Oxidative energy metabolism in germ-free and conventional rat liver mitochondria

1975 ◽  
Vol 228 (2) ◽  
pp. 526-529 ◽  
Author(s):  
DL Sewell ◽  
BS Wostmann ◽  
C Gairola ◽  
MI Aleem
Keyword(s):  
Wistar Rats ◽  
Liver Mitochondria ◽  
The State ◽  
Rat Liver Mitochondria ◽  
Succinate Oxidation ◽  
Germ Free ◽  
Adult Rat ◽  
Respiration Rates ◽  
Oxidative Energy Metabolism ◽  
Beta Hydroxybutyrate

The ADP:O ratios and State 3 (ADP-stimulated) and State 4 (controlled) rates of succinate, beta-hydroxybutyrate, isocitrate, glutamate, pyruvate + malate, alpha-ketoglutarate, and ascorbate + N,N,N',N'-tetramethylphenylenediamine (TMPD) oxidation were examined in liver mitochondria from germ-free and conventional rats of both Lobund Wistar (100-day-old) and Fisher (120-day-old) strains. The State 3 respiration rates of isolated mitochondria from germ-free and conventional rats were comparable except for the rate of succinate oxidation in the Wistar rats, which was significantly lower (approx. 10%). The State 4 respiration rates were generally lower in mitochondria isolated from germ-free Fisher rats (approx. 8%) and significantly lower (approx. 18%) in germ-free Wistar rats. The ADP:O ratios were similar in germ-free and conventional rats. Serum thyroxine concentrations indicated delayed maturation of thyroid function in young germ-free rats, but adult animals had concentrations similar to those found in conventional rats. The results indicate that, although absence of a microflora results in a 20-30% reduction in metabolic rate, the germ-free state has little influence on the functional respiration or oxidative phosphorylation of mitochondria isolated from the liver of the adult rat.

Inhibition of Succinic Dehydrogenase and F0F1-ATP Synthase by 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic Acid (DIDS)

1997 ◽  
Vol 52 (11-12) ◽  
pp. 799-806 ◽  
Author(s):  
Celene F. Bernardes ◽  
Jose R. Meyer-Fernandes ◽  
Orlando B. Martins ◽  
Anibal E. Vercesi
Keyword(s):  
Succinic Dehydrogenase ◽  
Atp Synthesis ◽  
Liver Mitochondria ◽  
Disulfonic Acid ◽  
Rat Liver Mitochondria ◽  
Dependent Manner ◽  
Submitochondrial Particles ◽  
Succinate Oxidation ◽  
Hydrolytic Activities ◽  
Dose Dependent

Abstract This study shows that incubation of rat liver mitochondria in the presence of the thiol/ amino reagent 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DID S) is followed by inhibition of both succinate supported respiration and oxidative phosphorylation. Half-maximal inhibition of succinic dehydrogenase activity and succinate oxidation by mitochondria was attained at 55.3 and 60.8 μm DIDS, respectively. DIDS did inhibit the net ATP synthesis and ATP ⇔ [32P]Pi exchange reaction catalyzed by submitochondrial particles in a dose-dependent manner (Ki= 31.7 μm and Ki = 32.7 μm), respectively. The hydrolytic activities of uncoupled heart submitochondrial particles and purified F 1 -ATPase were also inhibited 50% by 31.9 and 20.9 μm DIDS, respectively.

scholarly journals Hepatic ketogenesis in newborn pigs is limited by low mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase activity

1994 ◽  
Vol 298 (1) ◽  
pp. 207-212 ◽  
Author(s):  
P H Duée ◽  
J P Pégorier ◽  
P A Quant ◽  
C Herbin ◽  
C Kohl ◽  
...  
Keyword(s):  
Rat Liver ◽  
Liver Mitochondria ◽  
Oxidation Products ◽  
Rat Liver Mitochondria ◽  
Acid Oxidation ◽  
Acetyl Coa ◽  
Pig Liver ◽  
Adult Rat ◽  
Malonyl Coa ◽  
Cpt I

In newborn-pig hepatocytes, the rate of oleate oxidation is extremely low, despite a very low malonyl-CoA concentration. By contrast, the sensitivity of carnitine palmitoyltransferase (CPT) I to malonyl-CoA inhibition is high, as suggested by the very low concentration of malonyl-CoA required for 50% inhibition of CPT I (IC50). The rates of oleate oxidation and ketogenesis are respectively 70 and 80% lower in mitochondria isolated from newborn-pig liver than from starved-adult-rat liver mitochondria. Using polarographic measurements, we showed that the oxidation of oleoyl-CoA and palmitoyl-L-carnitine is very low when the acetyl-CoA produced is channelled into the hydroxymethylglutaryl-CoA (HMG-CoA) pathway by addition of malonate. In contrast, the oxidation of the same substrates is high when the acetyl-CoA produced is directed towards the citric acid cycle by addition of malate. We demonstrate that the limitation of ketogenesis in newborn-pig liver is due to a very low amount and activity of mitochondrial HMG-CoA synthase as compared with rat liver mitochondria, and suggest that this could promote the accumulation of acetyl-CoA and/or beta-oxidation products that in turn would decrease the overall rate of fatty acid oxidation in newborn- and adult-pig livers.

