Regulation of glycogenolysis in human muscle at rest and during exercise

1982 ◽  
Vol 53 (3) ◽  
pp. 708-715 ◽  
Author(s):  
D. Chasiotis ◽  
K. Sahlin ◽  
E. Hultman
Keyword(s):  
Glycogen Phosphorylase ◽  
Total Activity ◽  
Human Muscle ◽  
Phosphorylase Activity ◽  
Michaelis Constant ◽  
Bicycle Exercise ◽  
Muscle Phosphorylase ◽  
Glycogen Utilization ◽  
Main Factors

The regulation of glycogenolysis in human muscle during isometric and dynamic exercise has been investigated. Total glycogen phosphorylase and synthase activities were unchanged during exercise. The fraction of phosphorylase in the alpha form at rest was estimated to be 20%, but the data indicate that the in vivo activity was low and critically dependent on the concentration of inorganic phosphate (Pi) in the muscle. Phosphorylase alpha increased initially 2.4-fold during isometric contraction and 1.6-fold during maximal bicycle exercise but reverted to or below the resting value at fatigue/exhaustion. At rest synthase I was 1713;48% of the total activity but decreased during exercise to about half of this value. The reciprocal changes in phosphorylase and synthase correlate with the enhanced rate of glycogenolysis during exercise. Michaelis constant (Km) for Pi was 27 mmol . l-1 for phosphorylase alpha and 7 mmol . l-1 for alpha + b. From consideration of the changes in Pi during exercise (to 20–30 mmol . l–1) it was concluded that Pi is one of the main factors determining phosphorylase activity and provides a link between phosphocreatine breakdown and glycogen utilization in muscle.

Glycogen phosphorylase in fish muscle: demonstration of three interconvertible forms

1990 ◽  
Vol 258 (2) ◽  
pp. C344-C351 ◽  
Author(s):  
H. Schmidt ◽  
G. Wegener
Keyword(s):  
Glycogen Phosphorylase ◽  
Specific Activity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Muscular Activity ◽  
Fish Muscle ◽  
Kinetic Properties ◽  
Phosphorylase Activity ◽  
Tissue Extracts

White skeletal muscle of crucian carp contains a single isoenzyme of glycogen phosphorylase, which was purified approximately 300-fold to a specific activity of approximately 13 mumol.min-1.mg protein-1 (assayed in the direction of glycogen breakdown at 25 degrees C). Tissue extracts of crucian muscle produced three distinct peaks of phosphorylase activity when separated on DEAE-Sephacel. Peaks 1 and 3 were identified, in terms of kinetic properties and by interconversion experiments, as phosphorylase b and a, respectively. Peak 2 was shown to be a phospho-dephospho hybrid. The three interconvertible forms of phosphorylase were purified and shown to be dimeric molecules at 20 degrees C. At 5 degrees C, a and the hybrid tended to form tetramers. The Mr of the subunit was estimated to be 96,400 from sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The hybrid is kinetically homogeneous, and its kinetic properties are intermediate between those of b and a forms. The b, hybrid, and a forms of phosphorylase can be isolated from rapidly frozen muscle of crucian but in different proportions, depending on whether fish were anesthetized or forced to muscular activity for 20 s. Muscle of anesthetized crucian had 36, 36, and 28% of phosphorylase b, hybrid, and a forms, respectively, whereas the corresponding values for exercised fish were 12, 37, and 51%. Results suggest that three interconvertible forms of phosphorylase exist simultaneously in crucian muscle and that hybrid phosphorylase is active in contracting muscle in vivo.

scholarly journals Adenovirus-mediated delivery into myocytes of muscle glycogen phosphorylase, the enzyme deficient in patients with glycogen-storage disease type V

1994 ◽  
Vol 304 (3) ◽  
pp. 1009-1014 ◽  
Author(s):  
S Baqué ◽  
C B Newgard ◽  
R D Gerard ◽  
J J Guinovart ◽  
A M Gómez-Foix
Keyword(s):  
Muscle Glycogen ◽  
Glycogen Phosphorylase ◽  
Recombinant Adenovirus ◽  
Genetic Diseases ◽  
C2c12 Myoblast ◽  
Mrna Levels ◽  
Phosphorylase Activity ◽  
Muscle Phosphorylase ◽  
The Impact

