代谢
六价铬化合物是人类呼吸道的已知致癌物。尽管人们正在寻找六价铬化合物在细胞转化中的作用，但其机制尚未完全了解。这项研究的目的是确定人类细胞在体外接触可溶性或颗粒状铬化合物后铬价态的分布。本研究使用同步辐射X射线微探针来研究细胞对Cr(VI)的还原作用，并成像细胞中的铬氧化态。研究显示，可溶性Cr(VI)化合物在细胞中完全还原为Cr(III)。Cr(III)在细胞体积内均匀分布，因此存在于细胞核内。在低溶解度颗粒状铬酸盐的情况下，Cr(VI)可以与细胞内和细胞核内的Cr(III)一起存在于细胞环境中，作为细胞核周围的颗粒。化学分布图还表明，细胞内Cr(III)源于外部溶解和还原铅铬酸盐，而不是源自细胞内吞噬的颗粒。低溶解度铬酸盐与可溶性铬酸盐相比可能的更强致癌性可能源于细胞核内Cr(III)的遗传毒性效应和持续暴露于强氧化剂Cr(VI)的组合。/可溶性和颗粒状铬酸盐/
Hexavalent chromium compounds are known carcinogens for the respiratory tract in humans. The mechanism of cell transformation by hexavalent chromium compounds is not fully understood although a role for intracellular reduction is sought. The aim of this study was to determine the distribution of Cr valence states in human cells after in vitro exposure to soluble or particulate chromium compounds. A synchrotron X-ray-based microprobe was used to investigate the cellular reduction of Cr(VI) and to image chromium oxidation states in cells. It was shown that soluble Cr(VI) compounds are fully reduced to Cr(III) in cells. Cr(III) is homogeneously distributed within the cell volume and therefore present within the nucleus. In the case of low solubility particulate chromate compounds, Cr(VI) can coexist in the cell environment, as particles in the perinuclear region, together with intracellular and intranuclear Cr(III). Chemical distribution maps also suggest that intracellular Cr(III) originates from extracellular dissolution and reduction of lead chromate rather than from intracellular engulfed particles. The possible stronger carcinogenicity of low solubility chromate vs soluble chromate compounds may derive from the combinative genotoxic effects of intranuclear Cr(III) and the persistent exposure to a strong oxidant, Cr(VI). /Soluble and particulate chromates/
来源:Hazardous Substances Data Bank (HSDB)
