scholarly journals Formation and utilization of 3-hydroxy-3-methylglutarate in liver mitochondria of starved and streptozotocin-diabetic rats

1978 ◽  
Vol 172 (3) ◽  
pp. 371-375 ◽  
Author(s):  
R Deana ◽  
M Fabbro ◽  
F Rigoni
Keyword(s):  
Guinea Pig ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Diabetic Rats ◽  
Rat Liver Mitochondria ◽  
Streptozotocin Diabetic Rats ◽  
Coa Hydrolase

Kidney and liver mitochondria of rat, rabbit and guinea pig are able to transform 3-hydroxy-3-methylglutarate into acetoacetate, whereas ox liver mitochondria and rat mitochondria of heart, diaphragm and brain do not exhibit such an activity. Starvation and streptozotocin treatment decreases the formation of acetoacetate from 3-hydroxy-3-methylglutarate. Addition of acetoacetate and succinate to the incubation media of mitochondria results in a decrease in the transformation of 3-hydroxy-3-methylglutarate into acetoacetate. A 3-hydroxy-3-methylglutaryl-CoA hydrolase is present in rat liver mitochondria; the activity does not show appreciable changes after starvation or streptozotocin treatment.

Inhibition of Rat Liver Mitochondrial 3-hydroxy-3-methylglutaryl-CoA Lyase by Succinyl-CoA

1979 ◽  
Vol 56 (3) ◽  
pp. 251-254
Author(s):  
Renzo Deana ◽  
Fernanda Rigoni ◽  
Lauro Galzigna
Keyword(s):  
Rat Liver ◽  
Competitive Inhibition ◽  
Liver Mitochondria ◽  
Diabetic Rats ◽  
Rat Liver Mitochondria ◽  
Lyase Activity ◽  
Streptozotocin Diabetic Rats

1. Succinyl-CoA inhibits 3-hydroxy-3-methylglutaryl-CoA lyase (EC 4.1.3.4) when added to purified preparations of the enzyme. 2. The apparent Ki value is 2·1 × 10−4 mol/l and the inhibition has the features of a partially competitive inhibition. 3. The effect of succinyl-CoA both added and enzymically produced on the lyase activity of sonically disrupted rat liver mitochondria results in decreased acetoacetate formation. 4. This occurs with mitochondria obtained from normal, starved and streptozotocin-diabetic rats. Riassunto 1. Il succinilCoA inibisce la 3-idrossi-3-metilglutarilCoA liasi (EC 4.1.3.4) se viene aggiunto a preparazioni di enzima purificato. 2. Il valore della Ki è 2·1 × 10−4 mol/l ed i dati indicano una inibizione parzialmente competitiva. 3. Il succinilCoA, aggiunto o prodotto enzimaticamente, provoca una diminuzione nella produzione di acetoacetato nei mitocondri sonicati di fegato di ratto. 4. Lo stesso fenomeno si verifica con mitocondri di ratti normali, digiuni e diabetici da streptozotocina.

Evidence for the Biosynthetic Difference between Isolated Mitochondria and Microsomes from Guinea-Pig and Rat Liver Regarding Lysophospharidic Acid, Phosphatidic Acid, CDP-Diglyceride, Phosphatidylglycerol, and Cardiolipin

1974 ◽  
Vol 52 (10) ◽  
pp. 936-939 ◽  
Author(s):  
J. B. Davidson ◽  
N. Z. Stanacev
Keyword(s):  
Guinea Pig ◽  
Phosphatidic Acid ◽  
Rat Liver ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Marker Enzymes ◽  
Synthetic Enzymes ◽  
Isolated Mitochondria ◽  
Significant Difference ◽  
Nadph Cytochrome C Reductase

The enzymatic activities of marker enzymes (NADPH – cytochrome c reductase and glucose-6-phosphatase) and synthetic enzymes (acyl-CoA:sn-glycero-3-phosphate acyltransferase, CTP:sn-3-phosphatidic acid cytidyltransferase, and CDP-diglyceride:sn-glycero-3-phosphate phosphatidyltransferase) were measured in both isolated mitochondria and microsomes from liver of guinea pig and rat. Results thus obtained show a significant difference in activities of these enzymes between subcellular particles within species and between two examined species. The activity of acyl-CoA:glycero-3-phosphate acyltransferase in guinea-pig mitochondria parallels the activity of microsomal marker enzymes in this fraction, while in rat liver mitochondria the activity is relatively higher and cannot be accounted for by the microsomal content as determined by marker enzymes. Implications of these results regarding mitochondrial autonomy in the biosynthesis of polyglycero-phosphatides and their precursors are discussed.

Biochemistry of Polyglycerophosphatides. Effect of Divalent Cations on the Biosynthesis and Composition of Polyglycerophosphatides in Isolated Mitochondria

1973 ◽  
Vol 51 (3) ◽  
pp. 274-285 ◽  
Author(s):  
Z. Domazet ◽  
L. Stuhne-Sekalec ◽  
J. B. Davidson ◽  
N. Z. Stanacev
Keyword(s):  
Guinea Pig ◽  
Rat Liver ◽  
Mitochondrial Membrane ◽  
Divalent Cations ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Guinea Pig Heart ◽  
Isolated Mitochondria ◽  
Membrane Bound

