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  • 1
    ISSN: 1432-0738
    Keywords: Polychlorinated dibenzofurans (PCDFs) ; Aryl hydrocarbon hydroxylase (AHH) ; Enzyme induction ; Structure activity relationship ; Toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The aryl hydrocarbon hydroxylase (AHH) inducing potency of toxic chlorinated aromatic hydrocarbons such as polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was studied in the young male Wistar rats. Alternatively, a technical PCDF mixture, 15 individual PCDF isomers or TCDD were administered i.p. in doses of 5 μg/kg; a PCB mixture was given in a dose of 50 mg/kg. The order of AHH inducing ability was TCDD 〉 PCDFs ≫ PCBs in kidney, lung, and liver. In the prostate, thymus, and spleen, only TCDD enhanced the AHH activity. The AHH inducibility in the lung and liver, induced by 15 pure PCDF isomers with varying chlorine substitutions was also examined. Only 2,3,7,8-tetrachlorodibenzofuran (2,3,7,8-tetra-CDF) and 2,3,4,7,8-pentachlorodibenzofurans (2,3,4,7,8-penta-CDF) significantly induced the hepatic AHH activity (4- and 2-fold, respectively), while eight PCDF isomers, including these two, significantly enhanced the pulmonary AHH activity (6- to 30-fold). Taking into account both the potent AHH inducibility and the high bioaccumulation of these compounds, 2,3,7,8-tetra- and 2,3,4,7,8-penta-CDF should be given due attention with regard to environmental-related factors and the possibility of involvement in the etiology of “Yusho” disease.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0738
    Keywords: Key words Polychlorinated biphenyl ; Methylsulfonyl metabolite ; Gap junction intercellular communication ; IAR 20 rat liver epithelial cell
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of three polychlorinated biphenyl (PCB) congeners and their six methylsulfonyl (MeSO2)-metabolites on cell communication have been investigated in the scrape-loading/dye-transfer assay in IAR 20 rat liver epithelial cells. The results demonstrated that at non-cytotoxic concentrations 2,2′,4′,5-tetrachlorobiphenyl, 2,2′,4′,5,5′-pentachlorobiphenyl (2,2′,4′,5,5′-pentaCB), 2,2′,4′,5,5′,6-hexachlorobiphenyl (2,2′,4′,5,5′, 6-hexaCB), and their 3- and 4-MeSO2 derivatives completely inhibited the cell communication within 1 h. 4-MeSO2-2,2′,4′,5,5′-pentaCB and 4-MeSO2-2,2′,4′,5, 5′,6-hexaCB appeared to inhibit the cell communication at slightly lower concentration than their parental PCB congeners and 3-MeSO2 derivatives. The results show that 3- and 4-MeSO2 derivatives of the PCB congeners tested inhibit gap junction intercellular communication at about the same potency as their parental compounds. Since inhibition of cell communication is often observed after treatment with many tumor promoters, our findings suggest that the metabolites may also act as tumor promoters.
    Type of Medium: Electronic Resource
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