scholarly journals The development of gluconeogenesis in rat liver. Experiments in vivo

1969 ◽  
Vol 113 (4) ◽  
pp. 651-657 ◽  
Author(s):  
Helen Philippidis ◽  
F. J. Ballard
Keyword(s):  
Rat Liver ◽  
Redox State ◽  
Fold Increase ◽  
Newborn Rats ◽  
Foetal Liver ◽  
Tracer Experiments ◽  
Newborn Animals

1. The injection of substrate amounts of lactate into newborn rats produced an increase in the concentration of phosphoenolpyruvate in liver. Similar experiments with foetal rats showed no increase in phosphoenolpyruvate concentration although pyruvate formation was observed. 2. The administration of pyruvate to foetal rats was also without effect on the hepatic phosphoenolpyruvate concentration, although a 20-fold increase in this was observed when pyruvate was injected into newborn animals. 3. Analogous experiments with aspartate produced qualitatively similar differences between foetal and newborn rats. 4. When [14C]-lactate, -pyruvate or -aspartate was injected into foetal or newborn rats incorporation of radioactivity into liver glucose was observed only in the newborn animals. 5. Lactate/pyruvate ratios of 213 in foetal liver and 13·5 in the livers of newborn rats indicated a relatively reduced environment in the cytosol of foetal liver. This difference in redox state was illustrated experimentally by a greater conversion of pyruvate into lactate and an increased formation of malate in foetal liver. 6. Although both the substrate-loading and tracer experiments indicated a block in gluconeogenesis in foetal liver at the stage of conversion of oxaloacetate into phosphoenolpyruvate, gluconeogenesis was also hindered by a highly reduced environment.

scholarly journals The development of gluconeogenesis in rat liver. Effects of glucagon and ether

1970 ◽  
Vol 120 (2) ◽  
pp. 385-392 ◽  
Author(s):  
Helen Philippidis ◽  
F. J. Ballard
Keyword(s):  
Rat Liver ◽  
Redox State ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Fold Increase ◽  
Similar Increase ◽  
Ether Anaesthesia ◽  
Foetal Liver ◽  
Foetal Rat ◽  
Newborn Animals

1. Administration of glucagon to foetal rats produced a 10–15-fold increase in hepatic phosphoenolpyruvate carboxykinase activity together with a similar increase in the overall pathway of pyruvate conversion into glycogen in liver slices. 2. Glucagon was without effect on gluconeogenesis in vivo, which remained at approx. 0.1% of the incorporation as measured in newborn animals. 3. The apparent discrepancy between these results was due to the ether anaesthesia that was required for experimentation in vivo. Under conditions when minimal ether was used, the rates of labelling of glycogen from [3-14C]pyruvate in vivo were increased 10–20-fold and there was an additional stimulus by glucagon. 4. Ether anaesthesia produced a more reduced redox state of the foetal liver cytosol and lowered the ATP/ADP concentration ratio. 5. It is proposed that these effects are significant in the limitation of gluconeogenesis in the foetal rat liver, so that only with high phosphoenolpyruvate carboxykinase activity, high ATP concentration and a relatively oxidized cytosol redox state will a functional gluconeogenic pathway be present.

scholarly journals Control of the redox state of the nicotinamide–adenine dinucleotide couple in rat liver cytoplasm

1972 ◽  
Vol 126 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Marion Stubbs ◽  
R. L. Veech ◽  
H. A. Krebs
Keyword(s):  
Rat Liver ◽  
Redox State ◽  
Adenine Nucleotide ◽  
Adenine Nucleotides ◽  
Phosphoglycerate Kinase ◽  
Phosphorylation State ◽  
Crotyl Alcohol ◽  
Order Of Magnitude ◽  
The Individual

