Korean Journal of Preventive Medicine 1999;32(1): 101-107.
Effects of Exposure to Hexavalent Chromium on the Level of 8-Hydroxydeoxyguanosine and the Activities of Superoxide Dismutase and 8-Hydroxyguanine Endonuclease in Rat Lung .
1Department of Preventive Medicine, College of Medicine, Chungbuk National University, Industrial Chemical Research Center, Industrial Health Research Institute. 2Department of Pharmacology, College of Medicine, Chungbuk National University, Industrial Chemical Research Center, Industrial Health Research Institute.
ABSTRACT
OBJECTIVES: To determine the effects of exposure to hexavalent chromium, 93 male Sprague-Dawley rats were exposed to hexavalent chromium solution. METHODS: Rats were divided into 4 groups and exposed to 0.1 ml of 0 mM, 0.4 mM, 2.0 mM, and 10.0 mM potassium chromate in the first experiment, and to 0.1 ml of 0 mM, 20 mM, 40 mM, and 80 mM in the second for consecutive 3 days by tracheal instillation. Three and 10 rats were the controls for the first and the second experiments, respectively. Lung tissues were then removed to measure the 8-hydroxydeoxyguanosine (8-OH-dG) level using the HPLC-ECD method, superoxide dismutase (SOD) activity using the cytochrome C method, and 8-hydroxyguanine endonuclease activity using the oligonucleotide nicking assay. RESULTS: The results showed no significant linear relationship between chromium exposure level and 8-OH-dG level or 8-hydroxyguanine endonuclease activity. In the first experiment, 8-OH-dG level and 8-hydroxyguanine endonuclease activity increased in 0.4 mM group, and then decreased in 2.0 mM and 10.0 mM groups. The correlation coefficients between 8-OH-dG level and 8-hydroxyguanine endonuclease activity was statistically significant (P<0.01), and total SOD activity was elevated by chromium exposure in a dose-dependent manner (P<0.05). In contrast, there was no significant dose-response pattern or correlation in the second experiment. CONCLUSIONS: Based on the fact that there was no linear relationship between chromium dose and 8-OH-dG level or activity of the repair enzyme, it seems unlikely that 8-OH-dG formation is the major mechanism of chromium carcinogenesis.
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