scholarly journals Regulation of glycogen synthase and phosphorylase during recovery from high-intensity exercise in the rat

1997 ◽  
Vol 322 (1) ◽  
pp. 303-308 ◽  
Author(s):  
Lambert BRÄU ◽  
Luis D. M. C. B. FERREIRA ◽  
Sasha NIKOLOVSKI ◽  
Ghazala RAJA ◽  
T. Norman PALMER ◽  
...  
Keyword(s):  
Soleus Muscle ◽  
High Intensity ◽  
Glycogen Phosphorylase ◽  
Glycogen Synthase ◽  
High Intensity Exercise ◽  
Phosphorylation State ◽  
Activity Ratios ◽  
Glycogen Repletion ◽  
Glycogen Deposition ◽  
Gastrocnemius Muscles

The aim of this study was to determine the role of the phosphorylation state of glycogen synthase and glycogen phosphorylase in the regulation of muscle glycogen repletion in fasted animals recovering from high-intensity exercise. Groups of rats were swum to exhaustion and allowed to recover for up to 120 min without access to food. Swimming to exhaustion caused substantial glycogen breakdown and lactate accumulation in the red, white and mixed gastrocnemius muscles, whereas the glycogen content in the soleus muscle remained stable. During the first 40 min of recovery, significant repletion of glycogen occurred in all muscles examined except the soleus muscle. At the onset of recovery, the activity ratios and fractional velocities of glycogen synthase in the red, white and mixed gastrocnemius muscles were higher than basal, but returned to pre-exercise levels within 20 min after exercise. In contrast, after exercise the activity ratios of glycogen phosphorylase in the same muscles were lower than basal, and increased to pre-exercise levels within 20 min. This pattern of changes in glycogen synthase and phosphorylase activities, never reported before, suggests that the integrated regulation of the phosphorylation state of both glycogen synthase and phosphorylase might be involved in the control of glycogen deposition after high-intensity exercise.

Effect of streptozotocin-induced diabetes on glycogen resynthesis in fasted rats post-high-intensity exercise

2001 ◽  
Vol 280 (1) ◽  
pp. E83-E91 ◽  
Author(s):  
Luis D. M. C.-B. Ferreira ◽  
Lambert Bräu ◽  
Sasha Nikolovski ◽  
Ghazala Raja ◽  
T. Norman Palmer ◽  
...  
Keyword(s):  
Food Intake ◽  
Body Mass ◽  
High Intensity ◽  
Glycogen Synthase ◽  
Diabetic Rats ◽  
High Intensity Exercise ◽  
Hepatic Glycogen ◽  
Mild Diabetes ◽  
Streptozotocin Induced Diabetes ◽  
Glycogen Repletion

It has recently been shown that food intake is not essential for the resynthesis of the stores of muscle glycogen in fasted animals recovering from high-intensity exercise. Because the effect of diabetes on this process has never been examined before, we undertook to explore this issue. To this end, groups of rats were treated with streptozotocin (60 mg/kg body mass ip) to induce mild diabetes. After 11 days, each animal was fasted for 24 h before swimming with a lead weight equivalent to 9% body mass attached to the tail. After exercise, the rate and the extent of glycogen repletion in muscles were not affected by diabetes, irrespective of muscle fiber composition. Consistent with these findings, the effect of exercise on the phosphorylation state of glycogen synthase in muscles was only minimally affected by diabetes. In contrast to its effects on nondiabetic animals, exercise in fasted diabetic rats was accompanied by a marked fall in hepatic glycogen levels, which, surprisingly, increased to preexercise levels during recovery despite the absence of food intake.

