Lung; Lung Neoplasms; Lymphocyte Activation; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Neoplasms, Experimental; Nitric Oxide; Nitrites; Nitrogen Dioxide; Oxidants, Photochemical; Picolines

The promoting effects of a combined exposure to two pollutants (NO2, O3 or H2SO4-aerosol) at near ambient levels on lung tumorigenesis induced by N-bis(2-hydroxypropyl) nitrosamine (BHPN) were investigated in male Wistar rats. The rats were given a single intraperitoneal injection of BHPN (0.5 g per kg body wt.) at 6 weeks of age. They then were exposed to clean air, 0.05 ppm O3 (mean concentration for 10 h/day; 0.1 ppm peak concentration), 0.05 ppm O3 (mean concentration for 10 h/day; 0.1 ppm peak concentration) + 0.4 ppm NO2 or 0.4 ppm NO2 + 1 mg/m3 of H2SO4-aerosol for 13 months and were then maintained in a clean room for another 11 months. Room control animals were kept after injection of BHPN in a clean room for 24 months. The incidence of primary lung tumors in rats exposed to 0.05 ppm O3, 0.05 ppm O3 + 0.4 ppm NO2 and 0.4 ppm NO2 + 1 mg/m3 of H2SO4-aerosol with BHPN treatment was 8.3% (3 out of 36 rats), 13.9% (5 out of 36 rats) and 8.3% (3 out of 36 rats), respectively. The tumors were adenomas and adenocarcinomas. The incidence of adenomas was 2.8% (1 out of 36 rats) in the O3 alone group, 11% (4 out of 36 rats) in O3 + NO2 group and 5.6% (2 out of 36 rats) in NO2 + H2SO4 group. The incidence of adenocarcinomas was 5.6% (2 out of 36 rats) in the O3 group, 2.8% (1 out of 36 rats) in O3 + NO2 group and 2.8% (1 out of 36 rats) in NO2 + H2SO4 group. No lung tumors were found in the rats exposed to clean air with BHPN treatment and in animals not given BHPN but exposed to each air pollutant. The difference in tumor incidence between the clean air group with BHPN and the O3 + NO2 group with BHPN was statistically significant. The results show that exposure to O3 alone enhances tumor development and that the combined exposure to O3 or H2SO4 with NO2 produces an additional increase in incidence of lung tumor, respectively. The incidence of slight-moderate to marked alveolar cell hyperplasia in the groups exposed to each air pollutant with BHPN treatment was higher than that in the groups exposed to clean air with BHPN. Exposure to each air pollutant had no effect on the development of bronchiolar mucosal hyperplasia in lungs of rats treated with BHPN.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Adenocarcinoma; Adenoma; Aerosols; Animals; Carcinogens; Injections, Intraperitoneal; Lung Neoplasms; Male; Nitrogen Dioxide; Nitrosamines; Ozone; Rats; Rats, Inbred Strains; Sulfuric Acids

Lipid peroxide production, antioxidant contents and activities of antioxidative protective enzymes were examined in lungs of rats exposed to clean air (control group), 0.05 ppm O3, 0.05 ppm O3 + 0.04 ppm NO2 and 0.05 ppm O3 + 0.4 ppm NO2 for 22 months. The results were compared with our previous data in rats exposed to 0.04 ppm NO2, 0.4 ppm NO2 and 4 ppm NO2 for their life span (Sagai et al., Toxicol. Appl. Pharmacol., 73, (1984) 444-456). TBA values used as an index of lipid peroxidation in the lungs were increased maximally at 9 months, but were decreased below control values in animals exposed for 18 and 22 months. Nonprotein sulfhydryl (NPSH) contents were increased maximally at 9 months, and after 18 and 22 months were decreased significantly below control values. Vitamin E (VE) contents showed a similar trend. On the other hand, enzyme activities of glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), glutathione reductase (GR), glutathione peroxidase measured by using cumene hydroperoxide (cum.OOH) substrate (GPx-cum.OOH), glutathione peroxidase measured by using H2O2 as a substrate (GPx-H2O2), glutathione S-transferase (GSH-Tase) and superoxide dismutase (SOD) did not show any significant changes during this experiment. The results show that lipid peroxidation in lungs was increased synergistically by a combination of NO2 and O3 at ambient levels, and that the time of maximum lipid peroxide production was shorter than with NO2 alone. The protective ability against lipid peroxides was higher with increased lipid peroxide levels, but the inducibility was not maintained through a life span exposure to the combined gases. Additionally, two small adenomas were observed in 2 out of 18 rats in the 0.05 ppm O3 + 0.04 ppm NO2 group and a large adenoma was observed in 1 out of 18 animals in the 0.05 ppm + 0.4 ppm NO2 group exposed for 22 months.

