Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta T6G 2G3, Canada.
Chem Res Toxicol. 2013 Jun 17;26(6):952-62. doi: 10.1021/tx400123q. Epub 2013 Jun 4.
Arsenic speciation in blood can improve understanding of the metabolism and toxicity of arsenic. In this study, arsenic species in the plasma and red blood cells (RBCs) of arsenite-treated female F344 rats were characterized using anion exchange and size exclusion chromatography separation with inductively coupled plasma mass spectrometry (ICPMS) and electrospray ionization tandem mass spectrometry (ESI MS/MS) detection. Arsenite (iAs(III)), arsenate (iAs(V)), monomethylarsonic acid (MMA(V)), dimethylarsinic acid (DMA(V)), trimethylarsine oxide (TMAO(V)), monomethylmonothioarsonic acid (MMMTA(V)), and dimethylmonothioarsinic acid (DMMTA(V)) were detected in the plasma, with DMA(V) being the predominant metabolite. Upon oxidative pretreatment with 5% hydrogen peroxide (H2O2), plasma proteins released bound arsenic in the form of DMA(V) as the major species and MMA(V) as the minor species. The ratio of protein-bound arsenic to total arsenic decreased with increasing dosage of iAs(III) administered to the rats, suggesting a possible saturation of the binding capacity of the plasma proteins. The proportion of the protein-bound arsenic in the plasma varied among rats. In the H2O2-treated lysates of red blood cells of rats, DMA(V) was consistently found as the predominant arsenic species, probably reflecting the preferential binding of dimethylarsinous acid (DMA(III)) to rat hemoglobin. iAs(V), MMA(V), and trimethylarsine oxide (TMAO(V)) were also detected in the hydrogen peroxide-treated lysates of red blood cells. Importantly, DMMTA(V) and MMMTA(V) have not been reported in rat blood, and the present finding of DMMTA(V) and MMMTA(V) in the rat plasma is toxicologically relevant because these pentavalent thioarsenicals are more toxic than their counterparts DMA(V) and MMA(V). Identifying novel thiolated arsenicals and determining protein-bound arsenicals in the blood provide useful insights into the metabolism and toxicity of arsenic in animals.
砷形态分析可增进对砷代谢和毒性的理解。本研究采用阴离子交换和尺寸排阻色谱分离，结合电感耦合等离子体质谱（ICPMS）和电喷雾串联质谱（ESI-MS/MS）检测，分析了亚砷酸盐处理的雌性 F344 大鼠血浆和红细胞（RBC）中的砷形态。在血浆中检测到亚砷酸盐（iAs(III)）、砷酸盐（iAs(V)）、一甲基砷酸（MMA(V)）、二甲基砷酸（DMA(V)）、三甲基氧化砷（TMAO(V)）、一甲基单硫代砷酸（MMMTA(V)）和二甲基单硫代砷酸（DMMTA(V)），其中 DMA(V)是主要代谢产物。经 5%过氧化氢（H2O2）氧化预处理后，以 DMA(V)为主、MMA(V)为辅的形式从血浆蛋白中释放出结合砷。随给予大鼠的 iAs(III)剂量增加，蛋白结合砷与总砷的比值降低，提示血浆蛋白的结合能力可能达到饱和。不同大鼠的血浆蛋白结合砷比例存在差异。经 H2O2 处理的大鼠红细胞裂解液中，始终发现以 DMA(V)为主的砷形态，可能反映了二甲基砷酸（DMA(III)）与大鼠血红蛋白的优先结合。在 H2O2 处理的红细胞裂解液中还检测到 iAs(V)、MMA(V)和三甲基氧化砷（TMAO(V)）。重要的是，DMMTA(V)和 MMMTA(V)尚未在大鼠血液中报道，本研究在大鼠血浆中发现 DMMTA(V)和 MMMTA(V)具有毒理学意义，因为这些五价硫代砷比它们的对应物 DMA(V)和 MMA(V)毒性更大。鉴定新型硫代砷化物并确定血液中的蛋白结合砷，为了解动物体内砷的代谢和毒性提供了有用的见解。
