Hepatic and splenic microsomal electron transport system function, microsomal heme oxygenase activity, and microsomal drug metabolism have been examined in male Wistar rats bearing Murphy-Sturm lymphosarcoma 2 to 15 days following i.m. tumor transplantation. Hepatic microsomal cytochrome P450 and NADPH-cytochrome c reducÃ-ase activity decreased significantly [cytochrome P-450 nadir was 0.49 ± ...

Trout liver microsomes contained as 0.40 nmole of cytochrome P-450 per mg of protein and a NADPH-cytochrome c reductase activity of 23 nmoles of cytochrome c reduced per mg of protein per min at 22 degrees. Associated with these was a high benzo(a)pyrene hydroxylase activity, which required NADPH and O2 and was inhibited by CO. With thin-layer chromatography, at least five metabolites could be ...

An improved high-performance liquid chromatography/fluorometric assay has been established to quantitate the benzo(a)pyrene (BP) tetrols released after acid hydrolysis of lung DNA from lung cancer patients, so that the formation of benzo(a)pyrene diol-epoxide-DNA adducts can be measured. The r-7,c-10,t-8,t-9-tetrahydroxy-7,8,9,10-tetrahydro-BP isolated by high-performance liquid chromatography ...

Numerous reports have illustrated the versatility of polychlorinated biphenyls (PCBs) and related halogenated aromatics as inducers of drug-metabolizing enzymes and the activity of individual compounds are remarkably dependent on structure. The most active PCB congeners, 3,4,4',5-tetra-, 3,3',4,4'-tetra-, 3,3',4,4',5-penta- and 3,3',4,4',5,5'-hexachlorobiphenyl, are substituted at both para and...

The rote of prostaglandin endoperoxide synthetase in thà ̈ in vìvo activation of benzo(a)py rene to reactive metabolites capable of interacting irreversibly with cellular macromolecules was stud ied in guinea pig liver, lung, kidney, spleen, small intestine, colon, and brain. DNA and protein covalent binding experiments were made after systemic administration of acetylsalicylic acid (200 mg/kg)...

The human P-450 CYP1A1 gene and a P450IA2 complementary DNA have been expressed in Cos-1 cells and the expressed proteins were assayed for their capacity to metabolize the carcinogens 2-acetylaminofluorene (AAF), benzo(a)pyrene, 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, 2-amino-3,4,8-trimethylimidazo...

Chemically induced rat liver nodules and cancers characteristically demonstrate a limited capacity to activate xenobiotics to reactive species mainly because of decreased amounts of cytochrome P-450. These lesions also show enhancement of xenobiotic detoxication by such mechanisms as enzymic conjugation or reduction of cytotoxic species. We recently demonstrated a similar pattern of metabolic a...

A rapid and inexpensive method has been developed to estimate rates of benzo(a)pyrene phenol production by per fused rat liver. This method is based on the measurement of benzo(a)pyrene phenols utilizing a simple fluorometric proce dure. Within 2 to 3 min after infusion of benzo(a)pyrene bound to serum albumin, phenols are excreted into the perfusate, primarily as glucuronide and sulfate conjug...

Hepatic and splenic microsomal electron transport system function, microsomal heme oxygenase activity, and microsomal drug metabolism have been examined in male Wistar rats bearing Murphy-Sturm lymphosarcoma 2 to 15 days following i.m. tumor transplantation. Hepatic microsomal cytochrome P450 and NADPH-cytochrome c reducÃ-ase activity decreased significantly [cytochrome P-450 nadir was 0.49 ± ...

The similarity in enzyme profile between microsomal preparations and nuclear envelopes has been shown for a range of enzymes in adult liver of various species (Franke, 1974; Kasper, 1974). The degree to which the enzymes in these two membrane systems can be induced is, however, variable. In rat liver, phenobarbital produced a two to three times increase in NADPH-cytochrome c reductase (EC 1.6.2...