Topics: Adenoma; Administration, Inhalation; Animals; Atmosphere Exposure Chambers; Breath Tests; Dose-Response Relationship, Drug; Drug Interactions; Lipid Peroxidation; Lung; Lung Neoplasms; Male; Nitrogen Dioxide; Organ Size; Ozone; Rats; Rats, Inbred Strains; Thiobarbiturates

The effects of nitrogen dioxide (NO2) on promotion of lung tumorigenesis induced by N-bis(2-hydroxypropyl) nitrosamine (BHPN) were investigated in male Wistar rats. In a preliminary study, the highest non-effective dose of BHPN was found to be 0.5 g per kg body weight. Rats were given a single intraperitoneal injection of BHPN at a dose of 0.5 g per kg body weight or saline at 6 weeks of age, and then exposed to clean air, 0.04 ppm, 0.4 ppm or 4 ppm of NO2 for 17 months, respectively. The incidence of pulmonary tumors in rats exposed to BHPN plus 4 ppm of NO2 was 12.5%; the tumors were adenomas and adenocarcinomas. Adenomas were found in 4 out of 40 rats (10%) and adenocarcinomas were found in 1 out of 40 rats (2.5%). The tumor incidence in the lungs of rats kept in BHPN plus clean air and BHPN plus 0.04 ppm of NO2 was 2.5% (1/40). In both groups adenomas were found. There was no significant difference in tumor incidence between animals exposed to BHPN plus clean air and to BHPN plus 4 ppm of NO2. No lung tumors were found in the group of BHPN plus 0.4 ppm NO2 and in animals exposed to NO2 without BHPN treatment. A high incidence of alveolar cell hyperplasia was observed in the lungs of rats injected with BHPN, and the effect of NO2 on development of alveolar cell hyperplasia was slight. On the other hand, marked bronchiolar mucosal hyperplasia was found in 17 out of 40 rats (42.5%) in the group of BHPN plus 4 ppm of NO2, and in 1 out of 40 rats (2.5%) in each of the group exposed to clean air, 0.04 ppm or 0.4 ppm of NO2 with BHPN treatment, respectively. The hyperplasia in lungs of rats exposed to 4 ppm of NO2 without BHPN treatment was slighter than that in lung of rat exposed to 4 ppm of NO2 with BHPN treatment. On the other hand, tumor incidence in the nasal cavity of rats in each of group exposed to clean air and NO2 with BHPN treatment was 97-100%. Incidence of tumors in other organs in the groups exposed to clean air and NO2 with and without BHPN treatment was very low, and NO2 had no effect on tumor development in the nasal cavity and other organs whether animals were treated with BHPN or not.(ABSTRACT TRUNCATED AT 400 WORDS)

Topics: Adenocarcinoma; Adenoma; Animals; Carcinogens; Lung; Lung Neoplasms; Male; Nitrogen Dioxide; Nitrosamines; Nose Neoplasms; Rats; Rats, Inbred Strains

Strain A/J mice were exposed by inhalation for 6 h/d, 5 d/wk, for 6 mo to carbon disulfide, 1,2-dibromoethane, ethylene oxide, naphthalene, nitrogen dioxide, or vinyl chloride. Significant increases in pulmonary adenoma formation were observed following exposure to 300 ppm carbon disulfide; 20 and 50 ppm 1,2-dibromoethane; 70 and 200 ppm ethylene oxide; 10 ppm nitrogen dioxide; and 50, 200, and 500 ppm vinyl chloride compared to control animals. Repeated studies with 1,2-dibromoethane, ethylene oxide, and vinyl chloride gave similarly significant results. Exposure of mice to 30 ppm naphthalene did not elicit a significant adenoma response. Histopathological examination of lungs from animals in these studies revealed multiple alveolar adenomas. Results from earlier studies with these chemicals, using strain A mice and Swiss mice, and bioassay information with rats and mice were compared with these data. These results provide further information for the validation of this in vivo model as a tool for predicting oncogenic potential following chemical exposure.

Topics: Adenoma; Animals; Carbon Dioxide; Carcinogens; Ethylene Dibromide; Female; Lung Neoplasms; Male; Mice; Mice, Inbred A; Naphthalenes; Nitrogen Dioxide; Vinyl Chloride

Topics: Adenoma; Air Pollution; Animals; California; Carbon Monoxide; Carcinogens; Dust; Hydrocarbons; Lung Neoplasms; Mice; Neoplasms, Experimental; Nitric Oxide; Nitrogen Dioxide; Ozone