Particulate glycogen of mammalian liver: specificity in binding phosphorylase and glycogen synthase

1992 ◽  
Vol 70 (7) ◽  
pp. 523-527 ◽  
Author(s):  
Alexander Vardanis
Keyword(s):  
Molecular Weight ◽  
High Performance ◽  
Glycogen Phosphorylase ◽  
Hydrophobic Interactions ◽  
Glycogen Synthase ◽  
Early Period ◽  
Glycogen Particle ◽  
Molecular Weights ◽  
Glycogen Deposition ◽  
A Minor

The glycogen particle – glycogen metabolizing enzyme complex was investigated to gain some understanding of its physiological significance. Fractionations of populations of particles from mouse liver were carried out utilising open column and high performance liquid chromatography, and based either on the molecular weight of the particles or the hydrophobic interactions of the glycogen-associated proteins. The activities of glycogen phosphorylase and glycogen synthase were measured in these fractions. Fractionations were of tissue in different stages of glycogen deposition or mobilization. In animals fed ad libitum, glycogen synthase was associated with the whole spectrum of molecular weights, while the glycogen phosphorylase distribution was skewed in favour of the lower molecular weight species. Under conditions of glycogen mobilization, the phosphorylase distribution changed to include all molecular weights. The hydrophobic interaction separations demonstrated that glycogen synthase binds to a specific subpopulation of particles that is a minor proportion of the total. In general, there was a direct relationship of the total amount of phosphorylase and synthase bound during periods of mobilization and deposition, respectively. Two notable exceptions were the large amounts of glucose-6-P dependent synthase present during the early period of glycogen mobilization and the high amounts of active phosphorylase appearing shortly after food withdrawal, in spite of interim glycogen deposition from presumably already ingested food.Key words: glycogen particle, glycogenolysis, glycogenesis, glycogen phosphorylase, glycogen synthase.

scholarly journals Re-feeding after starvation involves a temporal shift in the control site of glycogen synthesis in rat muscle

1998 ◽  
Vol 329 (2) ◽  
pp. 341-347 ◽  
Author(s):  
P. Anthony JAMES ◽  
B. Carrie FLYNN ◽  
L. Sioned JONES ◽  
T. Norman PALMER ◽  
A. Paul FOURNIER
Keyword(s):  
Skeletal Muscles ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Quadriceps Muscle ◽  
Control Site ◽  
Temporal Shift ◽  
Fed State ◽  
Phosphorylation State ◽  
Glycogen Deposition ◽  
Later Phase

The starved-to-fed transition is accompanied by rapid glycogen deposition in skeletal muscles. On the basis of recent findings [Bräu, Ferreira, Nikolovski, Raja, Palmer and Fournier (1997) Biochem. J. 322, 303-308] that during recovery from exercise there is a shift from a glucose 6-phosphate/phosphorylation-based control of glycogen synthesis to a phosphorylation-based control alone, this paper seeks to establish whether a similar shift occurs in muscle during re-feeding after starvation in the rat. Chow re-feeding after 48 h of starvation resulted in glycogen deposition in all muscles examined (white, red and mixed quadriceps, soleus and diaphragm) to levels higher than those in the fed state. Although the early phase of re-feeding was associated with increases in glucose 6-phosphate levels in all muscles, there was no accompanying increase in the fractional velocity of glycogen synthase except in the white quadriceps muscle. This finding, together with the observation that the fractional velocity of glycogen synthase in most muscles was already high in the starved state, suggests that in the initial phase of glycogen deposition the phosphorylation state of the enzyme may be adequate to support net glycogen synthesis. In the later phase of re-feeding, the progressive decrease in the fractional velocity of glycogen synthase in association with a decrease in the rate of glycogen deposition suggests that glycogen synthesis is controlled primarily by changes in the phosphorylation state of glycogen synthase. In conclusion, this study suggests that there is a temporal shift in the site of control of glycogen synthesis as glycogen deposition progresses during re-feeding after starvation.

