Trivalent arsenic (As(III)) exposure is linked to cancer, but exposure includes pentavalent arsenic (As(V)). These forms interconvert in biological systems, and the mechanism is not understood. Arsenic has a high affinity for sulfhydryls, and the interaction of As(III) and As(V) with biological sulfhydryls and cellular uptake was investigated in this study. Incubation of rat blood at 1 mM arsenic showed As(V) uptake, membrane and protein binding to be time dependant. These processes were almost immediate with As(III) incubation. Incubation at 25 mM As(V) resulted in 40% thiol depletion with no oxidized glutathione formation. Metabolite analysis showed half of the As(V) converted to As(III). In As(III) incubation, 27% thiol depletion occurred with 300% increase in GSSG. As(V) reduction combined with thiol depletion could indicate that arsenate used sulfhydryls as reducing equivalents. Because arsenate uptake was slow this reduction may not be a main contributor to the overall in vivo process.
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机译：三价砷（As（III））暴露与癌症有关，但暴露包括五价砷（As（V））。这些形式在生物系统中相互转换，其机理尚不清楚。砷对巯基具有很高的亲和力，本研究研究了As（III）和As（V）与生物巯基的相互作用和细胞摄取。在1 mM砷下孵育大鼠血液显示As（V）吸收，膜和蛋白质结合是时间依赖性的。 As（III）孵育几乎立即完成了这些过程。在25 mM As（V）下孵育会导致40％的巯基消耗，而不会形成氧化型谷胱甘肽。代谢物分析显示一半的As（V）转化为As（III）。在As（III）孵育中，发生了27％的硫醇消耗，GSSG增加了300％。 As（V）还原与巯基消耗结合可能表明砷酸盐使用巯基作为还原当量。由于砷酸盐的吸收缓慢，因此减少可能不是整个体内过程的主要贡献者。
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