The feasibility of using adenovirus as a vector for the introduction of glycogen phosphorylase activity into myocytes has been examined. We used the C2C12 myoblast cell line to assay the impact of phosphorylase gene transfer on myocyte glycogen metabolism and to reproduce in vitro the two strategies proposed for the treatment of muscle genetic diseases, myoblast transplantation and direct DNA delivery. In this study, a recombinant adenovirus containing the muscle glycogen phosphorylase cDNA transcribed from the cytomegalovirus promoter (AdCMV-MGP) was used to transduce both differentiating myoblasts and nondividing mature myotube cells. Muscle glycogen phosphorylase mRNA levels and total phosphorylase activity were increased in both cell types after viral treatment although more efficiently in the differentiated myotubes. The increase in phosphorylase activity was transient (15 days) in myoblasts whereas in myotubes higher levels of phosphorylase gene expression and activity were reached, which remained above control levels for the duration of the study (20 days). The introduction of muscle phosphorylase into myotubes enhanced their glycogenolytic capacity. AdCMV MGP-transduced myotubes had lower glycogen levels under basal conditions. In addition, these engineered cells showed more extensive glycogenolysis in response to both adrenaline, which stimulates glycogen phosphorylase phosphorylation, and carbonyl cyanide m-chlorophenylhydrazone, a metabolic uncoupler. In conclusion, transfer of the muscle glycogen phosphorylase cDNA into myotubes confers an enhanced and regulatable glycogenolytic capacity. Thus this system might be useful for delivery of muscle glycogen phosphorylase and restoration of glycogenolysis in muscle cells from patients with muscle phosphorylase deficiency (McArdle's disease).

Regulation of glycogenolysis in human muscle in response to epinephrine infusion

1983 ◽  
Vol 54 (1) ◽  
pp. 45-50 ◽  
Author(s):  
D. Chasiotis ◽  
K. Sahlin ◽  
E. Hultman
Keyword(s):  
Active Site ◽  
Inorganic Phosphate ◽  
Glycogen Phosphorylase ◽  
Glycogen Content ◽  
Glycogen Synthase ◽  
Human Muscle ◽  
Prolonged Infusion ◽  
Epinephrine Infusion ◽  
Resting Muscle

The regulation of glycogenolysis in human muscle during epinephrine infusion has been investigated. The content of cAMP in resting muscle was 2.7 +/- 0.7 (SD) mumol . kg dry muscle-1 and increased threefold during the first 5 min of infusion. Total glycogen phosphorylase and glycogen synthase activities were unchanged during the infusion. The proportion of phosphorylase in the a form in the basal state was estimated to be at least 22.5% and during infusion 80–90%. During infusion, synthase I activity decreased. The muscle glycogen content was 340 mmol . kg dry wt-1 and decreased during the first 2 min of infusion at a rate of 11.0 mmol glycosyl units . kg dry wt-1 . min-1. Prolonged infusion resulted in a much lower glycogenolytic rate, even though most of the phosphorylase was still in the a form. Accumulation of hexose monophosphates and lactate followed the changes in glycogen. It was concluded that despite the almost total transformation of phosphorylase to the a form, the in vivo activity was maintained at a low level. It is suggested that this may be due to a low concentration of inorganic phosphate at the active site of the enzyme.

