不同价态无机砷染毒大鼠肝脏砷形态分析

Distribution of arsenic metabloite in liver of rats treated with arsenite and arsenate

目的通过观察不同价态无机砷染毒大鼠肝脏砷形态代谢产物分布,初步探讨不同价态无机砷体内代谢和毒性机制。方法 W istar大鼠42只,随机分成7组,于染砷3个月后,处死动物,迅速摘取肝脏,于-80℃冷藏;采用高效液相色谱-氢化物发生原子荧光光谱法(HPLC-HGAFS)测定并比较各组染砷大鼠肝脏中砷形态代谢产物的水平和分布,计算一甲砷酸(MMA)加标回收率评价结果准确度;通过肝脏中总砷含量评价砷蓄积能力;分析肝脏中甲基化代谢指标一甲基化率(PM I)和二甲基化率(SM I)水平,评价各组间甲基化代谢能力或途径差异。结果亚砷酸钠与砷酸钠高、中、低剂量组总砷水平分别为(1 142.9±50.4)、(484.6±37.4)、(323.3±20.2)和(3 695.2±345.9)、(1833.8±229.6)、(1 170.5±77.4)ng/g,砷酸钠各剂量组总砷水平明显高于亚砷酸钠组(P<0.05);亚砷酸钠中、低剂量组iAs3+[(118.4±23.9)、(252.3±14.3)]ng/g和二甲砷酸(DMA)[(353.2±45.6)、(55.2±10.6)]ng/g含量均低于砷酸钠组(P<0.05);亚砷酸钠中、低剂量组MMA含量高于砷酸钠组(P<0.05),同时,亚砷酸钠各剂量组PMI和SMI均低于砷酸钠各剂量组(P<0.05)。结论五价砷代谢产物在肝脏蓄积能力强于三价砷,五价砷在肝脏一甲基化及二甲基化代谢能力强于三价砷,具有较大肝脏毒性。

Objective To analyze the difference in distribution of arsenic metabolite in liver of the rats treated with arsenite and arsenate,and to explore metabolism and toxicity of arsenic.Methods Seventy-two Wistar rats were devided into 7 groups.After three months＇ treatment,the liver samples of the rats were collected and kept in deep freeze refrigerator.With high efficiency liquid chromatography and hydride genesis atomic fluorescence spectroscopy（HPLC-HGAFS）,the speciation and concentrations of arsenate and arsenite and their metabolic products in the liver were determined.Meanwhile,the recovery rate of monomethylarsonic acid（MMA） was determined to estimate the accuracy of the results.The arsenic accumulation was evaluated based on the content of total arsenic in liver and the differences in pathway and capability of methylation were estimated according to levels of primary methylated index（PMI） and secondary methylated index（SMI） of arsenic in the liver.Results There were significant differences in the levels of total arsenic between high,moderate,and low arsenite groups（1 142.9±50.4,484.6± 37.4,323.3±20.2 ng/g wet weight） and between high,moderate,and low arsenate groups（3 695.2±345.9,1 833.8±229.6,1 170.5± 77.4 ng/g wet weight）（P0.05 for all）.Except high dose group,the level of iAs3＋（118.4±23.9,252.3±14.3 ng/g wet weight） and dimethylarsinic acid（DMA）（353.2±45.6,55.2±10.6 ng/g wet weight） in the liver of moderate and low arsenite group were lower than the level of iAs3＋（558.7±39.0,759.5±67.6 ng/g wet weight）and DMA（1269.7±219.9,402.1±60.5 ng/g wet weight）in moderate and low arsenate groups（P0.05）.The level of MMA（13.0±2.88,15.8±3.14 ng/g wet weight）in the liver of moderate and low arsenite group were higher than the level of MMA（5.35±1.18,8.87±1.66 ng/g wet weight）of the moderate and low arsenate groups（P0.05）.The level of PMI and SMI of different arsenite group in the liver were lower than the same dose arsenate groups（P0.05）.Conclusion The accumulation of pentavalent arsenic metabolite is more than that of trivalent arsenic in the liver of rats.In the liver the primary and secondary methylation of pentavalent arsenic is more intensive than that of trivalent arsenic and with stronger hepatic toxicity in rats.