Umbenhauer D R, Pegg A E
Chem Biol Interact. 1981 Jan;33(2-3):229-38. doi: 10.1016/0009-2797(81)90043-0.
Freshly prepared isolated hepatocytes were shown to metabolize dimethylnitrosamine producing an alkylating agent which reacted with cellular DNA giving rise to 7-methylguanine and O6-methylguanine. Alkylation of DNA was prevented by aminoacetonitrile and was proportional to the dimethylnitrosamine concentration over the range of 1--90 microM. Isolated hepatocytes were able to catalyze the removal of O6-methylguanine from their DNA. After formation of this product by reaction with N-methyl-N-nitrosourea or dimethylnitrosamine to give extents of alkylation in the range of 0.1--15.0 mumol O6-methylguanine per mole of guanine in DNA, the loss produced in 3 h incubation was comparable to that seen in vivo from liver DNA alkylated to the same extent. The isolated hepatocytes therefore, provide a useful system in which factors influencing O6-methylguanine persistence in DNA can be studied.
新鲜制备的分离肝细胞被证明能够代谢二甲基亚硝胺，产生一种烷基化剂，该烷基化剂与细胞DNA反应，生成7-甲基鸟嘌呤和O6-甲基鸟嘌呤。氨基乙腈可阻止DNA的烷基化，且在1-90微摩尔的浓度范围内，DNA的烷基化与二甲基亚硝胺浓度成正比。分离的肝细胞能够催化从其DNA中去除O6-甲基鸟嘌呤。在用N-甲基-N-亚硝基脲或二甲基亚硝胺反应形成该产物后，DNA中每摩尔鸟嘌呤的烷基化程度在0.1-15.0微摩尔O6-甲基鸟嘌呤范围内，在3小时孵育中产生的损失与在体内相同程度烷基化的肝脏DNA中观察到的损失相当。因此，分离的肝细胞提供了一个有用的系统，可用于研究影响DNA中O6-甲基鸟嘌呤持久性的因素。
