scholarly journals Correlation between muscle glycogen synthase activity and in vivo insulin action in man.

1984 ◽  
Vol 73 (4) ◽  
pp. 1185-1190 ◽  
Author(s):  
C Bogardus ◽  
S Lillioja ◽  
K Stone ◽  
D Mott
Keyword(s):  
Muscle Glycogen ◽  
Insulin Action ◽  
Glycogen Synthase ◽  
Glycogen Synthase Activity

Decreased insulin action in skeletal muscle from patients with McArdle's disease

2002 ◽  
Vol 282 (6) ◽  
pp. E1267-E1275 ◽  
Author(s):  
Jakob N. Nielsen ◽  
John Vissing ◽  
Jørgen F. P. Wojtaszewski ◽  
Ronald G. Haller ◽  
Najma Begum ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Tolerance ◽  
Muscle Glycogen ◽  
Insulin Action ◽  
Glycogen Synthase ◽  
Oral Glucose ◽  
Mcardle's Disease ◽  
Mcardle’S Disease ◽  
The Difference ◽  
Glycogen Synthase Activity

Insulin action is decreased by high muscle glycogen concentrations in skeletal muscle. Patients with McArdle's disease have chronic high muscle glycogen levels and might therefore be at risk of developing insulin resistance. In this study, six patients with McArdle's disease and six matched control subjects were subjected to an oral glucose tolerance test and a euglycemic-hyperinsulinemic clamp. The muscle glycogen concentration was 103 ± 45% higher in McArdle patients than in controls. Four of six McArdle patients, but none of the controls, had impaired glucose tolerance. The insulin-stimulated glucose utilization and the insulin-stimulated increase in glycogen synthase activity during the clamp were significantly lower in the patients than in controls (51.3 ± 6.0 vs. 72.6 ± 13.1 μmol · min−1 · kg lean body mass−1, P < 0.05, and 53 ± 15 vs. 79 ± 9%, P < 0.05, n = 6, respectively). The difference in insulin-stimulated glycogen synthase activity between the pairs was significantly correlated ( r = 0.96, P < 0.002) with the difference in muscle glycogen level. The insulin-stimulated increase in Akt phosphorylation was smaller in the McArdle patients than in controls (45 ± 13 vs. 76 ± 13%, P < 0.05, respectively), whereas basal and insulin-stimulated glycogen synthase kinase 3α and protein phosphatase-1 activities were similar in the two groups. Furthermore, the ability of insulin to decrease and increase fat and carbohydrate oxidation, respectively, was blunted in the patients. In conclusion, these data show that patients with McArdle's glycogen storage disease are insulin resistant in terms of glucose uptake, glycogen synthase activation, and alterations in fuel oxidation. The data further suggest that skeletal muscle glycogen levels play an important role in the regulation of insulin-stimulated glycogen synthase activity.

Insulin promotes glycogen synthesis in the absence of GSK3 phosphorylation in skeletal muscle

2008 ◽  
Vol 294 (1) ◽  
pp. E28-E35 ◽  
Author(s):  
Michale Bouskila ◽  
Michael F. Hirshman ◽  
Jørgen Jensen ◽  
Laurie J. Goodyear ◽  
Kei Sakamoto
Keyword(s):  
Skeletal Muscle ◽  
Glucose Uptake ◽  
Muscle Glycogen ◽  
Glycogen Content ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Wild Type ◽  
Muscle Glycogen Synthesis ◽  
Mutant Forms

Insulin promotes dephosphorylation and activation of glycogen synthase (GS) by inactivating glycogen synthase kinase (GSK) 3 through phosphorylation. Insulin also promotes glucose uptake and glucose 6-phosphate (G-6- P) production, which allosterically activates GS. The relative importance of these two regulatory mechanisms in the activation of GS in vivo is unknown. The aim of this study was to investigate if dephosphorylation of GS mediated via GSK3 is required for normal glycogen synthesis in skeletal muscle with insulin. We employed GSK3 knockin mice in which wild-type GSK3α and -β genes are replaced with mutant forms (GSK3α/βS21A/S21A/S9A/S9A), which are nonresponsive to insulin. Although insulin failed to promote dephosphorylation and activation of GS in GSK3α/βS21A/S21A/S9A/S9Amice, glycogen content in different muscles from these mice was similar compared with wild-type mice. Basal and epinephrine-stimulated activity of muscle glycogen phosphorylase was comparable between wild-type and GSK3 knockin mice. Incubation of isolated soleus muscle in Krebs buffer containing 5.5 mM glucose in the presence or absence of insulin revealed that the levels of G-6- P, the rate of [14C]glucose incorporation into glycogen, and an increase in total glycogen content were similar between wild-type and GSK3 knockin mice. Injection of glucose containing 2-deoxy-[3H]glucose and [14C]glucose also resulted in similar rates of muscle glucose uptake and glycogen synthesis in vivo between wild-type and GSK3 knockin mice. These results suggest that insulin-mediated inhibition of GSK3 is not a rate-limiting step in muscle glycogen synthesis in mice. This suggests that allosteric regulation of GS by G-6- P may play a key role in insulin-stimulated muscle glycogen synthesis in vivo.

