scholarly journals Inhibitory effect of t-butyl hydroperoxide on mitochondrial oxidative phosphorylation in isolated rat hepatocytes

2007 ◽  
pp. 137-140
Author(s):  
P Křiváková ◽  
A Lábajová ◽  
Z Červinková ◽  
Z Drahota
Keyword(s):  
Oxidative Phosphorylation ◽  
Rat Hepatocytes ◽  
Inhibitory Effect ◽  
Experimental Conditions ◽  
Isolated Rat Hepatocytes ◽  
Butyl Hydroperoxide ◽  
Peroxidative Damage ◽  
Cell Energy ◽  
Uncoupling Of Oxidative Phosphorylation ◽  
Low Activity

Using high-resolution oxygraphy, we tested the changes of various parameters characterizing the mitochondrial energy provision system that were induced by peroxidative damage. In the presence of succinate as respiratory substrate, 3 mM t-butyl hydroperoxide increased respiration in the absence of ADP, which indicated partial uncoupling of oxidative phosphorylation. Low activity of coupled respiration was still maintained as indicated by the ADP-activated and oligomycin-inhibited respiration. However, during the incubation the phosphorylative capacity decreased as indicated by the continuous decrease of the mitochondrial membrane potential. Under these experimental conditions the maximum capacity of the succinate oxidase system was inhibited by 50% in comparison with values obtained in the absence of t-butyl hydroperoxide. Our data thus indicate that the oxygraphic evaluation of mitochondrial function represents a useful tool for evaluation of changes participating in peroxidative damage of cell energy metabolism.

scholarly journals Protective Effects of Saponin Mixture, Isolated from <i>Astragalus monspessulanus</i> subsp. <i>monspessulanus</i> on Tert-Butyl Hydroperoxide—Induced Oxidative Stress in Isolated Rat Hepatocytes

2015 ◽  
Vol 06 (06) ◽  
pp. 799-803 ◽  
Author(s):  
Magdalena Spasova Kondeva-Burdina ◽  
Viktor Bratkov ◽  
Rumyana Lubomirova Simeonova ◽  
Vessela Bisserova Vitcheva ◽  
Ilina Nikolaeva Krasteva ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Rat Hepatocytes ◽  
Protective Effects ◽  
Isolated Rat Hepatocytes ◽  
Butyl Hydroperoxide ◽  
Tert Butyl ◽  
Tert Butyl Hydroperoxide ◽  
Isolated Rat

scholarly journals Inhibition of oxidative metabolism by propionic acid and its reversal by carnitine in isolated rat hepatocytes

1986 ◽  
Vol 236 (1) ◽  
pp. 131-136 ◽  
Author(s):  
E P Brass ◽  
P V Fennessey ◽  
L V Miller
Keyword(s):  
Palmitic Acid ◽  
Propionic Acid ◽  
Oxidative Metabolism ◽  
Rat Hepatocytes ◽  
Inhibitory Effect ◽  
Acid Oxidation ◽  
Isolated Rat Hepatocytes ◽  
Pyruvate Oxidation ◽  
Metabolic Basis ◽  
Isolated Rat

The present study was designed to study the interaction of propionic acid and carnitine on oxidative metabolism by isolated rat hepatocytes. Propionic acid (10 mM) inhibited hepatocyte oxidation of [1-14C]-pyruvate (10 mM) by 60%. This inhibition was not the result of substrate competition, as butyric acid had minimal effects on pyruvate oxidation. Carnitine had a small inhibitory effect on pyruvate oxidation in the hepatocyte system (210 +/- 19 and 184 +/- 18 nmol of pyruvate/60 min per mg of protein in the absence and presence of 10 mM-carnitine respectively; means +/- S.E.M., n = 10). However, in the presence of propionic acid (10 mM), carnitine (10 mM) increased the rate of pyruvate oxidation by 19%. Under conditions where carnitine partially reversed the inhibitory effect of propionic acid on pyruvate oxidation, formation of propionylcarnitine was documented by using fast-atom-bombardment mass spectroscopy. Propionic acid also inhibited oxidation of [1-14C]palmitic acid (0.8 mM) by hepatocytes isolated from fed rats. The degree of inhibition caused by propionic acid was decreased in the presence of 10 mM-carnitine (41% inhibition in the absence of carnitine, 22% inhibition in the presence of carnitine). Propionic acid did not inhibit [1-14C]palmitic acid oxidation by hepatocytes isolated from 48 h-starved rats. These results demonstrate that propionic acid interferes with oxidative metabolism in intact hepatocytes. Carnitine partially reverses the inhibition of pyruvate and palmitic acid oxidation by propionic acid, and this reversal is associated with increased propionylcarnitine formation. The present study provides a metabolic basis for the efficacy of carnitine in patients with abnormal organic acid accumulation, and the observation that such patients appear to have increased carnitine requirements (‘carnitine insufficiency’).

