Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hexachlorobenzene, which is a widespread contaminant of meat and meat animal by-products throughout the world, had a profound effect on the homeostatic mechanism which controls the serum testosterone concentrations in the mouse. Significant increases in the mean hepatic weight, the concentrations of hepatic microsomal protein, cytochrome P-450, cytochrome b5, and cytochrome c reductase activity occurred in the aminals given a ration containing 250 mg of hexachlorobenzene/kg for 21 days, when compared with their nontreated controls. These increases in cytochrome concentrations and enzyme activity of the hepatic microsomes are reflected by significant increases in the in vitro metabolism of [3H]testosterone and a decrease in the serum concentrations of testosterone with a concomitant decrease in the weights of the seminal vesicles and ventral prostate of the mouse.
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PMID:Testosterone metabolism by hexachlorobenzene-induced hepatic microsomal enzymes. 52 97

The effect of chronic ethanol consumption on the ability of isolated liver fractions to metabolize the carcinogen N-nitrosopyrrolidine (NPY) was examined. Microsomal fractions of treated animals exhibited increased rates of alpha-hydroxylation of NPY. Similar increases in the specific activities of aniline hydroxylase, reduced nicotinamide adenine dinucleotide phosphate cytochrome c reductase, and the specific content of cytochrome P-450 were also observed. In contrast, no differences in the specific activities of benzo(a)pyrene hydroxylase or glucose-6-phosphatase were observed. Liver postmitochondrial supernatants from ethanol-consuming animals were able to produce 5 times more mutants than did control preparations. It is concluded that alpha-hydroxylation of NPY is probably the mechanism by which NPY is converted to a mutagen and that this pathway can be induced by ethanol.
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PMID:Enhanced metabolism and mutagenesis of nitrosopyrrolidine in liver fractions isolated from chronic ethanol-consuming hamsters. 57 Aug 82

The effects of clofibrate on the fine structure and drug-metabolizing capacity of livers of normolipidemic young adult virgin (YA) and hypercholesterolemic retired breeder (RB) male rats were measured by morphometric and biochemical procedures. The oral administration of clofibrate for 7 days significantly increased liver weight and reduced the cholesterol concentrations in the serum and liver tissue in both groups of animals. The hepatic triglyceride (TG) concentration and the volume of cytoplasmic lipid droplets, presumably TG, as well as the serum TG concentration, increased only in the drug-treated RB rats. Clofibrate treatment resulted in significant increases in the volumes of the hepatocytes and their constituent mitochondria and microbodies and caused a proliferation of the smooth-surfaced endoplasmic reticulum. Although the magnitude of the hypocholesterolemic response was considerably greater in the RB animals, the morphological changes were much more marked in the YA group. However, the surface area of the rough-surfaced endoplasmic reticulum was reduced in the livers of the drug-treated RB rats. NADPH cytochrome c reductase specific activity was significantly increased in both the RB and YA animals, but the concentration of cytochrome P-450 (per mg microsomal protein) increased only in the YA rats. Neither the cytochrome b5 concentration nor the rate of ethylmorphine N-demethylation was significantly affected by clofibrate administration. The results suggest that there is no positive correlation between the hypocholesterolemic response to clofibrate and the degree of subcellular changes in the hepatocytes and that this hypolipidemic drug elicits a minimal effect on the concentrations of the components of the hepatic microsomal drug-metabolizing system.
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PMID:A quantitative analysis of fine structure and drug metabolism in livers of clofibrate-treated young adult and retired breeder rats. 63 78

Prolongation effects of promethazine on the pentobarbital sleeping time are not due to interactions of this drug with cytochrome P-450 or cytochrome c reductase or inhibition of drug metabolism because pentobarbital plasma levels in promethazine treated animals before awakening are not different than in controls. Results suggest additive effects of both drugs on the central nervous system. Those interactions do however play a role during in vitro studies.
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PMID:In vitro and in vivo effects of promethazine (Phenergan) on drug metabolism. 64 27

A lauric acid monooxygenase which catalyzes the formation of hydroxylaurate from lauric acid has been characterized in ageing tissues of Jerusalem artichoke (Helianthus tuberosus L.) tuber. Three reaction products have been identified from the mass fragmentation pattern of their methyltrimethylsilyl derivatives: 10-hydroxylauric acid, 9-hydroxylauric acid and 8-hydroxylauric acid. Enzyme activity is located on the microsomal fraction which also carries cytochrome P-450 and NADPH cytochrome-c reductase. The apparent Km of the enzyme for lauric acid is 0.97 micronM. Laurate monooxygenation is dependent upon O2 and inhibited by CO. The latter effect is light reversible. NADPH is the preferred electron donor although appreciable NADH-sustained activity was observed. NADPH cytochrome c reductase is involved in electron transfer as evidenced by the inhibitory effects of NADP+ and oxidized cytochrome c on laurate monooxygenation. Thus, the enzyme catalyzing laurate oxidation in Jerusalem artichoke tuber tissues appears to be a typical (cytochrome P-450)-linked monooxygenase.
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PMID:A microsomal (cytochrome P-450)-linked lauric-acid-monooxygenase from aged Jerusalem-artichoke-tuber tissues. 71 Apr 15

