Effect of weaning on the activities of glycogen synthase and phosphorylase in rat liver

1985 ◽  
Vol 63 (2) ◽  
pp. 143-147
Author(s):  
Ramji L. Khandelwal ◽  
Ralph P. Braun ◽  
Joseph F. Angel
Keyword(s):  
Rat Liver ◽  
Activity Ratio ◽  
Glycogen Synthase ◽  
Active Form ◽  
Liver Glycogen ◽  
Suckling Period ◽  
Low Level

The effects of weaning on the level of glycogen and the activities of glycogen synthase and phosphorylase were determined in rat liver. Glycogen levels in rat liver increased at the start of the weaning period and reached a plateau on postnatal day 20. The active form of glycogen synthase increased until postnatal day 19 and then declined. Total glycogen synthase (active + inactive) remained high during the suckling period and declined to a new low level during the weaning period. The activity ratio (active/total) increased from day 16 to days 18 – 22 and then decreased to the same level as found during the suckling period. At the onset of weaning the active form of phosphorylase decreased, whereas total phosphorylase initially increased and then decreased after postnatal day 20. Both forms of phosphorylase increased again at the end of the weaning period. The activity ratio decreased at the start of weaning and remained low throughout the rest of the weaning period. The effects of premature weaning were similar to those observed in normally weaned animals, but the changes occurred sooner and were more pronounced.

scholarly journals Regulation of rat liver glycogen synthase. Roles of Ca2+, phosphorylase kinase, and phosphorylase a.

1983 ◽  
Vol 258 (9) ◽  
pp. 5490-5497
Author(s):  
W G Strickland ◽  
M Imazu ◽  
T D Chrisman ◽  
J H Exton
Keyword(s):  
Rat Liver ◽  
Glycogen Synthase ◽  
Liver Glycogen ◽  
Phosphorylase Kinase

Response of mouse liver glycogen cycle enzymes to endotoxin treatment

1976 ◽  
Vol 231 (4) ◽  
pp. 1285-1289 ◽  
Author(s):  
O Giger ◽  
RE McCallum
Keyword(s):  
Mouse Liver ◽  
Glycogen Phosphorylase ◽  
Glycogen Synthase ◽  
Lethal Dose ◽  
Active Form ◽  
Liver Glycogen ◽  
Phosphorylase Activity ◽  
Induced Changes ◽  
Glycogen Phosphorylase Activity ◽  
Glycogen Synthase Activity

The present study was undertaken to characterize endotoxin-induced changes in carbohydrate metabolism and more specifically, to determine the contribution of glycogenolysis to the loss of liver glycogen. Female ICR mice, fasted overnight, were injected with a median lethal dose (LD50, 9 mg/kg) of endotoxin extracted from Salmonella typhimurium strain SR-11. Glycogen synthase and glycogen phosphorylase activities were measured at 0.5 and 6 h after treatment. Endotoxin treatment did not alter total glycogen synthase activity, but the amount of enzyme present in the active form was significantly lower in endotoxic mice. There was no significant increase in glycogen phosphorylase activity in endotoxin-treated mice. Glycogen phosphorylase was activated to the same extent in control and endotoxic mice by decapitation or intravenous epinephrine (25 or 1 mug/kg). The results of this study indicate no significant increase in glycogen phosphorylase activity in endotoxic mice, contraindicating enhanced glycogenolysis as a mechanism for depletion of carbohydrate following endotoxin injection. Altered activation of glycogen synthase, however, may contribute to the loss of glycogen during endotoxemia.

Phosphorylation of rat liver glycogen synthase bound to the glycogen particle

1984 ◽  
Vol 235 (1) ◽  
pp. 186-195 ◽  
Author(s):  
Akira Akatsuka ◽  
Toolsee J. Singh ◽  
Kuo-Ping Huang
Keyword(s):  
Rat Liver ◽  
Glycogen Synthase ◽  
Liver Glycogen ◽  
Glycogen Particle

scholarly journals Hepatic Overexpression of a Constitutively Active Form of Liver Glycogen Synthase Improves Glucose Homeostasis

2010 ◽  
Vol 285 (48) ◽  
pp. 37170-37177 ◽  
Author(s):  
Susana Ros ◽  
Delia Zafra ◽  
Jordi Valles-Ortega ◽  
Mar García-Rocha ◽  
Stephen Forrow ◽  
...  
Keyword(s):  
Glucose Homeostasis ◽  
Glycogen Synthase ◽  
Active Form ◽  
Liver Glycogen ◽  
Constitutively Active

