Curriculum in Toxicology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Metallomics. 2011 Dec;3(12):1347-54. doi: 10.1039/c1mt00095k. Epub 2011 Oct 21.
Chronic ingestion of water containing inorganic arsenic (iAs) has been linked to a variety of adverse health effects, including cancer, hypertension and diabetes. Current evidence suggests that the toxic methylated trivalent metabolites of iAs, methylarsonous acid (MAs(III)) and dimethylarsinous acid (DMAs(III)) play a key role in the etiology of these diseases. Both MAs(III) and DMAs(III) have been detected in urine of subjects exposed to iAs. However, the rapid oxidation of DMAs(III) and, to a lesser extent, MAs(III) in oxygen-rich environments leads to difficulties in the analysis of these metabolites in samples of urine collected in population studies. Results of our previous work indicate that MAs(III) and DMAs(III) are relatively stable in a reducing cellular environment and can be quantified in cells and tissues. In the present study, we used the oxidation state-specific hydride generation-cryotrapping-atomic absorption spectroscopy (HG-CT-AAS) to examine the presence and stability of these trivalent metabolites in the liver of mice and in UROtsa/F35 cells exposed to iAs. Tri- and pentavalent metabolites of iAs were analyzed directly (without chemical extraction or digestion). Liver homogenates prepared in cold deionized water and cell culture medium and lysates were stored at either 0 °C or -80 °C for up to 22 days. Both MAs(III) and DMAs(III) were stable in homogenates stored at -80 °C. In contrast, DMAs(III) in homogenates stored at 0 °C began to oxidize to its pentavalent counterpart after 1 day; MAs(III) remained stable for at least 3 weeks under these conditions. MAs(III) and DMAs(III) generated in UROtsa/F35 cultures were stable for 3 weeks when culture media and cell lysates were stored at -80 °C. These results suggest that samples of cells and tissues represent suitable material for the quantitative, oxidation state-specific analysis of As in laboratory and population studies examining the metabolism or toxic effects of this metalloid.
慢性摄入含无机砷 (iAs) 的水与多种健康不良影响有关，包括癌症、高血压和糖尿病。目前的证据表明，iAs 的有毒三价甲基化代谢物，即甲基胂酸 (MAs(III)) 和二甲基胂酸 (DMAs(III))，在这些疾病的病因学中起着关键作用。在接触 iAs 的受试者的尿液中已经检测到了 MAs(III) 和 DMAs(III)。然而，在富含氧气的环境中，DMAs(III) 会迅速氧化，而 MAs(III) 的氧化程度较小，这导致在人群研究中收集的尿液样本中分析这些代谢物变得困难。我们之前的工作结果表明，MAs(III) 和 DMAs(III) 在还原细胞环境中相对稳定，可以在细胞和组织中进行定量。在本研究中，我们使用氧化态特异性氢化物发生-冷冻捕集-原子吸收光谱法 (HG-CT-AAS) 来检测 iAs 暴露的小鼠肝脏和 UROtsa/F35 细胞中这些三价代谢物的存在和稳定性。直接分析了 iAs 的三价和五价代谢物（无需化学提取或消化）。在冷去离子水中和细胞培养液中制备的肝匀浆，并在 0°C 或-80°C 下储存长达 22 天。DMAs(III)在-80°C 下储存的肝匀浆中稳定。相比之下，在 0°C 下储存的肝匀浆中 DMAs(III) 在 1 天后开始氧化为其五价对应物；在这些条件下，MAs(III) 至少稳定 3 周。在-80°C 下储存时，UROtsa/F35 培养物中生成的 MAs(III) 和 DMAs(III) 在 3 周内稳定。这些结果表明，细胞和组织样本代表了用于在实验室和人群研究中对这种类金属的代谢或毒性作用进行定量、氧化态特异性分析的合适材料。
