Induction of the Drug Metabolizing System in Rainbow Trout (Salmo gairdnerii) Liver by Polychlorinated Biphenyls (PCBs)

Abstract Clophen A50 is shown to enhance the O–demethylation of p–nitroanisole to p–nitrophenol and to elevate the cytochrome P–450–content of the rainbow trout liver. Three days after feeding, the O–demethylating activity had increased about 4–fold while the cytochrome P–450–concentration was unchanged. This suggests that the process is divided into two or more steps, with an initial lag in the cytochrome P–450 formation. From 7 days and throughout the experiment a concomitant increase in the O–demethylating activity and the cytochrome P–450–content can be observed. The increased activity can not, however, be solely correlated to the increase in cytochrome P–450 content.     

二硫化碳对妊娠母鼠及胎鼠肝混合功能氧化酶活性影响的研究

研究表明,未经苯巴比妥钠处理的妊娠母鼠,腹腔注射染毒组胎肝细胞色素P-450、细胞色素b_5和蛋白质含量均明显低于对照组。125和11mg/m~3吸入染毒组胎肝细胞色素P-450和蛋白质含量也明显低于对照组。但细胞色素b_5仅125mg/m~3染毒组低于对照组。腹腔注射CS_2染毒时,妊娠母鼠和胎鼠肝NADPH-细胞色素C-还原酶均显著高于对照组。     

Nitrite binding to cytochrome P-450 from liver microsomes of trout (Salmo gairdneri Rich.) and effects on two microsomal enzymes

Addition of nitrite to dithionite-reduced trout liver microsomes leads to the conversion of cytochrome P-450 into a cytochrome P-420-NO complex, as it does in mammalian microsomes. A loss in cytochrome P-450 and an inhibition of aminopyrine demethylase (AP) activity were observed in vitro at nitrite-concentrations found in the liver of trout exposed in vivo to this toxin. Nitrite had no effect on dimethylaniline monooxygenase (DMA), a cytochrome P-450-independent enzyme.     

Effects of disulfiram on mixed function oxidase system and trace element concentration in the liver of rats

Disulfiram (DSF), an inhibitor of chemically induced carcinogenesis, and its metabolite diethyldithiocarbamate (DDTC) have been investigated for their influence on trace element distribution and on certain enzymes of the drug metabolizing system in the livers of phenobarbital (PB) treated rats. Both substances diminished the PB induced enzyme response in liver microsomes, DDTC being more effective (?85%) than DSF (?60%). The copper, cobalt and zinc content of the livers of DSF treated animals were increased by factors of 6, 3 and 1.5 respectively as compared to controls, while DDTC treatment had no influence on liver trace element content. A correlation between enzyme inhibition and enhanced trace element uptake of the liver after DSF administration could not be observed. The change of trace element transport into the liver during DSF treatment is discussed.