Effect of adrenodemedullation on metabolic responses to high-intensity exercise

1986 ◽  
Vol 251 (3) ◽  
pp. R552-R559
Author(s):  
J. C. Marker ◽  
D. A. Arnall ◽  
R. K. Conlee ◽  
W. W. Winder
Keyword(s):  
Soleus Muscle ◽  
High Intensity ◽  
Liver Glycogen ◽  
High Intensity Exercise ◽  
Metabolic Responses ◽  
Intense Exercise ◽  
Pentobarbital Sodium ◽  
Exercise Induced ◽  
Liver Glycogenolysis

To determine the role of epinephrine in glycogenolysis during high-intensity exercise, rats were adrenodemedullated (ADM) or sham operated (SHAM) and run for either 30 min at 38 m/min or for 5 min at 27, 38, or 48 m/min up a 15% grade. At the end of exercise the rats were anesthetized by intravenous injection of pentobarbital sodium. Liver, blood, and muscle samples were obtained. Plasma epinephrine values were 5.9 and 0.3 nM for SHAM and ADM animals, respectively, after 30 min of exercise. Liver glycogen decreased by 16 and 21 mg/g in the SHAM and ADM groups, respectively, and liver cAMP increased significantly in both groups. Glycogen in the soleus muscle decreased 80% in the SHAM but only 43% in the ADM animals after 30 min of exercise. The exercise-induced hyperglycemia observed in the SHAM animals was not present in the ADM animals. The responses of cyclic AMP, soleus glycogen, and blood glucose were similar in both the 5- and 30-min exercise groups. During intense exercise, epinephrine is unessential for stimulating liver glycogenolysis but does play an important role in stimulating glycogenolysis in the soleus muscle and in establishing exercise-induced hyperglycemia.

Insulin resistance in older rats

1984 ◽  
Vol 246 (5) ◽  
pp. E397-E404 ◽  
Author(s):  
M. Narimiya ◽  
S. Azhar ◽  
C. B. Dolkas ◽  
C. E. Mondon ◽  
C. Sims ◽  
...  
Keyword(s):  
Steady State ◽  
Glucose Uptake ◽  
Soleus Muscle ◽  
Insulin Action ◽  
Glycogen Phosphorylase ◽  
Glycogen Synthase ◽  
Insulin Levels ◽  
Old Rats ◽  
State Plasma

Insulin-stimulated glucose utilization was estimated in vivo in 1.5-, 4-, and 12-mo-old rats with an insulin suppression test wherein the height of the steady-state plasma glucose ( SSPG ) concentration, at similar steady-state plasma insulin levels, provides a direct reflection of the efficiency of insulin-stimulated glucose disposal. In parallel studies, the effect of age on in vitro insulin-stimulated glucose uptake was assessed in perfused hindlimb preparations. In addition, changes in the activity of enzymes that regulate muscle glycolysis, glycogenesis, and glycogenolysis were determined in isolated soleus muscle. The results indicated that rats got heavier as they became older, and changes in weight were associated with parallel increases in mean (+/- SE) SSPG concentrations as rats grew from 1.5 (56 +/- 3 mg/dl) to 4 (172 +/- 6 mg/dl) to 12 mo of age (194 +/- 8 mg/dl). The age-related decline in in vivo insulin action was associated with a reduction in insulin action on muscle, and maximal insulin-stimulated glucose uptake by perfused hindlimbs of 12-mo-old rats was approximately 50% of the value seen with perfused hindlimbs from 1.5-mo-old rats. Soleus muscle enzyme activity also varied with age, with significant increases in glycogen synthase and decreases in glycogen phosphorylase documented. Furthermore, muscle glycogen phosphorylase activity, which fell during an insulin infusion in 1.5-mo-old rats, did not change when 12-mo-old rats were infused at comparable insulin levels. Finally, glycogen content was significantly increased (P less than 0.01) in soleus muscle from 12-mo-old rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Fatty acid and amino acid modulation of glucose cycling in isolated rat hepatocytes

