中文摘要：

目的分析肝脏中甲基转移酶活力与砷代谢产物相关性,探讨不同价态砷体内代谢与其毒性关系。方法雌性Wistar大鼠42只分成7组,对照组,亚砷酸钠高、中、低剂量组;砷酸钠高、中、低剂量组;连续染毒3个月,处死动物,摘取肝脏,于-80℃冷藏保存;采用高效液相色谱-氢化物发生原子荧光光谱法测定并比较不同价态染砷大鼠肝脏中砷形态水平,检测肝脏中甲基转移酶活力,探讨两者相关性。结果亚砷酸钠高、中、低剂量组iAs3＋含量分别为（255.9±58.6）、（61.1±10.2）、（62.6±17.3）ng/g,均低于砷酸钠各剂量组（P〈0.05）;亚砷酸钠高、中、低剂量组二甲砷酸（DMA）含量分别为（2 663.2±203.7）、（118.4±24.2）、（143.5±34.1）ng/g,均低于砷酸钠组（P〈0.05）;亚砷酸钠高、中、低剂量组甲基转移酶活力分别为（4.81±0.25）、（2.32±0.41）和（1.82±0.25）μg/（s.mg）,均低于砷酸钠高、中、低同一剂量组（P〈0.05）;相关分析显示,肝脏中甲基转移酶活力与DMA和一甲砷酸（MMA）的含量均呈正相关（P〈0.01）,相关系数分别为0.594和0.497。结论不同价态砷均可通过促进（或抑制）肝脏甲基转移酶活力,诱导肝脏DMA、MMA水平升高（或降低）,发挥不同毒性作用。

英文摘要：

Objective To analyze the association between the level of arsenite or arsenate and its metabolites and the activity of methyltransferases, and to explore the relationship between arsenic＇ s metabolism and toxicity. Methods Forty-two female Wistar rats were devided into 7 groups （normal control group;high, moderate, and low arsenite groups and nigh, moderate, and low arsenate groups）. After the animals were treated for three months, the liver were collected rap- idly after the sacrifice and saved in a refrigerator. High efficiency liquid chromatography and hydride genesis atomic fluo- rescence spectroscopy （HPLC-HGAFS） were used to determine speciation and concentrations of arsenate and arsenite and their metabolites in liver of the rats, and the activity of methyltransferases in the liver was determined. Meanwhile the cor- relation between the level of arsenic metabolites and the activity of methyltransferases was examined. Results The con- tents of iAs3＋ for the rats in high,moderate,and low arsenite groups（255.9 ±58.6,61.1 ± 10. 2,and 62. 6 ±17. 3 ng/g） were significantly lower than those in arsenate groups（P 〈 0. 05 for all）. The contents of dimethylarsinic acid（DMA） in the rats of nigh,modrate,and low arsenite groups（2 663.2±203.7,118.4 ±24. 2,and 143.5 ±34. 1 ng/g） were signifi- cantly lower than those in arsenate groups （ P 〈 0.05 for all）. Meanwhile, the activity of methyltransferases in high, mod- erate,and low arsenite groups（4. 81 ±0. 25,2. 32±0. 41 ,and 1.82±0. 25 μg/s.mg） were significantly lower than those in arsenate groups （P 〈 0. 05 for all）. The activity of methyltransferase in liver correlated positively with the content of DMA and monomethylarsonic acid（MMA） by Spearman methods（ P 〈 0. 01 ）, with the correlation coefficients of 0. 594 and 0. 497 ,respectively. Conclusion Both arsenate sodium and arsenite sodium could increase（ or decrease） the level of MMA and DMA by enhancing （or restraining） the activity of methyltransf