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A requirement for dietary lipids for induction of cytochrome P-450 by phenobarbitone in rat liver microsomal fraction.

ABSTRACT: 1. Rats fed on purified synthetic diets have a markedly lower cytochrome P-450 concentration and hydroxylating enzyme activity in liver microsomal fraction than rats fed on stock pellets. 2. When both groups are treated with phenobarbitone the difference is even greater, the purified diet allowing only 50% of the cytochrome P-450 concentrations of controls. 3. Addition of herring oil, linoleic acid or 0.1% oxidized sitosterol to the diets allows induction of cytochrome P-450 to take place. 4. Addition of coconut oil to the diet does not permit induction of cytochrome P-450. 5. The interactions between dietary protein and the lipid substances are explored. 6. The mechanism of induction of microsomal hydroxylation enzymes by drugs is discussed in the light of these requirements.

SUBMITTER: Marshall WJ

PROVIDER: S-EPMC1176815 | biostudies-other | 1971 May

REPOSITORIES: biostudies-other

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Phospholipid requirement for 2-acetamidofluorene N-and ring-hydroxylation by hamster liver microsomal cytochrome P-450 enzyme system.

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| S-EPMC1177245 | biostudies-other

Role of haem in the induction of cytochrome P-450 by phenobarbitone. Studies in chick embryos in ovo and in cultured chick embryo hepatocytes.

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Cloning of cytochrome P-450 2C9 cDNA from human liver and its expression in CHL cells.

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Cytochrome P-450 and hydroxylating activity of microsomal preparations from whole houseflies.

Project description:1. A new microsomal preparation, obtained from whole houseflies is described in terms of its cytochrome P-450 content and its hydroxylating activity. 2. Microsomes prepared from whole-fly brei, obtained with the aid of a mortar (a procedure that avoids the destruction of sarcosomes), contain 0.265nmol of cytochrome P-450 and hydroxylate naphthalene at a rate of 28.5nmol/mg of microsomal protein in 30min at 30 degrees C. This corresponds to 104nmol of naphthalene hydroxylated/nmol of cytochrome P-450. This is the highest rate ever reported for housefly and rat liver microsomal preparations. 3. Microsomal fractions prepared by procedures that do not retain the integrity of sarcosomes show the presence in the CO-difference spectrum of a 428nm peak. This cytochrome is associated with sarcosomal microsomes and it may be involved in the inhibition of insect microsomal mixed-function oxidases, although other factors cannot be discarded at present. 4. The inability to show cytochrome P-450 in microsomal fractions isolated from whole houseflies by other procedures may be at least partially due to a masking effect brought about by contamination with the sarcosomal cytochrome.

| S-EPMC1177128 | biostudies-other

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