2001 ◽  
Vol 358 (3) ◽  
pp. 665-671 ◽  
Author(s):  
Lori A. GUSTAFSON ◽  
Mies NEEFT ◽  
Dirk-Jan REIJNGOUD ◽  
Folkert KUIPERS ◽  
Hans P. SAUERWEIN ◽  
...  
Keyword(s):  
Amino Acids ◽  
Glycogen Phosphorylase ◽  
Glycogen Synthase ◽  
Lactate Production ◽  
Rat Hepatocytes ◽  
Glycolytic Flux ◽  
Isolated Rat Hepatocytes ◽  
Glycogen Accumulation ◽  
Glycogen Deposition ◽  
Intracellular Glucose

We studied the influence of glucose/glucose 6-phosphate cycling on glycogen deposition from glucose in fasted-rat hepatocytes using S4048 and CP320626, specific inhibitors of glucose-6-phosphate translocase and glycogen phosphorylase respectively. The effect of amino acids and oleate was also examined. The following observations were made: (1) with glucose alone, net glycogen production was low. Inhibition of glucose-6-phosphate translocase increased intracellular glucose 6-phosphate (3-fold), glycogen accumulation (5-fold) without change in active (dephosphorylated) glycogen synthase (GSa) activity, and lactate production (4-fold). With both glucose 6-phosphate translocase and glycogen phosphorylase inhibited, glycogen deposition increased 8-fold and approached reported in vivo rates of glycogen deposition during the fasted → fed transition. Addition of a physiological mixture of amino acids in the presence of glucose increased glycogen accumulation (4-fold) through activation of GS and inhibition of glucose-6-phosphatase flux. Addition of oleate with glucose present decreased glycolytic flux and increased the flux through glucose 6-phosphatase with no change in glycogen deposition. With glucose 6-phosphate translocase inhibited by S4048, oleate increased intracellular glucose 6-phosphate (3-fold) and net glycogen production (1.5-fold), without a major change in GSa activity. It is concluded that glucose cycling in hepatocytes prevents the net accumulation of glycogen from glucose. Amino acids activate GS and inhibit flux through glucose-6-phosphatase, while oleate inhibits glycolysis and stimulates glucose-6-phosphatase flux. Variation in glucose 6-phosphate does not always result in activity changes of GSa. Activation of glucose 6-phosphatase flux by fatty acids may contribute to the increased hepatic glucose production as seen in Type 2 diabetes.

Glycogen supercompensation in rat soleus muscle during recovery from nonweight bearing

1989 ◽  
Vol 66 (6) ◽  
pp. 2782-2787 ◽  
Author(s):  
E. J. Henriksen ◽  
C. R. Kirby ◽  
M. E. Tischler
Keyword(s):  
Soleus Muscle ◽  
Enzyme Activities ◽  
Glycogen Phosphorylase ◽  
Time Course ◽  
Glycogen Synthase ◽  
Hindlimb Suspension ◽  
Phosphorylase Activity ◽  
Rat Soleus Muscle ◽  
Made In

The time course of glycogen changes in soleus muscle recovering from 3 days of nonweight bearing by hindlimb suspension was investigated. Within 15 min and up to 2 h, muscle glycogen decreased. Coincidentally, muscle glucose 6-phosphate and the fractional activity of glycogen phosphorylase, measured at the fresh muscle concentrations of AMP, increased. Increased fractional activity of glycogen synthase during this time was likely the result of greater glucose 6-phosphate and decreased glycogen. From 2 to 4 h, when the synthase activity remained elevated and the phosphorylase activity declined, glycogen levels increased (glycogen supercompensation). A further increase of glycogen up to 24 h did not correlate with the enzyme activities. Between 24 and 72 h, glycogen decreased to control values, possibly initiated by high phosphorylase activity at 24 h. At 12 and 24 h, the inverse relationship between glycogen concentration and the synthase activity ratio was lost, indicating that reloading transiently uncoupled glycogen control of this enzyme. These data suggest that the activities of glycogen synthase and phosphorylase, when measured at physiological effector levels, likely provide the closest approximation to the actual enzyme activities in vivo. Measurements made in this way effectively explained the majority of the changes in the soleus glycogen content during recovery from nonweight bearing.