Glucose transport rate and glycogen synthase activity both limit skeletal muscle glycogen accumulation

2002 ◽  
Vol 282 (6) ◽  
pp. E1214-E1221 ◽  
Author(s):  
Jonathan S. Fisher ◽  
Lorraine A. Nolte ◽  
Kentaro Kawanaka ◽  
Dong-Ho Han ◽  
Terry E. Jones ◽  
...  
Keyword(s):  
Glucose Transport ◽  
Muscle Glycogen ◽  
Glycogen Synthase ◽  
Transport Rate ◽  
Prolonged Incubation ◽  
Glycogen Accumulation ◽  
Gf 109203X ◽  
Rate Limiting ◽  
Glycogen Synthase Activity

We varied rates of glucose transport and glycogen synthase I (GS-I) activity (%GS-I) in isolated rat epitrochlearis muscle to examine the role of each process in determining the rate of glycogen accumulation. %GS-I was maintained at or above the fasting basal range during 3 h of incubation with 36 mM glucose and 60 μU/ml insulin. Lithium (2 mM LiCl) added to insulin increased glucose transport rate and muscle glycogen content compared with insulin alone. The glycogen synthase kinase-3β inhibitor GF-109203x (GF; 10 μM) maintained %GS-I about twofold higher than insulin with or without lithium but did not increase glycogen accumulation. When %GS-I was lowered below the fasting range by prolonged incubation with 36 mM glucose and 2 mU/ml insulin, raising rates of glucose transport with bpV(phen) or of %GS-I with GF produced additive increases in glycogen concentration. Phosphorylase activity was unaffected by GF or bpV(phen). In muscles of fed animals, %GS-I was ∼30% lower than in those of fasted rats, and insulin-stimulated glycogen accumulation did not occur unless %GS-I was raised with GF. We conclude that the rate of glucose transport is rate limiting for glycogen accumulation unless %GS-I is below the fasting range, in which case both glucose transport rate and GS activity can limit glycogen accumulation.

scholarly journals Effect of muscle glycogen depletion on in vivo insulin action in man.

1983 ◽  
Vol 72 (5) ◽  
pp. 1605-1610 ◽  
Author(s):  
C Bogardus ◽  
P Thuillez ◽  
E Ravussin ◽  
B Vasquez ◽  
M Narimiga ◽  
...  
Keyword(s):  
Muscle Glycogen ◽  
Insulin Action ◽  
Glycogen Depletion

scholarly journals Muscle glycogen synthase in vivo state:

FEBS Letters ◽  
1977 ◽  
Vol 80 (1) ◽  
pp. 95-98 ◽  
Author(s):  
P.J. Roach ◽  
M. Rosell-Perez ◽  
J. Larner
Keyword(s):  
Muscle Glycogen ◽  
Glycogen Synthase

Glycogen Metabolism in Psoriatic Epidermis and in Regenerating Epidermis

1984 ◽  
Vol 67 (3) ◽  
pp. 291-298 ◽  
Author(s):  
C. S. Harmon ◽  
P. J. R. Phizackerley
Keyword(s):  
Glycogen Content ◽  
Glycogen Synthase ◽  
Quantitative Estimation ◽  
Glycogen Synthesis ◽  
Pentose Phosphate ◽  
Normal Epithelium ◽  
Glycogen Synthase Activity ◽  
Psoriatic Lesions ◽  
Wound Epithelium

1. The observation that the glycogen content of epidermis from psoriatic lesions and from regenerating wound epithelium is increased has been confirmed by quantitative estimation. 2. In epidermis from psoriatic lesions, although the proportion of glycogen synthase in the I form is only about 5% of the total and similar to control values, total glycogen synthase activity is increased approximately 4-fold and hence glycogen synthase I activity is increased to the same extent. In contrast, total phosphorylase activity is only slightly increased and, since the proportion of the enzyme in the a form is reduced, phosphorylase a activity is similar to control values. 3. In epidermis from psoriatic lesions, the concentration of UDP-glucose is approximately doubled, and the concentrations of fructose 1,6-bisphosphate and of 6-phosphogluconate are increased approximately 5-fold. It is concluded that rates of glycogen synthesis, of glycolysis and of the pentose phosphate pathway are all enhanced in vivo and in consequence the rate of glucose uptake by psoriatic epidermis must be increased. 4. In the non-involved epidermis of psoriatic patients the glycogen content is within normal limits, and although total glycogen synthase activity is increased the ratio of glycogen synthase I to phosphorylase a is maintained at normal levels by the appropriate phosphorylation of both enzymes. 5. In regenerating wound epithelium in the pig, the changes in enzyme activity and in metabolite concentration closely resemble those found in epithelium from psoriatic lesions except that in wound epithelium the proportion of phosphorylase in the a form is increased relative to normal epithelium.

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