The Nature of Hepatic Cytochrome P-450 Induced in Hexachlorobenzene-Fed Rats

1978 ◽  
Vol 55 (5) ◽  
pp. 461-469
Author(s):  
G. H. Blekkenhorst ◽  
L. Eales ◽  
N. R. Pimstone
Keyword(s):  
Catalytic Properties ◽  
Enzyme System ◽  
Spectral Studies ◽  
Time Intervals ◽  
Female Wistar Rats ◽  
Kinetics Of ◽  
Cytochrome P 450 ◽  
Effect Of Feeding ◽  
Hepatic Cytochrome

1. The effect of feeding with a diet containing 0.2% (w/w) hexachlorobenzene on hepatic and urinary porphyrins and hepatic cytochrome P-450 was studied at various time intervals in female Wistar rats. 2. Hexachlorobenzene administration for 45 days resulted in the development of porphyria in rats, which biochemically closely resembles symptomatic porphyria in humans, with elevation of urinary uroporphyrin excretion, hepatic uroporphyrin content, and hepatic cytochrome P-450 content, in addition to appearance of porphyrins of the isocoproporphyrin (P1) series in the faeces. 3. Spectral studies of the induced hepatic cytochrome P-450 at 45 days with carbon monoxide and ethyl isocyanide as ligands indicated the presence of a greater admixture of a haemoprotein distinct from cytochrome P-450. 4. Study in vitro of the kinetics of two reactions, namely aminopyrine N-demethylation and 3,4-benzpyrene hydroxylation, catalysed by the hepatic microsomal cytochrome P-450-dependent enzyme system, suggested that hexachlorobenzene induced a form of cytochrome P-450 with different catalytic properties from those of forms induced by either phenobarbital or 3-methylcholanthrene.

Kinetics of hepatic cytochrome P-450 reduction: correlation with spin state of the ferric heme

Biochemistry ◽  
1982 ◽  
Vol 21 (6) ◽  
pp. 1324-1330 ◽  
Author(s):  
Wayne L. Backes ◽  
Stephen G. Sligar ◽  
John B. Schenkman
Keyword(s):  
Spin State ◽  
Ferric Heme ◽  
Kinetics Of ◽  
Cytochrome P 450 ◽  
Hepatic Cytochrome

scholarly journals Decreased liver cytochrome P-450 in rats caused by norethindrone or ethynyloestradiol

1977 ◽  
Vol 166 (1) ◽  
pp. 57-64 ◽  
Author(s):  
I N H White ◽  
U Muller-Eberhard
Keyword(s):  
Marked Effect ◽  
Enzyme System ◽  
Time Dependent ◽  
Female Rats ◽  
Liver Cytochrome ◽  
Mixed Function Oxidases ◽  
Green Pigments ◽  
Cytochrome P 450

1. 19-Nor-17alpha-pregna-1,3,5(10)-trien-20-yne-3,17-diol (ethynyloestradiol) or 17beta-hydroxy-19-nor-17alpha-pregn-4-en-20-yn-3-one (norethindrone) but not 17alpha-ethyl-17beta-hydroxy-19-norandrost-4-en-3-one (norethandrolone) caused a time-dependent loss of cytochrome P-450 when incubated in vitro with rat liver microsomal fractions and NADPH-generating systems. 2. The enzyme system catalysing the norethindrone-mediated loss of cytochrome P-450 had many characteristics of the microsomal mixed-function oxidases. It required NADPH and air, and was inhibited by Co. However, it was unaffected by 1 mM-compound SKF 525A. 3. In microsomal fractions from phenobarbitone-pretreated rats the norethindrone-mediated loss of cytochrome P-450 was increased relative to controls. The norethindrone-mediated cytochrome P-450 loss was less pronounced when the animals were pretreated with 3beta-hydroxy-pregn-5-en-2-one 16alpha-carbonitrile (pregnenolone 16alpha-carbonitrile). Pretreatment with 3-methylcholanthrene rendered the animals resistant to the norethindrone effect. 4. Administration in vivo [100mg/kg, intraperitoneally] of norethindrone or ethinyl oestradiol also produced a time-dependent loss of liver cytochrome P-450. Norethandrolone had a similar, though much less-marked, effect. All three steroids lead to an induction of 5-aminolaevulinate synthase and an accumulation of porphyrins in the liver. 5. The loss of cytochrome P-450 and the accumulation of porphyrins in the liver 2 h after the administration of norethindrone to female rats was similar to that seen in males. 6. Rats pretreated with phenobarbitone and given norethindrone or ethynyloestradiol (100mg/kg, intraperitoneally) formed green pigments in their livers. These had characteristics similar to the green pigments produced in the livers of rats after the administration of 2-allyl-2-isopropylacetamide. No green pigments could be extracted from the livers of control rats or those given norethandrolone, oestradiol or progesterone.