scholarly journals Diverse effects of two allosteric inhibitors on the phosphorylation state of glycogen phosphorylase in hepatocytes

2002 ◽  
Vol 368 (1) ◽  
pp. 309-316 ◽  
Author(s):  
Theodore LATSIS ◽  
Birgitte ANDERSEN ◽  
Loranne AGIUS
Keyword(s):  
Glycogen Phosphorylase ◽  
Potent Inhibitor ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Glycogen Metabolism ◽  
Small Degree ◽  
Allosteric Inhibitors ◽  
Phosphorylation State ◽  
Stimulation Of

Two distinct allosteric inhibitors of glycogen phosphorylase, 1,4-dideoxy-1,4-imino-d-arabinitol (DAB) and CP-91149 (an indole-2-carboxamide), were investigated for their effects on the phosphorylation state of the enzyme in hepatocytes in vitro. CP-91149 induced inactivation (dephosphorylation) of phosphorylase in the absence of hormones and partially counteracted the phosphorylation caused by glucagon. Inhibition of glycogenolysis by CP-91149 can be explained by dephosphorylation of phosphorylase a. This was associated with activation of glycogen synthase and stimulation of glycogen synthesis. DAB, in contrast, induced a small degree of phosphorylation of phosphorylase. This was associated with inactivation of glycogen synthase and inhibition of glycogen synthesis. Despite causing phosphorylation (activation) of phosphorylase, DAB is a very potent inhibitor of glycogenolysis in both the absence and presence of glucagon. This is explained by allosteric inhibition of phosphorylase a, which overrides the increase in activation state. In conclusion, two potent phosphorylase inhibitors exert different effects on glycogen metabolism in intact hepatocytes as a result of opposite effects on the phosphorylation state of both phosphorylase and glycogen synthase.

Effects of insulin on carbohydrate and protein metabolism in voluntary running rats

1990 ◽  
Vol 259 (5) ◽  
pp. E706-E714 ◽  
Author(s):  
K. J. Rodnick ◽  
G. M. Reaven ◽  
S. Azhar ◽  
M. N. Goodman ◽  
C. E. Mondon
Keyword(s):  
Exercise Training ◽  
Soleus Muscle ◽  
Protein Metabolism ◽  
Glycogen Synthase ◽  
Dietary Control ◽  
Plantaris Muscle ◽  
Insulin Effect ◽  
Running Activity ◽  
Voluntary Running ◽  
Glycogen Deposition

The goal of this study was to assess the effects of voluntary running activity in rats on various aspects of carbohydrate and protein metabolism. After 6 wk of exercise training, rats (ET) were rested for 24 h and their hindquarters, along with those from sedentary control (SC) and dietary control (DC) rats, were perfused with 0, 60, 250, or 6,000 microU/ml insulin. At 0 insulin, glucose clearance was similar for all groups, and it was increased with added insulin. However, the insulin effect was 20–40% greater for ET rats at all insulin concentrations (P less than 0.05). Muscle glycogen deposition also increased with added insulin but showed muscle-specific differences. Specifically, glycogen content of the plantaris muscle was significantly higher in ET compared with SC or DC rats, whereas this pattern was reversed in soleus muscle. In plantaris muscle, insulin stimulated glucose 6-phosphate (G-6-P)-independent (-G-6-P) glycogen synthase activity only in SC and DC rats and increased its affinity for G-6-P at 250 microU/ml in all groups. In contrast, the -G-6-P synthase activity was not increased in soleus muscle and was actually decreased in all groups at 6,000 microU/ml. Tyrosine release was suppressed by insulin in all groups, but this effect was significantly greater at insulin levels of 60 microU/ml (P less than 0.02) in hindquarters from ET rats compared with SC and DC rats. Neither insulin nor exercise training decreased 3-methylhistidine release from perfused hindquarters.(ABSTRACT TRUNCATED AT 250 WORDS)

Sign in / Sign up

Export Citation Format

Share Document