Investigation of human and rat inactive renin in plasma and kidney

1991 ◽  
Vol 69 (9) ◽  
pp. 1341-1349 ◽  
Author(s):  
A. Jindra Jr. ◽  
J. Bultas ◽  
J. Ort ◽  
R. Kvetnansky
Keyword(s):  
Immobilization Stress ◽  
Rat Kidney ◽  
Total Activity ◽  
Renin Secretion ◽  
Renal Veins ◽  
Bicycle Exercise ◽  
Initial Interval ◽  
Active Renin ◽  
Inactive Renin

Under an initial interval of immobilization stress in rats, reciprocal changes of plasma active and inactive renin were observed, suggesting activation of circulating inactive renin. Molecular weight (MW) studies revealed that this activation might proceed via a MW shift from inactive renin with MW of 50 000 to active renin of MW 43 000. In a later interval of stress, under stimulated renin secretion, a lower MW form (38 000) of active renin was released into the circulation. This MW is close to that of active renin (39 000) found in rat kidney renin granules. In renin granules, equilibrated in fractions of 1.6 and 1.7 mol/L sucrose in discontinuous density gradient, trypsin-activatable renin activity formed 36 and 16% of total activity, respectively. In humans, under acute bicycle exercise, a lower MW form (39 000) of active renin was released into the circulation, while the content of inactive renin with MW in the range of 51 000–58 000 and at 47 000 did not substantially change. There was a slight decrease in circulating inactive renin passing through the kidney. The data suggest that, at least in rats, in vivo pathways for activation of inactive renin might exist, other than that proceeding before secretion from renin granules. Under the conditions of increased renin secretion, a lower MW form of active renin is mainly released into the circulation in both rats and humans.Key words: active renin, inactive renin, renal veins, renin granules, stress.

Fish muscle glycogen phosphorylase

1968 ◽  
Vol 46 (5) ◽  
pp. 423-432 ◽  
Author(s):  
M. Yamamoto
Keyword(s):  
Skeletal Muscle ◽  
Glycogen Phosphorylase ◽  
Active Form ◽  
Maximal Activity ◽  
Fish Muscle ◽  
Salmo Gairdneri ◽  
Rabbit Muscle ◽  
Muscle Phosphorylase

Glycogen phosphorylase b was purified 70- to 90-fold from skeletal muscle of rainbow trout (Salmo gairdneri). The purified enzyme exhibited maximal activity near pH 6.8 at 37°. Of several 5′-nucleotides tested, only 5′-AMP caused stimulation of phosphorylase b. The Km value for glucose-1-phosphate was 10–15 mM, and for 5′-AMP, 0.2–0.4 mM. Glucose (25 mM) and ATP (5 mM) were both inhibitory, but glucose-6-phosphate (5 mM) had no effect. Inactive trout muscle phosphorylase was converted to the active form in vivo by subjecting a fish to physical exercise. The conversion of fish muscle phosphorylase b to a was also catalyzed in vitro with purified rabbit muscle phosphorylase b kinase in the presence of ATP and Mg++. Evidence is presented to indicate the presence of phosphorylase b kinase and phosphorylase phosphatase in trout skeletal muscle.

scholarly journals The effects of calcium ions, ionophore A23187 and inhibition of energy metabolism on protein degradation in the rat diaphragm and epitrochlearis muscles in vitro

1980 ◽  
Vol 190 (3) ◽  
pp. 593-603 ◽  
Author(s):  
P H Sugden
Keyword(s):  
Energy Metabolism ◽  
Protein Degradation ◽  
Glycogen Phosphorylase ◽  
Activity Ratio ◽  
Ionophore A23187 ◽  
Rat Diaphragm ◽  
Phosphorylase Activity ◽  
Glycogen Phosphorylase Activity

