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

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.

1991 ◽  
Vol 273 (1) ◽  
pp. 57-62 ◽  
Author(s):  
A Baquet ◽  
A Lavoinne ◽  
L Hue

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.


1987 ◽  
Vol 246 (2) ◽  
pp. 449-454 ◽  
Author(s):  
A Lavoinne ◽  
H A Buc ◽  
S Claeyssens ◽  
M Pinosa ◽  
F Matray

Incubation of hepatocytes from 24 h-starved rats in the presence of 0.5 mM-adenosine decreased gluconeogenesis from lactate, but not from alanine. The inhibition of gluconeogenesis was associated with a stimulation of ketone-body production and an inhibition of pyruvate oxidation. These metabolic changes were suppressed in the presence of iodotubercidin (an inhibitor of adenosine kinase), but were reinforced in the presence of deoxycoformycin (an inhibitor of adenosine deaminase); 2-chloroadenosine induced no change in gluconeogenesis from lactate. These data indicate that the inhibition of gluconeogenesis by adenosine probably results from its conversion into adenine nucleotides. In the presence of lactate or pyruvate, but not with alanine or asparagine, this conversion resulted in a decrease in the [ATP]/[ADP] ratio in both mitochondrial and cytosolic compartments. Adenosine decreased the Pi concentration with all gluconeogenic substrates.


2002 ◽  
Vol 269 (15) ◽  
pp. 3742-3750 ◽  
Author(s):  
Ulrike Krause ◽  
Luc Bertrand ◽  
Liliane Maisin ◽  
Maria Rosa ◽  
Louis Hue

2003 ◽  
Vol 279 (9) ◽  
pp. 8452-8459 ◽  
Author(s):  
Takumi Kanazawa ◽  
Ikue Taneike ◽  
Ryuichiro Akaishi ◽  
Fumiaki Yoshizawa ◽  
Norihiko Furuya ◽  
...  

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