Cadmium was administered into male rats in drinking water as cadmium chloride at a concentration equivalent to 250 ppm of cadmium for 2 and 8 weeks. The cadmium concentration in the liver microsomes was 0.85 +/- 0.11 microgram/g (wet wt) and in the supernatant 29.6 +/- 1.1 microgram/g and in the renal microsomes 1.30 +/- 0.30 microgram/g (w.wt) and in the supernatant 24.4 +/- 3.2 microgram/g after 8 weeks. In the intestinal postmitochondrial supernatant fraction the cadmium concentration was 14.2 +/- 1.0 microgram/g (wet wt) after 8 weeks administration. There was a slight increase in the hepatic cytochrome P-450 level, no changes in the hepatic p-nitroanisole O-demethylase and NADPH cytochrome c reductase activities and a clearcut induction in the hepatic aryl hydrocarbon hydroxylase activity after 8 weeks cadmium exposure. Renal activities followed mainly those of the liver. No changes were found in the hepatic UDPglucuronosyltransferase activity and a slight activation was present in the renal activity. The intestinal activities were markedly depressed after cadmium exposure. The results suggest that cadmium administration changes the drug biotransformation rates differently in various tissues.
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PMID:Cadmium-induced tissue specific changes in drug biotransformation rates in rats. 72 26

Administration of phenobarbital to rats over a period of 5 days was shown to increase hepatic lipid peroxidation concomitant with induction of cytochrome P-450 and cytochrome c reductase. The purpose of this study was to determine whether the increase in lipid peroxidation was due to a lowering in hepatic antioxidants. The results show that increased lipid peroxidation was not due to a decreased level of antioxidants since the fat-soluble antioxidants were unchanged and ascorbate, a water-soluble antioxidant, was elevated. The relationship of the increase in hepatic ascorbate to enhanced lipid peroxidation is discussed.
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PMID:Effects of phenobarbital administration on levels of physiological antioxidants in rat liver. 73 93

In the presence of hepatic microsomes, styrene produced a type I difference spectrum, which demonstrates that styrene binds to the catalytic site of ferricytochrome P-450. A comparison of the binding parameters for the interaction of styrene with noninduced, phenobarbital-induced, and 3-methylcholanthrene-induced microsomes indicated that styrene is predominantly bound by cytochrome P-450 and not by cytochrome P-448. Inhalation exposure to a mixture of acetone (1,000 ppm, 6 h/d) and styrene (300 ppm, 6 h/d) for 5 d caused a distinct decrease in hepatic free nonprotein sulfhydryl groups. This decrease could be observed both with and without phenobarbital treatment. Acetone inhalation alone also enhanced ethoxycoumarin O-deethylase activity in rats without pretreatments. Acetone inhalation also increased the cytochrome P-450 content of liver microsomes, but it had no effect on NADPH cytochrome c reductase or epoxide hydratase activity. Combined exposure to styrene and acetone enhanced NADPH cytochrome c reductase activity in nonphenobarbital-treated rats, but no effect was seen in the phenobarbital-treated animals. Phenobarbital treatment of animals can greatly modify the biotransformation and toxicity of styrene, phenobarbital inducible P-450 hemoprotein playing a predominant role in its metabolism. Simultaneous inhalation exposure to acetone also interacts with the metabolism of styrene.
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PMID:Interaction of styrene and acetone with drug biotransformation enzymes in rat liver. 73 16

In an attempt to understand dietary protein effects upon aflatoxin B1-induced liver cancer in rainbow trout, the activities of several suspected aflatoxin B1 metabolizing enzyme systems were studied relative to protein intake. Fish fed diets containing 32 percent, 52 percent and 62 percent fish protein concentrate (FPC) were examined for hepatic cytochrome P-450 content and in vitro cytochrome c reductase, glutathione-S-epoxide transferase (GTr), epoxide hydrase (EH) and aldrin epoxidase (AE) activity. In addition, aflatoxin B1 conversion to aflatoxicol (AFL) was examined. A direct correlation was observed between increased FPC intake and cytochrome P-450 content and AFL production, with increases of 14 percent and 41 percent respectively. With increased FPC intake, decreases in EH (15 percent), GRr (20 percent), cytochrome c reductase (13 percent) and AE (50 percent) activities were noted. These findings are discussed in relation to AFB feeding trials reported earlier.
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PMID:Dietary protein levels and aflatoxin B metabolism in rainbow trout (Salmo gairdneri). 73 17

The effect of glucagon on the components of the hepatic microsomal electron transport chain (NADPH oxidase, NADPH cytochrome c reductase (EC 1.6.2.4), cytochrome P-450, and NADPH cytochrome P-450 reductase), and on two representative oxidative pathways (aminopyrine N-demethylation, a type I substrate oxidation; and aniline p-hydroxylation, a type II substrate oxidation) was determined. Microsomes from rats pretreated with glucagon (300 mug/kg per day for 3 days) showed a significant decrease in NADPH oxidation and in aminopyrine N-demethylation with a prolonged hexobarbital sleeping time, and a significant increase in aniline p-hydroxylation. Microsomes from rats pretreated with a lower dose of glucagon (30 mug/kg per day for 3 days) showed a significant decrease in the microsomal N-demethylation of aminopyrine. Glucagon had no effect when added in vitro to microsomes, suggesting that the in vivo effects of glucagon are mediated indirectly in the intact animal.
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PMID:Alterations of hepatic microsomal drug metabolism by glucagon. 81 38


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