scholarly journals Amino Acids and Insulin Control Autophagic Proteolysis through Different Signaling Pathways in Relation to mTOR in Isolated Rat Hepatocytes

2003 ◽  
Vol 279 (9) ◽  
pp. 8452-8459 ◽  
Author(s):  
Takumi Kanazawa ◽  
Ikue Taneike ◽  
Ryuichiro Akaishi ◽  
Fumiaki Yoshizawa ◽  
Norihiko Furuya ◽  
...  
Keyword(s):  
Amino Acids ◽  
Signaling Pathways ◽  
Rat Hepatocytes ◽  
Isolated Rat Hepatocytes ◽  
Insulin Control ◽  
Isolated Rat

Signalling pathways and combinatory effects of insulin and amino acids in isolated rat hepatocytes

2002 ◽  
Vol 269 (15) ◽  
pp. 3742-3750 ◽  
Author(s):  
Ulrike Krause ◽  
Luc Bertrand ◽  
Liliane Maisin ◽  
Maria Rosa ◽  
Louis Hue
Keyword(s):  
Amino Acids ◽  
Rat Hepatocytes ◽  
Signalling Pathways ◽  
Isolated Rat Hepatocytes ◽  
Isolated Rat

scholarly journals Comparison of the effects of various amino acids on glycogen synthesis, lipogenesis and ketogenesis in isolated rat hepatocytes

1991 ◽  
Vol 273 (1) ◽  
pp. 57-62 ◽  
Author(s):  
A Baquet ◽  
A Lavoinne ◽  
L Hue
Keyword(s):  
Amino Acids ◽  
Time Course ◽  
Glycogen Synthesis ◽  
Rat Hepatocytes ◽  
Isolated Rat Hepatocytes ◽  
Aminoisobutyric Acid ◽  
Malonyl Coa ◽  
Lag Period ◽  
Isolated Rat ◽  
Stimulation Of

Several amino acids were found to stimulate glycogen synthesis and lipogenesis, and to inhibit ketogenesis in isolated rat hepatocytes. When hepatocytes were incubated in the presence of 20 mM-glucose, the amino acids could be classified in decreasing order of efficiency as follows: glutamine and proline, alanine, aminoisobutyric acid, asparagine and histidine for stimulation of glycogen synthesis; glutamine, proline and alanine for stimulation of lipogenesis; proline and glutamine for inhibition of ketogenesis. The study of the time course revealed that the rates were not linear and were preceded by a lag period. In all conditions studied, glutamine and proline were found to have similar quantitative effects on glycogen synthesis and lipid metabolism. However, their effects differ qualitatively. Indeed, the effects of proline on glycogen synthesis, lipogenesis and glutamate and aspartate content were faster. Moreover, proline increased the hydroxybutyrate/acetoacetate ratio, whereas glutamine did not change it. Incubation of hepatocytes with aminoisobutyric acid or under hypo-osmotic conditions, which increased cell volume and mimicked the amino acid-induced stimulation of glycogen synthesis, had little effect on lipogenesis. In hepatocytes incubated without glucose, ketogenesis was inhibited, in decreasing order of efficiency, by alanine, asparagine, glutamine and proline. Under these conditions, glutamine increased, alanine decreased and asparagine did not affect the concentration of malonyl-CoA. This indicates that the latter cannot be responsible for the inhibition of ketogenesis by alanine and asparagine.

Time-dependent alterations in the pathway of glucose incorporation into glycogen in primary cultures of rat hepatocytes following glucose starvation

1988 ◽  
Vol 66 (2) ◽  
pp. 143-147 ◽  
Author(s):  
M. A. Parniak ◽  
N. Kalant
Keyword(s):  
Amino Acids ◽  
Glycogen Synthesis ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Time Dependent ◽  
Glucose Starvation ◽  
Isolated Rat Hepatocytes ◽  
Glucose Incorporation ◽  
Gluconeogenic Substrates ◽  
Isolated Rat

Isolated rat hepatocytes maintained in primary culture were able to use glucose for glycogen synthesis by both direct and indirect mechanisms. Cells that had been isolated from fed animals and then cultured in the absence of glucose, but in the presence of gluconeogenic substrates such as pyruvate and amino acids, had decreased glycogen contents compared with similar cells that had been cultured in the presence of glucose. Upon reexposure to glucose, the glucose-starved cells showed time-dependent changes in the preferred pathway for the use of glucose for glycogen synthesis. These changes were noted either in the absence or presence of insulin; however, net accumulation of glycogen was observed only in the presence of the hormone.

scholarly journals Effects of amino acids, ammonia and leupeptin on protein synthesis and degradation in isolated rat hepatocytes

1978 ◽  
Vol 174 (2) ◽  
pp. 469-474 ◽  
Author(s):  
P O Seglen
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Protein Degradation ◽  
Specific Radioactivity ◽  
Rat Hepatocytes ◽  
Amino Acid Mixture ◽  
Acid Mixture ◽  
Isolated Rat Hepatocytes ◽  
Lysosomal Protein ◽  
Isolated Rat

Protein synthesis in isolated rat hepatocytes, as measured by the incorporation of [14C]-valine at constant specific radioactivity, proceeded at a rate of 0.3-0.5%/h in an unsupplemented medium, i.e. only about one-tenth the rate of protein degradation (4%/h). Leupeptin, which inhibits lysosomal protein degradation (previously found to be 75% of the total degradation in hepatocytes), had no effect on protein synthesis, showing that endogenous protein degradation supplied amino acids in excess of the substrate requirements for protein synthesis. The inhibition of protein synthesis by NH4Cl (another inhibitor of lysosomal protein degradation) as well as the stimulation by a physiological amino acid mixture must therefore represent indirect effects, either on general energy metabolism, or on unknown regulatory processes.

scholarly journals Re-activation by glutamate or aspartate of amino-oxyacetate-inhibited aspartate aminotransferase in vitro and in isolated hepatocytes

1981 ◽  
Vol 198 (1) ◽  
pp. 219-223 ◽  
Author(s):  
Neal W. Cornell ◽  
Kathryn E. Crow ◽  
Richard P. Whitefoot
Keyword(s):  
Amino Acids ◽  
Aspartate Aminotransferase ◽  
Rat Hepatocytes ◽  
Isolated Hepatocytes ◽  
Isolated Rat Hepatocytes ◽  
Whole Cells ◽  
Cell Extracts ◽  
Isolated Rat

Experiments with isolated rat hepatocytes and with cell extracts indicate, in contrast with previous reports, that pyruvate does not block or reverse the inhibition of aspartate aminotransferase (EC 2.6.1.1) by amino-oxyacetate. That inhibition, however, is partially overcome by glutamate or aspartate either in cell extracts or in whole cells incubated with substrate combinations that cause accumulation of those amino acids.

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