Arsenic speciation in bile and urine following oral and intravenous exposure to inorganic and organic arsenics in rats
Arsenic speciation in bile and urine following oral and intravenous exposure to inorganic and organic arsenics in rats
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DOI：
10.1093/toxsci/kfh265
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发表时间：
2004-12-01
影响因子：
3.8
通讯作者：
Hirano, S
中科院分区：
文献类型：
--
作者：
Cui, X;Kobayashi, Y;Hirano, S
尽管无机砷酸盐(iAs(V))和亚砷酸盐(iAs(III))在肝脏中代谢并排泄到胆汁和尿液中，但口服iAs后胆汁中的代谢物仍不清楚。雄性Sprague-Dawley大鼠口服（po）或静脉注射（iv）暴露于iAs和甲基化砷，并通过高效液相色谱-电感耦合氩等离子体质谱分析尿液和胆汁中的砷形态。砷会诱导多药耐药相关蛋白 2 (MRP2)，并且还测定了肝脏和胆汁中谷胱甘肽 (GSH) 水平的变化。代谢形态研究表明，在 iAs(III)- 或 iAs(V)-po 大鼠中，砷以甲基砷二谷胱甘肽 (MADG) 和/或二甲基砷酸 (DMA(V)) 形式排泄到胆汁中，但在 iAs(III)- 和 iAs(V)-iv 大鼠中，MADG 和砷三谷胱甘肽 (ATG) 是排泄到胆汁中的主要形式。在 MADG-po 大鼠中，MADG 以 MADG 和 DMA(V) 形式排泄到胆汁中。一甲基胂酸 (MMA(V))-和 DMA(V)-iv 大鼠不会将大量的 MMA(V) 或 DMA(V) 排泄到胆汁中，并且大部分以未改变的化学形式排泄到尿液中。综上所述，胆汁中检测到的 DMA(V) 大部分被认为是二甲基砷谷胱甘肽 (DMAG) 的解离。尿砷形态显示，在 iAs(III)-iv 大鼠中砷代谢为 43% 甲基化 DMA(V)、47% 非甲基化 iAs(III) 和 10% iAs(V)，而在 iAs(V)-iv 大鼠中仅检测到 3% 甲基化 DMA(V)、87% 非甲基化 iAs(V) 和 10% iAs(III)。砷的积累呈剂量依赖性，iAs(III)-po 大鼠肝脏中的砷浓度显着高于 iAs(V)-po 大鼠肝脏中的砷浓度。相对较高剂量的 iAs(V)-po 会降低胆汁中的 GSH 水平，但 iAs(III)- 或 iAs(V)-iv 会显着增加胆汁中的 GSH 水平。 iAs 暴露增加了肝脏中 MRP2 的表达。在 iAs-iv 大鼠中，用丁硫氨酸亚砜亚胺预处理主要抑制砷排泄到胆汁中。总之，我们的数据表明，胆汁和尿液中砷的排泄和形态受到砷给药途径、剂量和化学形式的影响，并且谷胱甘肽在砷代谢中起着关键作用。我们还首次证明，可能源自 DMAG 的 DMA(V) 在 iAs-po 大鼠中被排泄到胆汁中。
Although inorganic arsenate (iAs(V)) and arsenite (iAs(III)) are metabolized in liver and excreted into bile and urine, the metabolites in the bile after the oral intake of iAs remain unclear. Male Sprague-Dawley rats were orally (po) or intravenously (iv) exposed to iAs and methylated arsenics, and the arsenic speciation in the urine and bile was analyzed by high performance liquid chromatography-inductively coupled argon plasma mass spectrometry. Arsenic caused induction of multidrug resistance-associated protein 2 (MRP2), and changes of glutathione (GSH) levels in the liver and bile were also determined. The metabolic speciation studies revealed that arsenic was excreted into bile in the methylarsenic-diglutathione (MADG) and/or dimethylarsenic acid (DMA(V)) forms in iAs(III)- or iAs(V)-po rats, but that MADG and arsenic-triglutathione (ATG) are the main forms excreted into bile both in iAs(III)- and iAs(V)-iv rats. In MADG-po rats, the MADG was excreted into bile in the MADG and DMA(V) forms. Monomethylarsonic acid (MMA(V))- and DMA(V)-iv rats did not excrete significant amounts of either MMA(V) or DMA(V) into bile and mostly excreted into urine in the unchanged chemical forms. Taken together, the DMA(V) detected in the bile is mostly supposed to be the dissociation of dimethylarsenic-glutathione (DMAG). Urinary arsenic speciation showed that arsenic metabolized to 43% methylated DMA(V), 47% unmethylated iAs(III), and 10% iAs(V) in iAs(III)-iv rats, whereas only 3% methylated DMA(V), 87% unmethylated iAs(V), and 10% iAs(III) were detected in iAs(V)-iv rats. Arsenic was accumulated dose dependently, and arsenic concentration was significantly higher in the iAs(III)-po rat liver than in the iAs(V)-po rat liver. GSH levels in the bile were decreased by relatively higher doses of iAs(V)-po, but significantly increased by iAs(III)- or iAs(V)-iv. iAs-exposure increased the expression of MRP2 in the liver. Pretreatment with buthionine sulfoximine predominantly inhibited arsenic excretion into bile in iAs-iv rats. In conclusion, our data demonstrated that biliary and urinary arsenic excretion and speciation are affected by the route, dose, and chemical forms of arsenical administration, and GSH plays a key role in arsenic metabolism. We are also first to show that DMA(V) that probably originated from DMAG is excreted into the bile in iAs-po rats.