scholarly journals Polyribosomes in isolated liver cells. Preparative procedures, effects of incubation and correlation with protein synthesis

1980 ◽  
Vol 186 (1) ◽  
pp. 35-45 ◽  
Author(s):  
A J Dickson ◽  
C I Pogson
Keyword(s):  
Protein Synthesis ◽  
Rat Liver ◽  
Isolated Hepatocytes ◽  
Liver Cells ◽  
Liver Protein ◽  
Isolated Cells ◽  
Isolated Liver Cells ◽  
Rat Liver Cells ◽  
Isolated Liver

Methods have been derived which permit the isolation of undergraded polyribosomes from isolated rat liver cells. Under the conditions used the polyribosome profile of hepatocytes immediately after isolation was essentially identical with that from intact liver. However, during incubation of cells in complex physiological media there was a progressive dissociation of polyribosomes. The addition of a variety of factors that produce reaggregation of polyribosomes in rat liver in vivo did not prevent dissociation during cell incubations. Although large polyribosomes were lost most rapidly, the albumin-synthesizing capacity of isolated cells was not selectively lost when compared with total protein synthesis. The significance of these results for the use of isolated hepatocytes in the study of liver protein synthesis is discussed.

Alterations in protein synthesis in rat liver cells by in vitro and in vivo exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin

1991 ◽  
Vol 42 (6) ◽  
pp. 1195-1201 ◽  
Author(s):  
Aoki Yasunobu ◽  
Ellen K. Silbergeld ◽  
Stephen R. Max ◽  
Bruce A. Fowler
Keyword(s):  
Protein Synthesis ◽  
Rat Liver ◽  
Liver Cells ◽  
Rat Liver Cells ◽  
Tetrachlorodibenzo P Dioxin

scholarly journals Effect of 4-hydroxypyrazole on tryptophan and formate metabolism in isolated rat liver cells

1982 ◽  
Vol 204 (1) ◽  
pp. 307-312 ◽  
Author(s):  
J S Cook ◽  
C I Pogson
Keyword(s):  
Liver Cells ◽  
Isolated Rat Liver ◽  
Formate Oxidation ◽  
Isolated Liver Cells ◽  
Rat Liver Cells ◽  
Isolated Liver ◽  
Isolated Rat ◽  
Formate Metabolism ◽  
In Cells

1. 4-Hydroxypyrazole inhibits flux through tryptophan 2.3-dioxygenase in cells. The inhibition is apparently non-competitive with Ki = 0.15 mM. 2. Hydroxypyrazole inhibits the oxidation of formate to CO2 in liver cells. 3. Glycollate, which generates H2O2, stimulates formate oxidation. This process is inhibited by 4-hydroxypyrazole. 4. Methionine stimulates formate oxidation in cells and this stimulation is insensitive to 4-hydroxypyrazole. 5. It is concluded that, in freshly isolated liver cells, formate oxidation proceeds by a pathway involving catalase. In vivo, or when methionine is added to cell incubations, the pathway of oxidation involves tetrahydrofolate, and is insensitive to catalase inhibitors. 6. Methionine at physiological concentrations inhibits the activity of tryptophan 2,3-dioxygenase in isolated liver cells.

Relationship between the resting metabolic rate and hepatic metabolism in rats: effect of hyperthyroidism and fasting for 24 hours

1992 ◽  
Vol 135 (1) ◽  
pp. 45-51 ◽  
Author(s):  
S. Iossa ◽  
G. Liverini ◽  
A. Barletta
Keyword(s):  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Resting Metabolic Rate ◽  
Hepatic Metabolism ◽  
Isolated Hepatocytes ◽  
Liver Cells ◽  
Isolated Liver Cells ◽  
Rat Liver Cells ◽  
The Relationship ◽  
Isolated Liver

ABSTRACT We have examined the relationship between the changes in resting metabolic rate (RMR) and those in hepatic metabolism induced by hyperthyroidism and fasting for 24 h. We found that hyperthyroidism induced a significant increase in RMR, while fasting for 24 h reduced RMR in euthyroid but not in hyperthyroid rats. We have also measured oxygen consumption in isolated hepatocytes from euthyroid and hyperthyroid rats, fed or fasted for 24 h. Hyperthyroidism induced an increase in oxygen consumption in rat liver cells; fasting for 24 h increased respiratory rates in isolated liver cells from euthyroid but not from hyperthyroid rats. The findings showed that hyperthyroidism and fasting for 24 h have opposite effects on RMR but similar effects on hepatic metabolism. The results also indicated that the increase in RMR found in hyperthyroid rats is partly due to an increase in hepatic metabolism, while no correlation exists between variations in resting and hepatic metabolism induced by 24-h fasting. Journal of Endocrinology (1992) 135, 45–51

Fractionation of isolated liver cells after disruption with a nitrogen bomb and sonication