In vivo phosphorylation of liver glycogen synthase. Effect of glucose and glucagon treatment of liver cells on the distribution of the [32P] phosphate

1993 ◽  
Vol 71 (1-2) ◽  
pp. 90-96 ◽  
Author(s):  
Agnes W. H. Tan ◽  
Frank Q. Nuttall
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Rat Liver ◽  
Glycogen Synthase ◽  
Liver Glycogen ◽  
Liver Cells ◽  
Phosphorylation State ◽  
Glucose Treatment ◽  
Effect Of Glucose

Glycogen synthase was phosphorylated in vivo by perfusing rat liver or incubating liver cells with [32P]phosphate. It was then isolated by immunoprecipitation and subjected to exhaustive tryptic proteolysis. The trypsin-derived [32P]phosphopeptides were separated by high pressure liquid chromatography (HPLC). Incubation of in vivo phosphorylated synthase with endogenous synthase phosphatase to convert synthase D to synthase R resulted in removal of phosphate from all of the labeled phosphopeptides. In prelabeled liver cells treated with glucagon or glucose, the activities of synthase and phosphorylase changed in the direction expected. The total labeling in the immunoprecipitated synthase was found to be increased to 126% and decreased to 67% of the control with glucagon and glucose treatment, respectively. When the HPLC [32P]phosphopeptide profile of synthase from glucagon-treated animals was compared with that of controls, there were only minor differences in the two profiles. All the peaks were present and the proportion of labeling in each remained similar. There also was only a modest change in the [32P]phosphopeptide profile with glucose treatment when compared with that of controls. These results indicate that regulation of synthase activity in the hepatocyte involves changes in phosphorylation at multiple sites. Indeed, in 32P-labeled liver cells, all of the labeled sites appeared to be involved.Key words: glycogen synthase, liver, phosphorylation state, glucose treatment, glucagon treatment.

Kinetic analysis of glycogen synthase and PDC in cirrhotic rat liver and skeletal muscle

1994 ◽  
Vol 267 (6) ◽  
pp. E900-E906 ◽  
Author(s):  
M. G. Giardina ◽  
M. Matarazzo ◽  
L. Sacca
Keyword(s):  
Skeletal Muscle ◽  
Activity Ratio ◽  
Glycogen Synthase ◽  
Pyruvate Dehydrogenase Complex ◽  
Active Form ◽  
Maximal Velocity ◽  
Michaelis Constant ◽  
Allosteric Activation ◽  
Independent Form ◽  
And Control

Glycogen synthase (GS) and pyruvate dehydrogenase complex (PDC) were kinetically analyzed in the liver and skeletal muscle of fasted and refed rats with thioacetamide-induced cirrhosis of the liver. In control rats, refeeding induced a 54% decrease in the A0.5 for glucose 6-phosphate (G-6-P) of hepatic GS (P < 0.001), reflecting allosteric activation of the enzyme. In skeletal muscle the A0.5 for G-6-P did not change after refeeding, whereas the activity ratio increased by 56% (P < 0.01), indicating a greater percentage of the active G-6-P-independent form of the enzyme. In cirrhotic rats, neither the A0.5 for G-6-P of liver GS nor the activity ratio of muscle GS was influenced by refeeding. Consequently, glycogen replenishment was significantly impaired both in the liver (2.56 +/- 0.2 vs. 5.11 +/- 0.4 g/100 g; P < 0.001) and skeletal muscle (0.45 +/- 0.01 vs. 0.52 +/- 0.02 g/100 g; P < 0.01). Refeeding increased the percentage of the active form of hepatic PDC both in control (+88%; P < 0.01) and cirrhotic rats (+91%; P < 0.001). In the latter, however, the rates of total and active PDC were significantly lower than in controls [-44% and -40% in fasted (P < 0.005) and refed (P < 0.005) rats, respectively]. Muscle PDC kinetics (both maximal velocity and Michaelis constant) and the percent active form were identical in cirrhotic and control rats, regardless of the nutritional state.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of protein kinase C in the regulation of rat liver glycogen synthase

1987 ◽  
Vol 252 (1) ◽  
pp. 81-90 ◽  
Author(s):  
Hiroki Nakabayashi ◽  
Kai-Foon Jesse Chan ◽  
Kuo-Ping Huang
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Rat Liver ◽  
Glycogen Synthase ◽  
Liver Glycogen ◽  
Kinase C
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