Pearson P G, Gescher A, Harpur E S, Threadgill M D
Biochem Pharmacol. 1987 Feb 1;36(3):385-90. doi: 10.1016/0006-2952(87)90299-1.
Incubation of the hepatotoxin N-methylformamide (NMF) labelled either in the methyl group (OHCNH14CH3) or the formyl group (OH14CNHCH3) with mouse hepatic microsomes in the presence of NADPH, but not in its absence, led to covalent binding of metabolites to microsomal proteins. When [14C]NMF was injected into BALB/c mice radioactivity was found to be associated with liver and, to a much lesser extent, with kidney proteins. Association of radioactivity derived from OHCNH14CH3 with hepatic proteins was higher in BALB/c mice than in CBA/CA mice and in these it was higher than in BDF1 mice. Association of label derived from either isotopomer was significantly reduced but not abolished by pretreatment of mice with cycloheximide suggesting both covalent binding and metabolic incorporation of NMF metabolites. Depletion of hepatic glutathione by pretreatment of mice with buthionine sulfoximine or diethyl maleate prior to administration of OH14CNHCH3 enhanced the association of label with hepatic proteins measured 1 hr after drug injection. Covalent binding of [14C]NMF to hepatic microsomes in vitro was abolished in the presence of glutathione. It is argued that the generation of the toxic lesion and the association of NMF metabolites with hepatic proteins may be causally related even though certain mechanistic and enzymatic details of this link remain obscure.
在有NADPH存在的情况下，而非不存在NADPH时，将标记于甲基（OHCNH14CH3）或甲酰基（OH14CNHCH3）的肝毒素N-甲基甲酰胺（NMF）与小鼠肝微粒体一起温育，会导致代谢产物与微粒体蛋白发生共价结合。当将[14C]NMF注射到BALB/c小鼠体内时，发现放射性与肝脏相关，与肾脏蛋白的相关性则小得多。源自OHCNH14CH3的放射性与BALB/c小鼠肝脏蛋白的结合高于CBA/CA小鼠，且在这些小鼠中高于BDF1小鼠。用环己酰亚胺预处理小鼠后，源自任何一种异构体的标记物的结合均显著降低但并未消除，这表明NMF代谢产物既有共价结合又有代谢掺入。在用丁硫氨酸亚砜胺或马来酸二乙酯预处理小鼠以耗尽肝脏谷胱甘肽后，再给予OH14CNHCH3，会增强给药1小时后测得的标记物与肝脏蛋白的结合。在有谷胱甘肽存在的情况下，[14C]NMF与肝微粒体在体外的共价结合被消除。有人认为，毒性损伤的产生以及NMF代谢产物与肝脏蛋白的结合可能存在因果关系，尽管这一联系的某些机制和酶学细节仍不清楚。