scholarly journals Biosynthesis of phosphatidylethanolamines and phosphatidylcholines from ethanolamine and choline in rat liver

1975 ◽  
Vol 146 (2) ◽  
pp. 309-315 ◽  
Author(s):  
R Sundler ◽  
B Akesson
Keyword(s):  
Rat Liver ◽  
Molecular Species ◽  
Kinetic Models ◽  
Quantitative Data ◽  
Specific Radioactivity ◽  
Similar Rate ◽  
Time Intervals ◽  
Previous Suggestion ◽  
Kinetics Of

1. The kinetics of phosphatidylcholine and phosphatidylethanolamine synthesis in rat liver were followed 5-60 min after the intraportal injection of [14-C]choline and [3-H]-ethanolamine. 2. At all time-intervals the specific radioactivity of CDP-choline was only about half that of phosphorylcholine. This indicated that CDP-choline was formed at a similar rate from phosphorylcholine and phosphatidylcholines, the latter probably through the reverse reaction of cholinephosphotransferase (EC 2.7.8.2.). In view of recent data obtained from experiments in vitro this implies a significant role for the cholinephosphotransferase reaction in the turnover of molecular species of phosphatidylcholine. 3. The specific radioactivity of CDP-ethanolamine was about twice that of phosphorylethanolamine at all time-intervals studied. This supports a previous suggestion that the liver phosphorylethanolamine pool is subject to compartmentation and shows that there is no rapid equilibration between different pools. In contrast with a recent study, no evidence was found for any significant methylation of phosphoryl-or CDP-ethanolamine to the corresponding choline derivative. 4. Quantitative data on the biosynthesis of molecular species of phosphoLIPIDS via CDP derivatives were calculated according to simple kinetic models. They were in the same range as those calculated from earlier data on precusors incorporated via diacylglycerols. 5. The proportion of radioactive phosphatidylethanolamines appearing in the plasma was approximately ten times lower than that for phosphatidylcholines. No selectivity was observed in the transfer into plasma of different molecular species of phosphatidylethanolamine.

Effect of feeding quandong (santalum acuminatum) oil to rats on tissue lipids, hepatic cytochrome P-450 and tissue histology

1994 ◽  
Vol 32 (6) ◽  
pp. 521-525 ◽  
Author(s):  
G.P. Jones ◽  
A. Birkett ◽  
A. Sanigorski ◽  
A.J. Sinclair ◽  
P.T. Hooper ◽  
...  
Keyword(s):  
Tissue Lipids ◽  
Tissue Histology ◽  
Cytochrome P 450 ◽  
Effect Of Feeding ◽  
Hepatic Cytochrome

Effect of Feeding and of DDT on the Activity of Hepatic Glucose 6-Phosphate Dehydrogenase in Two Salmonids

1969 ◽  
Vol 26 (12) ◽  
pp. 3209-3216 ◽  
Author(s):  
Donald R. Buhler ◽  
P. Benville
Keyword(s):  
Rainbow Trout ◽  
Coho Salmon ◽  
Specific Activity ◽  
Enzyme System ◽  
Regulatory Control ◽  
Hepatic Glucose ◽  
Dehydrogenase Enzyme ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Effect Of Feeding

The specific activity of liver glucose 6-phosphate dehydrogenase in yearling rainbow trout remained unchanged when the fish were starved for periods as long as 8 weeks and when starved animals were fed diets of various compositions. Injection of insulin concurrently with refeeding also failed to alter the specific activity of the enzyme in trout. The absence of a dietary or insulin influence on the teleost enzyme system is to be contrasted with studies in mammals in which the activity of hepatic glucose 6-P dehydrogenase was markedly stimulated after refeeding starved animals or injection of insulin.Ingestion of the pesticide DDT by juvenile coho salmon or adult rainbow trout also had no effect on the specific activity of liver glucose 6-P dehydrogenase and DDT failed to inhibit the rainbow trout enzyme in vitro. These results also differ considerably from those found in higher animals.These results suggest that the glucose 6-P dehydrogenase enzyme in teleosts may be under a different type of regulatory control from that found in mammals.

Direct in vitro effects of bis (tri-n-butyltin)oxide on hepatic cytochrome P-450

1983 ◽  
Vol 32 (24) ◽  
pp. 3823-3829 ◽  
Author(s):  
Daniel W. Rosenberg ◽  
George S. Drummond
Keyword(s):  
In Vitro Effects ◽  
Cytochrome P 450 ◽  
Hepatic Cytochrome
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