The effect of the addition of divalent cations on the formation of phosphatidylglycerophosphate, phosphatidylglycerol, and cardiolipin in isolated mitochondria from rat liver and guinea pig heart was studied. Although it was confirmed that the biosynthesis of phosphatidylglycerol in rat liver mitochondria does not require the addition of divalent cations, the addition of Mn2+ and Mg2+ has a profound effect on the level of synthesis and composition of polyglycerophosphatides. By developing a method for the preparation of membrane-bound labeled phosphatidylglycerol and an assay for the quantitative determination of polyglycerophosphatides, the high conversion of phosphatidylglycerol-2′-3H to cardiolipin-3H was established only in the presence of Mn2+ and/or Mg2+. Zn2+ and Ca2+, in the concentration tested, did not stimulate this conversion, nor were they inhibitory. In addition, the association of formed cardiolipin-3H with the mitochondrial membrane was demonstrated. Some implications of these findings are discussed.

scholarly journals Phenethylbiguanide and the inhibition of hepatic gluconeogenesis in the guinea pig

1974 ◽  
Vol 144 (1) ◽  
pp. 49-57 ◽  
Author(s):  
Korechika Ogata ◽  
Mireille Jomain-Baum ◽  
Richard W. Hanson
Keyword(s):  
Guinea Pig ◽  
Rat Liver ◽  
Time Course ◽  
Liver Mitochondria ◽  
Inhibitory Effect ◽  
Progressive Increase ◽  
Rat Liver Mitochondria ◽  
Pig Liver ◽  
High Concentrations ◽  
Guinea Pig Liver

1. Phenethylbiguanide inhibits the synthesis of phosphoenolpyruvate from malate or 2-oxoglutarate by isolated guinea-pig liver mitochondria. This inhibition is time- and concentration-dependent, with the maximum decrease in the rate of phosphoenolpyruvate synthesis (80%) evident after 10min of incubation with 1mm-phenethylbiguanide. 2. The phosphorylation of ADP by these mitochondria is also inhibited at increasing concentrations of phenethylbiguanide and there is a progressive increase in AMP formation. Guinea-pig liver mitochondria are more sensitive to this inhibition in oxidative phosphorylation caused by phenethylbiguanide than are rat liver mitochondria. 3. Simultaneous measurements of O2 consumption and ADP phosphorylation with guinea-pig liver mitochondria oxidizing malate plus glutamate in State 3 indicated that phenethylbiguanide at low concentrations (0.1mm) inhibits respiration at Site 1. At higher phenethylbiguanide concentrations Site 2 is also inhibited. 4. Gluconeogenesis from lactate, pyruvate, alanine and glycerol by isolated perfused guinea-pig liver is inhibited to various degrees by phenethylbiguanide. Alanine is the most sensitive to inhibition (60% inhibition of the maximum rate by 0.1mm-phenethylbiguanide), whereas glycerol is relatively insensitive (25% inhibition at 4mm). 5. Gluconeogenesis from lactate and pyruvate by perfused rat liver was also inhibited by phenethylbiguanide, but only at high concentrations (8mm). Unlike guinea-pig liver, the inhibitory effect of phenethylbiguanide on rat liver was reversible after the termination of phenethylbiguanide infusion. 6. The time-course of inhibition of gluconeogenesis from the various substrates used in this study indicated a time-dependency which was related in part to the concentration of infused phenethylbiguanidine. This time-course closely paralleled that noted for the inhibition by phenethylbiguanide of phosphoenolpyruvate synthesis in isolated guinea-pig liver mitochondria.

Effects of 5-5'-Diphenyl-2-thiohydantoin (DPTH) and Thyroxine on the Ultrastructure and Chemical Composition of Rat Liver

1971 ◽  
Vol 29 ◽  
pp. 570-571
Author(s):  
E. A. Elfont ◽  
R. B. Tobin ◽  
D. G. Colton ◽  
M. A. Mehlman
Keyword(s):  
Chemical Composition ◽  
Rat Liver ◽  
Future Study ◽  
Mode Of Action ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Effective Inhibitor ◽  
Biochemical Effects ◽  
Glycerophosphate Dehydrogenase ◽  
Stimulation Of

Summary5,-5'-diphenyl-2-thiohydantoin (DPTH) is an effective inhibitor of thyroxine (T4) stimulation of α-glycerophosphate dehydrogenase in rat liver mitochondria. Because this finding indicated a possible tool for future study of the mode of action of thyroxine, the ultrastructural and biochemical effects of DPTH and/or thyroxine on rat liver mere investigated.Rats were fed either standard or DPTH (0.06%) diet for 30 days before T4 (250 ug/kg/day) was injected. Injection of T4 occurred daily for 10 days prior to sacrifice. After removal of the liver and kidneys, part of the tissue was frozen at -50°C for later biocheailcal analyses, while the rest was prefixed in buffered 3.5X glutaraldehyde (390 mOs) and post-fixed in buffered 1Z OsO4 (376 mOs). Tissues were embedded in Araldlte 502 and the sections examined in a Zeiss EM 9S.Hepatocytes from hyperthyroid rats (Fig. 2) demonstrated enlarged and more numerous mitochondria than those of controls (Fig. 1). Glycogen was almost totally absent from the cytoplasm of the T4-treated rats.

Energy and Antioxidant Status of Rat Liver Mitochondria during Hypoxia- Reoxygenation of Different Duration

2016 ◽  
Vol 7 (4) ◽  
pp. 349-361
Author(s):  
Olga A. Gonchar ◽  
Valentina I. Nosar ◽  
Larisa. V. Bratus ◽  
I. N. Tymchenko ◽  
N. N. Steshenko ◽  
...  
Keyword(s):  
Rat Liver ◽  
Antioxidant Status ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Hypoxia Reoxygenation
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