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INDUSTRIAL HEALTH 1990,28,151-157
Effect of Heptachlor on Hepatic Mitochondrial Oxidative
Phosphorylation in Rat
Tadamichi MEGURO, Fumio IZUSHI and Masana OGATA
Department of Public Health, Okayama University Medical School,
2-5-2, Shikatacho, Okayama City, Okayama 700, Japan
(Received May 1, 1990 and in revised form August 13, 1990)
Abstract: In a study of the hepatotoxicity of heptacholor (1,4,5,6,7,8,8-heptachloro 3a, 4,7,7 a-tetrahydro-4,7-methanoindene), a major compound of chlordane, the effect of heptachlor on the respiratory activity (oxidative phosphorylation and electron transport) of rat liver mitochondria was investigated. Heptachlor at a final concentration of 50 muM with succinate as subatrate decreased the respiratory control index (RCI) due to a marked inhibition of state 3 respiration and a slight inhibition of state 4 respiration. One hundred muM heptachlor with succinate as substrate suppressed the 3 and 4 respiration almost completely. On the other hand, heptacholor at a final concentration ranging from 50 to 100 muM with beta-hydroxybutylate (beta-HB) slightly decreased the RCI and decreased the RCI hardly at all with ascorbate plus N,N,N',N',-tetramethylphenylene diamine (TMPD) as substrate. Heptachlor at a concentration of 50 muM in the presence of succinate also decreased the ADP/O ratio of mitochondria. The mode of inhibition of succinate oxidation by heptacholor apparently is a noncompetitive inhibiton, as shown by Lineweaver-Burk plot.
Key words: Chlordane-Heptachlor-Mitochondria-Oxidative phosphorylation
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