1. A study has been made of the ability of rat liver in vivo to maintain equilibrium in the combined glyceraldehyde 3-phosphate dehydrogenase, 3-phosphoglycerate kinase and lactate dehydrogenase reactions, i.e. in the system: [Formula: see text] Attempts were made to upset equilibrium. The [lactate]/[pyruvate] ratio was rapidly changed by injection of ethanol or crotyl alcohol, and the value of [ATP]/[ADP][HPO42-] was rapidly changed by injection of ethionine or carbonyl cyanide p-trifluoromethoxy-phenylhydrazone. 2. The concentrations of the metabolites occurring in the above equation were measured in freeze-clamped liver. 3. Although the injected agents caused large changes in the concentrations of the individual components, near-equilibrium in the system was maintained, as indicated by the fact that the value of [ATP]/[ADP][HPO42-], referred to as the phosphorylation state of the adenine nucleotides, measured directly agreed with the value calculated for equilibrium conditions from the above equation. 4. The results are discussed and taken to confirm that the order of magnitude of the value of the redox state of the cytoplasmic NAD couple in rat liver is controlled by the phosphorylation state of the adenine nucleotide system.

scholarly journals Studies on cystathionase activity in rat liver and brain during development. Effects of hormones and amino acids in vivo

1973 ◽  
Vol 136 (4) ◽  
pp. 1011-1015 ◽  
Author(s):  
Kirsti Heinonen
Keyword(s):  
Amino Acids ◽  
Enzyme Activity ◽  
Rat Brain ◽  
High Activity ◽  
Rat Liver ◽  
Newborn Rats ◽  
Postnatal Rats

High activity of cystathionase was present in rat liver but only low amounts of activity in rat brain during development. Triamcinolone had no effect on liver cystathionase activity in foetuses but increased the enzyme activity significantly in postnatal rats. l-Thyroxine decreased liver cystathionase activity significantly in newborn rats; administration of pyridoxal 5′-phosphate did not prevent this effect. l-Methionine significantly increased liver cystathionase activity in newborn rats.

scholarly journals Unacylated ghrelin does not alter mitochondrial function, redox state and triglyceride content in rat liver in vivo

2015 ◽  
Vol 4 ◽  
pp. 1-7 ◽  
Author(s):  
Gianluca Gortan Cappellari ◽  
Michela Zanetti ◽  
Annamaria Semolic ◽  
Pierandrea Vinci ◽  
Giulia Ruozi ◽  
...  
Keyword(s):  
Rat Liver ◽  
Mitochondrial Function ◽  
Redox State ◽  
Unacylated Ghrelin ◽  
Triglyceride Content

scholarly journals In vivo assessment of intracellular redox state in rat liver using hyperpolarized [1‐ 13 C]Alanine

2017 ◽  
Vol 77 (5) ◽  
pp. 1741-1748 ◽  
Author(s):  
Jae Mo Park ◽  
Chalermchai Khemtong ◽  
Shie‐Chau Liu ◽  
Ralph E. Hurd ◽  
Daniel M. Spielman
Keyword(s):  
Rat Liver ◽  
Redox State ◽  
In Vivo Assessment ◽  
Intracellular Redox

scholarly journals Regulation of glycine catabolism in rat liver mitochondria

1992 ◽  
Vol 283 (2) ◽  
pp. 435-439 ◽  
Author(s):  
M Jois ◽  
H S Ewart ◽  
J T Brosnan
Keyword(s):  
Rat Liver ◽  
Fold Increase ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Mitochondrial Matrix ◽  
Isolated Rat Liver ◽  
Matrix Volume ◽  
Isolated Rat ◽  
Stimulation Of

