Metabolic reduction of chromium as a threshold mechanism limiting its in vivo activity
| Autor: | Silvio De Flora, F.L. Petrilli |
|---|---|
| Rok vydání: | 1988 |
| Předmět: |
Chromium
Environmental Engineering chemistry.chemical_compound In vivo Parenchyma Biotransformation Carcinogens metabolism Chromium metabolism/pharmacokinetics/toxicity Humans Oxidation-Reduction Humans Environmental Chemistry Enzyme inducer Hexavalent chromium Waste Management and Disposal Biotransformation chemistry.chemical_classification biology Chemistry Glutathione respiratory system Pollution Cytosol Enzyme Biochemistry metabolism/pharmacokinetics/toxicity Carcinogens biology.protein Microsome metabolism Oxidation-Reduction |
| Zdroj: | Science of The Total Environment. 71:357-364 |
| ISSN: | 0048-9697 |
| DOI: | 10.1016/0048-9697(88)90208-2 |
| Popis: | Various mechanisms tend to reduce hexavalent chromium (Cr(VI)) in the organism, both outside and inside target cells. A reducing activity has been demonstrated in the blood (mainly in erythrocytes), in secretions of the alimentary tract (saliva, gastric juice) and in the lumen of terminal airways (epithelial-lining fluid and alveolar macrophages). Preparations of several types of cells from various animal species - including human liver, lung parenchyma and bronchial tree cells - are capable of metabolically reducing Cr(VI) to a variable extent. This process can be ascribed to different cytoplasmic components, e.g. to mitochondria, microsomal fractions and especially to cytosolic fractions, where reduction is partly due to electron donors (e.g. glutathione) and mainly to NADPH-dependent enzyme activities, such as DT-diaphorase. Reduction is not only selectively stimulated by enzyme inducers but also, in rat lung cells, by the repeated intra-tracheal administration of Cr(VI) itself. All these reducing reactions are interpreted as detoxifying mechanisms, which constitute a threshold phenomenon in chromium carcinogenesis. |
| Databáze: | OpenAIRE |
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