scholarly journals Peroxidative damage of mitochondrial respiration is substrate-dependent

2009 ◽  
pp. 685-692
Author(s):  
R Endlicher ◽  
P Křiváková ◽  
H Rauchová ◽  
H Nůsková ◽  
Z Červinková ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Liver Mitochondria ◽  
Inhibitory Effect ◽  
Rat Liver Mitochondria ◽  
Succinate Oxidation ◽  
Peroxidative Damage ◽  
Palmitoyl Carnitine ◽  
Low Concentrations ◽  
Tert Butyl Hydroperoxide ◽  
Strong Inhibitory Effect

The concentration-dependence of tert-butyl hydroperoxide (BHP) inhibitory effect on oxygen consumption in isolated rat liver mitochondria was measured in the presence of various respiratory substrates. Strong inhibitory effect at low concentrations of BHP (15-30 µM) was found for oxoglutarate and palmitoyl carnitine oxidation. Pyruvate and glutamate oxidation was inhibited at higher concentrations of BHP (100-200 µM). Succinate oxidation was not affected even at 3.3 mM BHP. Determination of mitochondrial membrane potential has shown that in the presence of NADH-dependent substrates the membrane potential was dissipated by BHP but was completely restored after addition of succinate. Our data thus indicate that beside peroxidative damage of complex I also various mitochondrial NADH-dependent dehydrogenases are inhibited, but to a different extent and with different kinetics. Our data also show that succinate could be an important nutritional substrate protecting hepatocytes during peroxidative damage.

THE INHIBITION OF OXIDATIVE AND PHOSPHORYLATIVE ENZYMES IN RAT LIVER MITOCHONDRIA BY AMINOAZOBENZENE DERIVATIVES

1960 ◽  
Vol 38 (1) ◽  
pp. 1-11 ◽  
Author(s):  
W. C. McMurray
Keyword(s):  
Cytochrome C ◽  
Rat Liver ◽  
Pyridine Nucleotide ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Succinate Oxidation ◽  
Metabolic Block ◽  
Liver Carcinogen ◽  
Mitochondrial Dehydrogenase Activity

The liver carcinogen, dimethylaminoazobenzene, inhibited in vitro the oxidation of a variety of pyridine nucleotide linked substrates of rat liver mitochondria without affecting the process of oxidative phosphorylation. Cytochrome c oxidase activity was not inhibited by the carcinogen, nor was the succinoxidase activity, but the phosphorylation accompanying succinate oxidation was uncoupled. Similar effects were noted with other aminoazobenzene derivatives, but did not appear to be correlated with the ability of the compounds to evoke tumors.The site of the respiratory inhibition by dimethylaminoazobenzene appears to be at the level between reduced pyridine nucleotide and cytochrome c in the respiratory chain. Mitochondrial dehydrogenase activity was not inhibited, while the oxidation of reduced diphosphopyridine nucleotide was markedly decreased. The reduction of the electron acceptor, ferricyanide, by pyridine nucleotide linked substrates was also strongly inhibited but the reduction of tetrazolium compounds was not affected. The latter observations suggest that dimethylaminoazobenzene produces a metabolic block between reduced flavin and cytochrome c in the mitochondrial electron transport system.

scholarly journals The inhibition of pyruvate and ls(+)-isocitrate oxidation by succinate oxidation in rat liver mitochondria

1969 ◽  
Vol 114 (3) ◽  
pp. 589-596 ◽  
Author(s):  
T. König ◽  
D. G. Nicholls ◽  
P. B. Garland
Keyword(s):  
Cytochrome B ◽  
Rat Liver ◽  
Rat Heart ◽  
Fold Increase ◽  
Liver Mitochondria ◽  
Inhibitory Effect ◽  
The Other ◽  
Rat Liver Mitochondria ◽  
Succinate Oxidation ◽  
Rapid Flow

1. The effects of succinate oxidation on pyruvate and also isocitrate oxidation by rat liver mitochondria were studied. 2. Succinate oxidation was without effect on pyruvate and isocitrate oxidation when respiration was maximally activated with ADP. 3. When respiration was partially inhibited by atractylate, succinate oxidation severely inhibited the oxidation of pyruvate and isocitrate. 4. This inhibitory effect of succinate was associated with a two- to three-fold increase in the reduction of mitochondrial NAD+ but no change in the reduction of cytochrome b. 5. It is concluded that, in the partially energy-controlled state, respiration is more severely inhibited at the first phosphorylating site than at the other two. 6. The effects of succinate oxidation are compared with those of palmitoylcarnitine oxidation. It is concluded that a rapid flow of electrons directly into the respiratory chain at the level of cytochrome b is in itself inadequate to inhibit the oxidation of intramitochondrial NADH. 7. The effects of succinate oxidation on pyruvate oxidation were similar in rat heart and liver mitochondria.

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