Biomaterial Database

Studies on the determination and induction of cholesterol 7alpha-hydroxylase. 1976

K Brandau, and U Keup

To determine the activity of cholesterol 7alpha-hydroxylase, different fractions from rat liver homogenates are incubated with glucose-6-phosphate, glucose-6-phosphate dehydrogenase and NADP as well as with cholesterol-4-14C. The 7alpha-hydroxycholesterol-4-14C formed is separated from the extract of the incubation preparation by means of thin-layer chromatography and its radioactivity is calculated as a percentage (conversion figure) of the total radioactivity on the plate. The highest conversion is found in the 18 000 X g supernatant. It is of the order of 1--4%. This activity decreases to about one-half when the homogenate or the cell fraction is stored, while cooling, for two days. It can be shown that repeated pretreatment of rats with phenobarbital increases the activity of hepatic cholesterol 7alpha-hydroxylase by more than three times over the control values. 1-(2'-Hydroxyphenyl-acetyl)-4-methyl-1,2,3,6-tetrahydropyridine (Bay a 4798) a choleretically active drug also increases the activity of this enzyme in the rat more than twofold. This effect is confirmed by reduced biliary excretion of radioactive cholesterol and increased biliary excretion of radioactive bile acids following i.v. administration of DL-mevalolactone-2-14C and continuous intraduodenal infusion of Bay a 4798.

UI	MeSH Term	Description	Entries
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D008297	Male		Males
D008862	Microsomes, Liver	Closed vesicles of fragmented endoplasmic reticulum created when liver cells or tissue are disrupted by homogenization. They may be smooth or rough.	Liver Microsomes,Liver Microsome,Microsome, Liver
D010634	Phenobarbital	A barbituric acid derivative that acts as a nonselective central nervous system depressant. It potentiates GAMMA-AMINOBUTYRIC ACID action on GABA-A RECEPTORS, and modulates chloride currents through receptor channels. It also inhibits glutamate induced depolarizations.	Phenemal,Phenobarbitone,Phenylbarbital,Gardenal,Hysteps,Luminal,Phenobarbital Sodium,Phenobarbital, Monosodium Salt,Phenylethylbarbituric Acid,Acid, Phenylethylbarbituric,Monosodium Salt Phenobarbital,Sodium, Phenobarbital
D010648	Phenylacetates	Derivatives of phenylacetic acid. Included under this heading are a variety of acid forms, salts, esters, and amides that contain the benzeneacetic acid structure. Note that this class of compounds should not be confused with derivatives of phenyl acetate, which contain the PHENOL ester of ACETIC ACID.	Benzeneacetates,Benzeneacetic Acids,Phenylacetic Acids,Acids, Benzeneacetic,Acids, Phenylacetic
D011725	Pyridines	Compounds with a six membered aromatic ring containing NITROGEN. The saturated version is PIPERIDINES.
D002756	Cholagogues and Choleretics	Gastrointestinal agents that stimulate the flow of bile into the duodenum (cholagogues) or stimulate the production of bile by the liver (choleretic).	Choleretics,Cholagogues,Cholagogues, Choleretics,Choleretics and Cholagogues,Hydrocholeretics
D002790	Cholesterol 7-alpha-Hydroxylase	A membrane-bound cytochrome P450 enzyme that catalyzes the 7-alpha-hydroxylation of CHOLESTEROL in the presence of molecular oxygen and NADPH-FERRIHEMOPROTEIN REDUCTASE. This enzyme, encoded by CYP7, converts cholesterol to 7-alpha-hydroxycholesterol which is the first and rate-limiting step in the synthesis of BILE ACIDS.	CYP7,CYP7A,Cytochrome P-450 CYP7,CYP 7,CYP 7A,Cholesterol 7-alpha-Monooxygenase,Cholesterol 7alpha-Hydroxylase,Cholesterol-7-Hydroxylase,Cytochrome P450 7,Cholesterol 7 Hydroxylase,Cholesterol 7 alpha Hydroxylase,Cholesterol 7 alpha Monooxygenase,Cholesterol 7alpha Hydroxylase,Cytochrome P 450 CYP7
D002855	Chromatography, Thin Layer	Chromatography on thin layers of adsorbents rather than in columns. The adsorbent can be alumina, silica gel, silicates, charcoals, or cellulose. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Chromatography, Thin-Layer,Thin Layer Chromatography,Chromatographies, Thin Layer,Chromatographies, Thin-Layer,Thin Layer Chromatographies,Thin-Layer Chromatographies,Thin-Layer Chromatography
D004790	Enzyme Induction	An increase in the rate of synthesis of an enzyme due to the presence of an inducer which acts to derepress the gene responsible for enzyme synthesis.	Induction, Enzyme