1. The effects of external Ca2+, EGTA, ionophore A23187, CN-, dinitrophenol and iodoacetamide on the rate of protein degradation in the rat diaphragm and epitrochlearis muscles in vitro were investigated. 2. External Ca2+ increased protein degradation when compared with external EGTA. Protein degradation was further increased by Ca2+ + ionophore A23187. 3. EGTA and ionophore A23187 decreased ATP and phosphocreatine concentrations and the ATP/ADP ratio. 4. CN-, dinitrophenol and iodoacetamide decreased protein degradation, presumably by interfering with energy metabolism. 5. The effects of EGTA may be caused by disturbances in energy metabolism. The effects of ionophore A23187 cannot be readily explained by disturbances in energy metabolism. 6. Incubation of diaphragms with Ca2+ causes a rapid increase in whole-tissue Ca content. This is further stimulated by ionophore A23187. The uptake of Ca2+ may be, at least in part, into the cytoplasm because an increase in the glycogen phosphorylase activity ratio is observed. 7. A Ca2+-activated proteinase is present in rat heart and diaphragm. This enzyme may mediate in part the effects of Ca2+ described above. The apparent KA of this enzyme for Ca2+ is about 0.25 mM. 8. Because effects of ionophore A23187 cause a large increase in whole-tissue Ca content and because the Ca2+-activated proteinase has a relatively low affinity for Ca2+, it is felt that the effects of Ca2+ upon muscle proteolysis are unlikely to be of importance in steady-state protein turnover in vivo. The mechanism may, however, be important in breakdown of necrotic tissue in the living animal.

scholarly journals Expression of muscle-gene-specific isozymes of phosphorylase and creatine kinase in innervated cultured human muscle.

1986 ◽  
Vol 103 (4) ◽  
pp. 1423-1429 ◽  
Author(s):  
A Martinuzzi ◽  
V Askanas ◽  
T Kobayashi ◽  
W K Engel ◽  
S Di Mauro
Keyword(s):  
Spinal Cord ◽  
Creatine Kinase ◽  
Glycogen Phosphorylase ◽  
De Novo ◽  
Muscle Fibers ◽  
Total Activity ◽  
Human Muscle ◽  
Rat Embryo ◽  
Muscle Gene ◽  
Large Groups

Isozymes of creatine kinase and glycogen phosphorylase are excellent markers of skeletal muscle maturation. In adult innervated muscle only the muscle-gene-specific isozymes are present, whereas aneurally cultured human muscle has predominantly the fetal pattern of isozymes. We have studied the isozyme pattern of human muscle cultured in monolayer and innervated by rat embryo spinal cord explants for 20-42 d. In this culture system, large groups of innervated muscle fibers close to the ventral part of the spinal cord explant continuously contracted. The contractions were reversibly blocked by 1 mM d-tubocurarine. In those innervated fibers, the total activity and the muscle-gene-specific isozymes of both enzymes increased significantly. The amount of muscle-gene-specific isozymes directly correlated with the duration of innervation. Control noninnervated muscle fibers from the same dishes as the innervated fibers remained biochemically immature. This study demonstrated that de novo innervation of human muscle cultured in monolayer exerts a time-related maturational influence that is not mediated by a diffusable neural factor.

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 Unsaturated fatty acids activate glycogen phosphorylase in cultured rat hepatocytes

1991 ◽  
Vol 276 (1) ◽  
pp. 209-215 ◽  
Author(s):  
A Gomez-Muñoz ◽  
P Hales ◽  
D N Brindley
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Glycogen Phosphorylase ◽  
Unsaturated Fatty Acids ◽  
High Fatty Acid ◽  
Rat Hepatocytes ◽  
Phosphorylase Activity ◽  
Cultured Rat Hepatocytes ◽  
Glycogen Phosphorylase Activity

Oleate, linoleate, linolenate, arachidonate and eicosapentaenoate, but not myristate, palmitate and stearate, stimulated glycogen phosphorylase activity by 2-8-fold when added to cultured rat hepatocytes. Addition of BSA or Ca2- to the incubation medium decreased the stimulating effects of the unsaturated fatty acids. The combination of oleate or linolenate, with corticosterone, testosterone or estradiol produced synergistic stimulations of phosphorylase activity. The stimulation of glycogen phosphorylase activity by linolenate was inhibited by staurosporine or sphingosine. Staurosporine (80 nM) alone also decreased basal phosphorylase activities by about 60%. The results show that unsaturated fatty acids can be used as model agonists to stimulate phosphorylase activity by a mechanism that probably involves protein kinase C. On the basis of the fatty acid: BSA ratios used, this stimulation should only occur in vivo at high fatty acid concentrations when accompanied by hypoalbuminaemia.

Sign in / Sign up

Export Citation Format

Share Document