中文摘要：

目的探讨叔丁基对苯二酚（tert-butylhydroquinone, tBHQ）对Chang肝细胞无机砷甲基化代谢的影响。方法将Chang肝细胞密度调整为1×10^5个ml，采用25μmol／LtBHQ溶液预处理24h后，再用5μmol／L的tBHQ溶液和0．1、0．5、1．0和5．0μmol／L亚砷酸钠溶液联合染毒24h；并采用0．1、0．5、1．0和5．0μmol／L亚砷酸钠溶液单独染毒24h；并设溶剂对照（三蒸水）。采用超低温捕集-氢化物发生-原子吸收分光光度法分别测定细胞内和培养液中的无机砷（inorganic arsenic，iAs）、一甲基砷（monomethylated arsenic，MMA）和二甲基砷（dimethylated arsenic，DMA）含量，并计算一甲基化率（primary methylation index，PMI）和二甲基化率（secondary methylation index，SMI）。结果随着亚砷酸钠染毒剂量的增加，亚砷酸钠单独染毒组和tBHQ＋亚砷酸钠染毒组Chang肝细胞内tAs和iAs含量及Chang肝细胞和培养液中的总MMA含量均升高；亚砷酸钠单独染毒组细胞＋培养液总DMA含量之间无差异；tBHQ＋亚砷酸钠染毒组细胞＋培养液总DMA含量呈上升趋势；0．5μmol／L亚砷酸钠单独染毒组和tBHQ＋亚砷酸钠染毒组细胞＋培养液中的PMI最高，然后随着亚砷酸钠染毒浓度的升高而逐渐降低；亚砷酸钠单独染毒组细胞＋培养液中的SMI呈逐渐降低，而tBHQ＋亚砷酸钠染毒组细胞＋培养液中的SMI呈逐渐升高趋势。此外，与相同浓度的亚砷酸钠单独染毒组比较，tBHQ＋0．5，1．0、5．0μmol／L亚砷酸钠染毒组Chang肝细胞内的tAs和iAs含量较低僻〈0．05），而细胞＋培养液中总DMA含量、PMI和SMI则较高（P〈0．05）。结论高浓度砷暴露能够抑制砷的二甲基化过程；而tBHQ预处理能够增加砷的甲基化代谢，降低肝细胞内砷含量，从而增强Chang肝细胞对无机砷暴露的解毒能力。

英文摘要：

Objective To study the effects of tert-butylhydroquinone （tBHQ） on methylation metabolism of inorganic arsenic in Chang hepatocytes. Methods Chang hepatocytes were adjusted to 1×10^5 个/ml,and then pre-treated with tBHQ （25 μmol/L） for 24 h. Cells were next co-treated with tBHQ （5μmol/L） and sodium arsenite （0.1,0.5,1.0 and 5.0 μmol/L） for another 24 h ,or treated with sodium arsenite （0.1,0.5,1.0 and 5.0 μmol/L） alone for 24 h. Solvent control was established with triply distilled water. The levels of inorganic ansenic （iAs）,monomethylated arsenic （MMA） and dimethylated arsenic （DMA） in cells and medium were determined by cold trap hydride generation atomic absorption spectrophotometer respectively,and primary methylation index （PMI） and secondary methylation index （SMI） were calculated accordingly. Results iAs,MMA and DMA were all detected in hepatocytes as well as in culture medium. The concentration of hepatocellular tAs and iAs,as well as total MMA levels in hepatocytes plus culture medium were all elevated with increased doses of inorganic exposure （P〈0.05）, both in tBHQ co-treatment groups,as well as in sodium arsenite single groups; The total DMA levels were elevated with increased doses of inorganic exposure in tBHQ co-treatment groups （P〈0.05）,while remained unchanged in sodium arsenite alone groups; The PMI values were the highest in 0.5μmol/L of arsenic with tBHQ co-treatment group,as well as in sodium arsenite alone group, and thereafter decreased in high levels of arsenic exposure （P〈0.05）; The SMI values were reduced with the increased arsenic exposure （P〈0.05）,while enhanced in tBHQ co-treatment groups （P〈0.05）. The hapatocellular tAs and iAs levels decreased,while total DMA,PMI and SMI values increased significantly （P〈0.05） in 0.5,1.0 and 5.0 μ mol/L doses of sodium arsenite exposure co-treated with tBHQ,compared with the same concentration of sodium arsenite alone groups. Conclusion High concentration of inorgan