1. The catabolism of glycine was studied in isolated rat liver mitochondria by measuring release of 14CO2 from [1-14C]-glycine. Incubation of mitochondria in a medium containing 0.5 microM free Ca2+ resulted in an 8-fold increase in the rate of degradation of glycine. Intraperitoneal injection of glucagon (33 or 100 micrograms/100 g body wt.) 25 min before killing of rats also resulted in a 3-fold or 10-fold (depending on dosage) increase in the rate of catabolism of glycine. 2. Both the stimulation by free Ca2+ and that by injection of glucagon in vivo were dependent on phosphate in the incubation medium. This requirement for phosphate was specific, as replacement of phosphate by other permeant anions such as thiocyanate and acetate did not permit the stimulation. The phosphate-dependent stimulation of glycine catabolism by Ca2+ was also evident when mitochondria were incubated in the absence of K+. 3. Mitochondria isolated from rats previously injected with glucagon showed elevated rates of degradation of glycine even in the presence of rotenone, provided that regeneration of NAD+ was affected by providing acetoacetate. 4. Hypo-osmolarity of the medium markedly stimulated the rate of degradation of glycine by mitochondria. Although hypo-osmolarity-induced stimulation of glycine degradation was accompanied by parallel changes in mitochondrial matrix volume, no measurable changes in matrix volume were observed in mitochondria stimulated either by free Ca2+ (0.5 microM) or by injection of glucagon in vivo. Furthermore, Ca2+ stimulated glycine decarboxylation in mitochondria exposed to either hyper-osmolar (410 mosmol) or hypo-osmolar (210 mosmol) conditions. Although hyper-osmolarity decreased and hypo-osmolarity increased matrix volume, stimulation of glycine degradation by Ca2+ was not associated with any further changes in matrix volume. 5. These data demonstrate that the regulation of hepatic glycine oxidation by glucagon and by free Ca2+ is largely independent of changes in mitochondrial matrix volume.

scholarly journals Control of phosphatidylcholine synthesis and the regulatory role of choline kinase in rat liver. Evidence from essential-fatty acid-deficient rats

1978 ◽  
Vol 176 (2) ◽  
pp. 631-633 ◽  
Author(s):  
J P Infante ◽  
J E Kinsella
Keyword(s):  
Fatty Acid ◽  
Essential Fatty Acid ◽  
Rat Liver ◽  
Specific Activity ◽  
Fold Increase ◽  
Regulatory Role ◽  
Choline Kinase ◽  
Fatty Acid Deficiency

Choline kinase and phosphocholine cytidylytransferase catalyse the rate-limiting steps of the cytidine pathway for the synthesis of phosphatidylcholine [Infante (1977) Biochem. J. 167, 847–849]. Essential-fatty acid deficiency induces a 3.5-fold increase in the specific activity of choline kinase, whereas the specific activity of the cytidylytransferase remains unchanged in rat liver. This change in specific activity accounts for the calculated increase in flux through the cytidine pathway produced in vivo by the same dietary state [Trewhella & Collins (1973 Biochim. Biophys. Acta 296, 34–50], thus confirming the fact that choline kinase has a regulatory role in the cytidine pathway for the synthesis of phosphatidylcholine.

scholarly journals The role of prolactin and progesterone in the regulation of lipogenesis in maternal and foetal rat liver in vivo and in isolated hepatocytes during the last day of gestation

1986 ◽  
Vol 239 (1) ◽  
pp. 135-139 ◽  
Author(s):  
M Lorenzo ◽  
C Roncero ◽  
M Benito
Keyword(s):  
Rat Liver ◽  
Lipid Synthesis ◽  
Isolated Hepatocytes ◽  
Hepatic Lipogenesis ◽  
Treatment Conditions ◽  
Foetal Liver ◽  
Foetal Rat

The administration of progesterone on day 21 of gestation increases the rates of lipogenesis in the liver in vivo and in hepatocytes isolated from rats on day 22 of pregnancy. Bromocriptine administration increases the rates of hepatic lipogenesis in vivo, but has no effect on lipid synthesis in hepatocytes under the same treatment conditions. Concurrently, the administration of progesterone or bromocriptine on day 21 to the mother increases the rates of lipogenesis in the foetal liver in vivo on day 22. The rates of lipid synthesis in foetal isolated hepatocytes are increased by progesterone administration, but remain unchanged by bromocriptine.

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