scholarly journals Reversal of Sodium Arsenite Inhibition of Rat Liver Microsomal Ca2+ Pumping ATPase by Vitamin C

1999 ◽  
Vol 19 (1) ◽  
pp. 11-15 ◽  
Author(s):  
Odutayo O. Odunuga ◽  
Gbolahan W. Okunade ◽  
Olufunso O. Olorunsogo
Keyword(s):  
Vitamin C ◽  
Rat Liver ◽  
Sodium Arsenite ◽  
Microsomal Fraction ◽  
Specific Activity ◽  
Lethal Dose ◽  
Median Lethal Dose ◽  
Liver Microsomal Fraction

Sodium arsenite (NaAsO2), at 10% of its median lethal dose, was administered to rats with and without vitamin C pretreatment. Liver microsomal fraction was isolated and the activity of Ca2+-ATPase was assayed. Sodium arsenite was found to inhibit the activity of the liver microsomal Ca2+-ATPase to 50% to that of control rats. The specific activity of the enzyme in rats administered sodium arsenite with vitamin C pretreatment was not significantly different from that of control rats.

Influence of 1,4-benzdiazepin-2-ones on rat liver microsomal fraction and hepatocytes

1987 ◽  
Vol 21 (1) ◽  
pp. 5-8
Author(s):  
T. I. Davidenko ◽  
O. V. Sevast'yanov ◽  
L. N. Yakubovskaya
Keyword(s):  
Rat Liver ◽  
Microsomal Fraction ◽  
Liver Microsomal Fraction

scholarly journals Loss of haem in rat liver caused by the porphyrogenic agent 2-allyl-2-isopropylacetamide

1971 ◽  
Vol 124 (4) ◽  
pp. 767-777 ◽  
Author(s):  
F. De Matteis
Keyword(s):  
Rat Liver ◽  
Microsomal Fraction ◽  
Direct Evidence ◽  
Gradual Increase ◽  
Rapid Loss ◽  
Metabolizing Enzymes ◽  
Liver Microsomal Fraction ◽  
Green Pigments ◽  
Cytochrome P 450 ◽  
Increased Activity

1. The effect of a single dose of 2-allyl-2-isopropylacetamide on the cytochrome P-450 concentration in rat liver microsomal fraction was studied. The drug caused a rapid loss of cytochrome P-450 followed by a gradual increase to above the normal concentration. 2. The loss of cytochrome P-450 was accompanied by a loss of microsomal haem and by a brown–green discoloration of the microsomal fraction suggesting that a change in the chemical constitution of the lost haem had taken place. Direct evidence for this was obtained by prelabelling the liver haems with radioactive 5-aminolaevulate: the drug caused a loss of radioactivity from the haem with an increase of radioactivity in a fraction containing certain un-identified green pigments. 3. Evidence was obtained by a dual-isotopic procedure that rapidly turning-over haem(s) may be preferentially affected. 4. The loss of cytochrome P-450 as well as the loss of microsomal haem and the discoloration of the microsomal fraction were more intense in animals pretreated with phenobarbitone and were much less evident when compound SKF 525-A (2-diethylaminoethyl 3,3-diphenylpropylacetate) was given before 2-allyl-2-isopropylacetamide, suggesting that the activity of the drug-metabolizing enzymes may be involved in these effects. 5. The relevance of the destruction of liver haem to the increased activity of 5-aminolaevulate synthetase caused by 2-allyl-2-isopropylacetamide is discussed.

scholarly journals Binding of radioiodinated propylthiouracil to rat liver microsomal fractions. Stimulation by substrates for iodothyronine 5′-deiodinase

1979 ◽  
Vol 183 (1) ◽  
pp. 167-169 ◽  
Author(s):  
T J Visser ◽  
E Van Overmeeren
Keyword(s):  
Rat Liver ◽  
Enzyme Preparation ◽  
Microsomal Fraction ◽  
Sodium Sulphite ◽  
Enzyme Complex ◽  
Deiodinase Activity ◽  
Liver Microsomal Fraction ◽  
Thiouracil Derivatives

Previous studies have shown that 2-thiouracil derivatives are uncompetitive inhibitors of iodothyronine 5′-deiodinase activity of rat liver microsomal fraction. Therefore the interaction of radioiodinated 6-propyl-2-thiouracil with rat liver microsomal fraction and the effect of substrate, cofactor and other inhibitors of 5′-deiodinase activity activity were investigated. It was found that micromolar concentrations of, in order of increasing potency, 3,5-diiodotyrosine, thyroxine, 3,3′,5′-tri-iodothyronine and 3′,5′-di-iodothyronine significantly enhanced binding of 5-[125I]iodo-6-propyl-2-thiouracil to the enzyme preparation. This stimulation was not seen in the presence of 1 mM dithiothreitol, 0.1 mM-6-propyl-2-thiouracil, 0.1 mM-6-propyl-2-thiouracil, 0.1 M-2-mercapto-1-methylimidazole or 1 mM-sodium sulphite. These results support the hypothesis that thiouracil derivatives inhibit 5′-deiodinase activity by forming a mixed disulphide with an intermediate enzyme complex, probably a sulphenyl iodide.

scholarly journals The effect of phenobarbital on the submicrosomal distribution of uridine diphosphate glucuronyltransferase from rat liver

1970 ◽  
Vol 117 (2) ◽  
pp. 319-324 ◽  
Author(s):  
G. J. Mulder
Keyword(s):  
Enzyme Activity ◽  
Density Gradient ◽  
Rat Liver ◽  
Microsomal Fraction ◽  
Specific Activity ◽  
Sucrose Density Gradient ◽  
Male Rats ◽  
Uridine Diphosphate ◽  
Triton X

1. The detergent Triton X-100 activates UDP glucuronyltransferase from rat liver in vitro six- to seven-fold with p-nitrophenol as substrate. The enzyme activity when measured in the presence of Triton X-100 is increased significantly by pretreatment of male rats with phenobarbital for 4 days (90mg/kg each day intraperitoneally). If no Triton X-100 is applied in vitro such an increase could not be shown. In all further experiments the enzyme activity was measured after activation by Triton X-100. 2. The Km of the enzyme for the substrate p-nitrophenol does not change on phenobarbital pretreatment. 3. When the microsomal fraction from the liver of untreated rats is subfractionated on a sucrose density gradient, 47% of the enzyme activity is recovered in the rough-surfaced microsomal fraction, which also has a higher specific activity than the smooth-surfaced fraction. 4. Of the increase in activity after the phenobarbital pretreatment 50% occurs in the smooth-surfaced fraction, 19% in the rough-surfaced fraction and 31% in the fraction located between the smooth- and rough-surfaced microsomal fractions on the sucrose density gradient. 5. The latency of the enzyme in vitro, as shown by the effect of the detergent Triton X-100, is discussed in relation to the proposed heterogeneity of UDP glucuronyltransferase.

In vitro characterization of rosiglitazone metabolites and determination of the kinetic parameters employing rat liver microsomal fraction

2011 ◽  
Vol 36 (3) ◽  
pp. 159-166 ◽  
Author(s):  
Leandro Augusto Calixto ◽  
Anderson Rodrigo Moraes de Oliveira ◽  
Valquíria Aparecida Polisel Jabor ◽  
Pierina Sueli Bonato
Keyword(s):  
Kinetic Parameters ◽  
Rat Liver ◽  
Microsomal Fraction ◽  
In Vitro Characterization ◽  
Liver Microsomal Fraction
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