1982 ◽  
Vol 57 (1) ◽  
pp. 1-13
Author(s):  
F. Autuori ◽  
U. Brunk ◽  
E. Peterson ◽  
G. Dallner
Keyword(s):  
Rat Liver ◽  
Sucrose Gradient ◽  
Divalent Cations ◽  
Liver Cells ◽  
Cell Disruption ◽  
Isolated Liver Cells ◽  
Discontinuous Sucrose Gradient ◽  
Microsomal Membranes ◽  
Isolated Liver

Hepatocytes from rat liver were prepared by perfusion with collagenase, and rough and smooth microsomes and mitochondria were prepared after cell disruption. By applying 1000 lb/in2 (1 lb/in2 = 6.9 kPa) in a nitrogen bomb followed by decompression, 75% of the cells were disrupted after four consecutive treatments. Intact mitochondria, and rough and smooth microsomes with little contamination were prepared from the homogenate. A more rapid disruption was attained by a short sonication with a low output, thus increasing the efficiency of homogenization. The microsomal subfractions prepared from this homogenate were comparable to those obtained after decompression. Sonication resulted in smooth microsomes, which exhibited a higher contamination with non-microsomal membranes. These, however, were partly removed by additional centrifugation with a discontinuous sucrose gradient containing divalent cations.

scholarly journals Key role of l-alanine in the control of hepatic protein synthesis

1987 ◽  
Vol 241 (2) ◽  
pp. 491-498 ◽  
Author(s):  
D Pérez-Sala ◽  
R Parrilla ◽  
M S Ayuso
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Physiological Role ◽  
Chain Elongation ◽  
Liver Protein ◽  
Isolated Liver Cells ◽  
Metabolic Transformation ◽  
Hepatic Protein Synthesis

We investigated the effects of administration of single amino acids to starved rats on the regulation of protein synthesis in the liver. Of all the amino acids tested, only alanine, ornithine and proline promoted statistically significant increases in the extent of hepatic polyribosome aggregation. The most effective of these was alanine, whose effect of promoting polyribosomal aggregation was accompanied by a decrease in the polypeptide-chain elongation time. The following observations indicate that alanine plays an important physiological role in the regulation of hepatic protein synthesis. Alanine was the amino acid showing the largest decrease in hepatic content in the transition from high (fed) to low (starved) rates of protein synthesis. The administration of glucose or pyruvate is also effective in increasing liver protein synthesis in starved rats, and their effects were accompanied by an increased hepatic alanine content. An increase in hepatic ornithine content does not lead to an increased protein synthesis, unless it is accompanied by an increase of alanine. The effect of alanine is observed either in vivo, in rats pretreated with cycloserine to prevent its transamination, or in isolated liver cells under conditions in which its metabolic transformation is fully impeded.

Antiketogenic effect of glucose per se in vivo in man and in vitro in isolated rat liver cells

Metabolism ◽  
1986 ◽  
Vol 35 (7) ◽  
pp. 608-613 ◽  
Author(s):  
J.P. Riou ◽  
M. Beylot ◽  
M. Laville ◽  
L. De Parscau ◽  
J. Delinger ◽  
...  
Keyword(s):  
Rat Liver ◽  
Liver Cells ◽  
Isolated Rat Liver ◽  
Rat Liver Cells ◽  
Per Se ◽  
Effect Of Glucose ◽  
Isolated Rat

scholarly journals MTrasT24, a metallothionein-ras fusion gene, modulates expression in cultured rat liver cells of two genes associated with in vivo liver cancer.

1988 ◽  
Vol 85 (2) ◽  
pp. 344-348 ◽  
Author(s):  
Y. C. Li ◽  
T. Seyama ◽  
A. K. Godwin ◽  
T. S. Winokur ◽  
R. M. Lebovitz ◽  
...  
Keyword(s):  
Liver Cancer ◽  
Rat Liver ◽  
Fusion Gene ◽  
Liver Cells ◽  
Rat Liver Cells

scholarly journals The effects L-leucine on the synthesis of urea, glutamate and glutamine by isolated rat liver cells

1975 ◽  
Vol 146 (2) ◽  
pp. 457-464 ◽  
Author(s):  
J M Mourão ◽  
J D McGivan ◽  
J B Chappell
Keyword(s):  
Amino Acids ◽  
Nitrogen Source ◽  
Glutamate Dehydrogenase ◽  
Rat Liver ◽  
Liver Cells ◽  
Carbamoyl Phosphate ◽  
Isolated Cells ◽  
Isolated Rat Liver ◽  
Rat Liver Cells ◽  
Isolated Rat

With either alanine or a mixture of 15 different amino acids as nitrogen source, the addition of L-leucine inhibited the synthesis of urea by isolated rat liver cells. With alanine present leucine promoted the production of glutamate and glutamine. Comparison of effects of leucine on soluble glutamate dehydrogenase, mitochondria and isolated cells supports the postulate that leucine exerts its effect through activation of glutamate dehydrogenase. It is suggested that this latter enzyme may not be as important for the production of NH3 for carbamoyl phosphate synthesis as has been considered hitherto.

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