Comparison of rat liver response to coumarin administered in vivo versus in vitro

1964 ◽  
Vol 206 (1) ◽  
pp. 229-238 ◽  
Author(s):  
Judith G. Pool ◽  
C. F. Borchgrevink
Keyword(s):  
Amino Acid ◽  
Oxidative Phosphorylation ◽  
Vitamin K ◽  
Inhibitory Effect ◽  
Factor Vii ◽  
General Effect ◽  
Liver Slices ◽  
Cell Energy

Warfarin added to incubated liver slices inhibits the synthesis of factor VII (proconvertin) in proportion to the log of its concentration; surprisingly, it has the same inhibitory effect on the transport and incorporation of amino acid into protein of the liver slices. This latter finding seems to support the frequently proposed concept that vitamin K has a role in oxidative phosphorylation and that coumarin compounds, by antagonizing vitamin K, uncouple oxidative phosphorylation and thus have a general effect on cell energy supply. However, when we studied the liver of rats depleted of vitamin K the same effect was not seen. Liver slices from such animals produced little factor VII but they incorporated amino acid at the normal rate. Furthermore, administration of warfarin in vivo had the same result as vitamin K depletion: a fall in circulating prothrombin complex but no decrease in either labeling of plasma proteins by intravenous C14-amino acid or incorporation of amino acid into subsequently excised liver slices. There is thus a striking discrepancy between the action of warfarin administered in vitro and that administered in vivo.

Studies on regulatory mechanisms of heme biosynthesis in hepatocytes from normal and experimental-diabetic rats. Role of insulin

1990 ◽  
Vol 68 (6) ◽  
pp. 914-921 ◽  
Author(s):  
Eduardo T. Cánepa ◽  
Elena B. C. Llambías ◽  
Moisés Grinstein
Keyword(s):  
Aminolevulinic Acid ◽  
Rat Hepatocytes ◽  
Isolated Hepatocytes ◽  
Inhibitory Effect ◽  
Diabetic Rats ◽  
Significant Inhibition ◽  
Diabetic Rat ◽  
Experimental Conditions ◽  
Cytochrome P 450

In the present work we demonstrate that insulin decreases the phenobarbital-induced activities of δ-aminolevulinic acid synthase and ferrochelatase in isolated hepatocytes from normal and experimental-diabetic rats. Insulin concentrations required to produce significant inhibition in diabetic hepatocytes were higher than in normal cells. Under similar experimental conditions, insulin decreased the basal activities of δ-aminolevulinic acid synthase and ferrochelatase in hepatocytes from normal rats; no inhibitory effect was observed on the basal activity of δ-aminolevulinic acid synthase in hepatocytes from diabetic rats. Cytochrome P-450 content of both normal and diabetic cells was not affected by insulin in absence or presence of phenobarbital. The inhibitory action of insulin was exerted even when effective concentrations of glucagon, dexamethasone, or 8-(p-chlorophenylthio)-cAMP were present.Key words: δ-aminolevulinic acid synthase, ferrochelatase, cAMP, insulin, diabetic rat hepatocytes.

scholarly journals Regulation of heparan sulphate metabolism by adenosine 3′:5′-cyclic monophosphate in hepatocytes in culture

1980 ◽  
Vol 192 (2) ◽  
pp. 395-402 ◽  
Author(s):  
Perumana R. Sudhakaran ◽  
Wolfgang Sinn ◽  
Kurt von Figura
Keyword(s):  
Cyclic Amp ◽  
Heparan Sulphate ◽  
Molecular Size ◽  
Rat Hepatocytes ◽  
Inhibitory Effect ◽  
Dibutyryl Cyclic Amp ◽  
Isolated Rat Hepatocytes ◽  
Intracellular Compartments ◽  
Sulphated Glycosaminoglycans ◽  
Chain Synthesis

Freshly isolated rat hepatocytes maintained as monolayers in a serum-free medium synthesize sulphated glycosaminoglycans, most of which behave as heparan sulphate and are mainly distributed into intracellular compartments. Cyclic AMP, dibutyryl cyclic AMP, glucagon, noradrenaline, prostaglandin E1, and theophylline, all drugs and hormones known to increase intracellular cyclic AMP concentrations, decreased the incorporation of 35SO42− into heparan sulphate of intra-, extra- and peri-cellular pools. The inhibition mediated by dibutyryl cyclic AMP was dose-dependent and observed as early as 2h after exposure to the drug. In the presence of 1mm-dibutyryl cyclic AMP, incorporation of 35SO42− or [14C]glucosamine into heparan sulphate was decreased to 40–50%, suggesting that dibutyryl cyclic AMP interfered with the synthesis of heparan sulphate. This was further supported by pulse–chase experiments, where dibutyryl cyclic AMP had no effect on the degradation of sulphated glycosaminoglycans. Heparan sulphates synthesized and secreted into the extracellular pool in the presence of dibutyryl cyclic AMP were smaller in size, whereas the degree of sulphation and molecular size of the heparan sulphate chains released by β-elimination from these proteoglycans were not different from control values. In the presence of 1mm-cycloheximide, 35SO42− incorporation was decreased to 5%. Addition of p-nitrophenyl β-d-xyloside, an artificial acceptor of glycosaminoglycan chain synthesis, enhanced this incorporation to 18%. Dibutyryl cyclic AMP did not have any inhibitory effect on the synthesis of chains initiated on p-nitrophenyl β-d-xylosides. Incorporation of [3H]serine into heparan sulphate was not affected by dibutyryl cyclic AMP, whereas the degree of substitution of serine residues with heparan sulphate chains was less in heparan sulphate synthesized in the presence of dibutyryl cyclic AMP, suggesting that cyclic AMP exerts its effect on the metabolism of sulphated glycosaminoglycans by affecting the transfer of xylose on to the protein core.

Different relationships between cellular ATP and hepatic uptake among taurocholate, cholate, and organic anions

1993 ◽  
Vol 264 (4) ◽  
pp. G693-G701 ◽  
Author(s):  
M. Yamazaki ◽  
H. Suzuki ◽  
M. Hanano ◽  
Y. Sugiyama
Keyword(s):  
Initial Velocity ◽  
Organic Anion ◽  
Rat Hepatocytes ◽  
Inhibitory Effect ◽  
Organic Anions ◽  
Metabolic Inhibitors ◽  
Atp Content ◽  
Isolated Rat Hepatocytes ◽  
Total Uptake ◽  
Ca Uptake

Effects of cellular ATP content on uptake of cholate (CA) and organic anions (OAs; dibromosulfophthalein and benzylpenicillin) by isolated rat hepatocytes were investigated and were compared with that on taurocholate (TCA). Within 5 min of exposure to metabolic inhibitors (MIs), cellular ATP content fell to less than one-fifth of the control value, and the initial velocity of the total uptake of CA, Na(+)-independent uptake of CA and TCA, and the uptake of the OAs dropped in parallel with the decrease in cellular ATP. Whereas for the total uptake of TCA, the initial uptake remained virtually unchanged for a 5-min incubation with the MIs; a significant decrease in uptake was observed only after longer incubation times. Under variously ATP-decreased conditions, the initial velocity of the total uptake of CA and OAs was demonstrated to have a saturable relation to cellular ATP content, irrespective of exposure time to MIs. A difference in the Na(+)-dependent uptake of TCA and CA was also observed in terms of the inhibitory effect of the organic anion pravastatin. That is, the inhibition by pravastatin was partial for TCA uptake but almost complete for CA uptake. These findings suggest the following. 1) The mechanism of Na(+)-dependent CA uptake is different from that of TCA. 2) The Na(+)-independent uptake of bile acids and organic anions may be driven either by ATP hydrolysis (primary active transport) or by an as yet unidentified ion gradient that dissipates more rapidly than the Na+ gradient.

Inhibition of GSH efflux from rat liver by methionine: effects of GSH synthesis in cells and perfused organ

1990 ◽  
Vol 258 (6) ◽  
pp. G967-G973 ◽  
Author(s):  
J. C. Fernandez-Checa ◽  
T. Maddatu ◽  
M. Ookhtens ◽  
N. Kaplowitz
Keyword(s):  
Rat Liver ◽  
Reduced Glutathione ◽  
Rat Hepatocytes ◽  
Inhibitory Effect ◽  
Perfused Liver ◽  
Isolated Rat Hepatocytes ◽  
Dependent Inhibition ◽  
Krebs Henseleit Buffer ◽  
Isolated Rat ◽  
In Cells

The inhibition of efflux of intracellular reduced glutathione (GSH) by methionine was determined in isolated rat hepatocytes suspended either in Krebs-Henseleit buffer or in modified Fisher's medium. Methionine (1 mM) added to Krebs-Henseleit suspensions of isolated rat hepatocytes inhibited GSH efflux, with greater retention of GSH in the cells compared with control. Results were similar with methionine and 0.3 mM propargylglycine cystathionase inhibitor), suggesting no net synthesis of GSH from methionine. In Fisher's medium, the inhibitory effect of methionine on GSH efflux was masked due to increasing cellular GSH; however, the inhibitory effect of methionine was unmasked by propargylglycine, which prevented the utilization of methionine for GSH synthesis. The addition of serine (0.1 mM) to methionine in Krebs-Henseleit buffer raised cellular GSH, overcoming the inhibition of GSH efflux. In the perfused liver, infusion of 1 and 5 mM methionine initially inhibited GSH efflux, but the inhibition was reversed with continued methionine infusion. After removal of methionine, GSH efflux increased immediately. The reversal and rebound were blocked by propargylglycine, revealing concentration-dependent inhibition of sinusoidal GSH efflux by methionine. Thus, when methionine is utilized to promote GSH synthesis, its inhibitory effect on GSH efflux tends to be overcome.

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