Glycogen: A metabolic viewpoint

Geddes, Robert

doi:10.1007/bf01116132

Cited by 56 publications

(35 citation statements)

References 73 publications

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“…Differences in peak tetanic tension and specific force may result, at least in part, from the sevenfold greater glycogen content in the GSL3-transgenic muscle. Considering the water content and space associated with glycogen storage (16), the extensive glycogen macromolecule in GSL3-transgenic muscle may have disrupted myofibrillar mechanics.…”

Section: Discussionmentioning

confidence: 99%

Effect of glycogen synthase overexpression on insulin-stimulated muscle glucose uptake and storage

Fogt¹,

Pan²,

Lee³

et al. 2004

American Journal of Physiology-Endocrinology and Metabolism

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Ivy. Effect of glycogen synthase overexpression on insulin-stimulated muscle glucose uptake and storage. Am J Physiol Endocrinol Metab 286: E363-E369, 2004. First published October 21, 2003 10.1152/ ajpendo.00115.2003.-Insulin-stimulated muscle glucose uptake is inversely associated with the muscle glycogen concentration. To investigate whether this association is a cause and effect relationship, we compared insulin-stimulated muscle glucose uptake in noncontracted and postcontracted muscle of GSL3-transgenic and wild-type mice. GSL3-transgenic mice overexpress a constitutively active form of glycogen synthase, which results in an abundant storage of muscle glycogen. Muscle contraction was elicited by in situ electrical stimulation of the sciatic nerve. Right gastrocnemii from GSL3-transgenic and wild-type mice were subjected to 30 min of electrical stimulation followed by hindlimb perfusion of both hindlimbs. Thirty minutes of contraction significantly reduced muscle glycogen concentration in wild-type (49%) and transgenic (27%) mice, although transgenic mice retained 168.8 Ϯ 20.5 mol/g glycogen compared with 17.7 Ϯ 2.6 mol/g glycogen for wild-type mice. Muscle of transgenic and wildtype mice demonstrated similar pre-(3.6 Ϯ 0.3 and 3.9 Ϯ 0.6 mol⅐g Ϫ1 ⅐h Ϫ1 for transgenic and wild-type, respectively) and postcontraction (7.9 Ϯ 0.4 and 7.0 Ϯ 0.4 mol⅐g Ϫ1 ⅐h Ϫ1 for transgenic and wild-type, respectively) insulin-stimulated glucose uptakes. However, the [ 14 C]glucose incorporated into glycogen was greater in noncontracted (151%) and postcontracted (157%) transgenic muscle vs. muscle of corresponding wild-type mice. These results indicate that glycogen synthase activity is not rate limiting for insulin-stimulated glucose uptake in skeletal muscle and that the inverse relationship between muscle glycogen and insulin-stimulated glucose uptake is an association, not a cause and effect relationship. glucose transporter-4; glycogen synthesis; insulin; muscle contraction; protein kinase B/Akt INSULIN-STIMULATED GLUCOSE UPTAKE during postexercise recovery appears to be inversely related to the muscle glycogen concentration (5,6,14,18,33). When muscle glycogen is elevated above normal levels, the ability of insulin to activate glucose transport (6,12,14,20,25,33) and glycogen synthase (11, 27), the rate-limiting enzyme in glycogen synthesis, is significantly depressed. Several studies have demonstrated an inverse relationship between muscle glycogen concentration and the association of the glucose transporter GLUT4 with the plasma membrane following insulin stimulation (12,13,24). This may be a direct result of the glycogen macromolecule (8) or an indirect result of glycogen-mediated inhibition of PKB/ Akt (12, 25). PKB/Akt is a key insulin-signaling protein involved in stimulation of GLUT4 translocation to the plasma membrane (7,17,26,38) and inactivation of glycogen synthase kinase-3 (GSK-3) in skeletal muscle (9). GSK-3, in turn, has been implicated in inhibition of glycogen synthase (10). Thus PKB/Akt may play a pivot...

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Section: Discussionmentioning

confidence: 99%

Effect of glycogen synthase overexpression on insulin-stimulated muscle glucose uptake and storage

Fogt¹,

Pan²,

Lee³

et al. 2004

American Journal of Physiology-Endocrinology and Metabolism

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“…Glycogen is a highly branched (1 → 4)(1 → 6)-linked alpha-D -glucan with a molecular weight ranging from 1,000 to 1,000,000 kDa ( 11 ).…”

mentioning

confidence: 99%

Rapid Rehydration and Moderate Plasma Glucose Elevation by Fluid Containing Enzymatically Synthesized Glycogen

Inagaki

Ishihara

Ishida

et al. 2011

J Nutr Sci Vitaminol

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Summary Enzymatically synthesized glycogen (ESG) has high solubility and its solution has low osmotic pressure. Therefore ESG solution could be rapidly absorbed and could be adequate for water rehydration and carbohydrate supplementation during exercise. The object of this study was to evaluate the gastric emptying time and plasma glucose elevation after an administration of ESG solution in comparison with another carbohydrate solution by using a laboratory animal. Male BALB/c mice were administered 10% w/v solution of glucose, maltodextrin, starch, naturally synthesized glycogen (NSG) and ESG at a dose of 20 L/g body weight for the measurement of gastric emptying rate (Experiment 1) and 10 L/g body weight for the measurement of plasma glucose elevation (Experiment 2). The osmolarity of gastric content was lower in the ESG and maltodextrin group than the other carbohydrate group. Weight of gastric fluid was significantly lower in the ESG and water group than the glucose group ( p Ͻ 0.01). Plasma glucose level was significantly lower in the ESG group than the glucose group from 0 to 60 min after administration ( p Ͻ 0.01), whereas plasma glucose level was same from 60 to 120 min for the ESG and glucose group ( p ϭ 0.948). In Experiment 3, BALB/c mice ran on a treadmill for 2 h and were administered 8% of ESG or glucose solution (1.75, 3.5 or 7.0 L/g body weight) every 20 min during running. There was no difference in post-exercise muscle glycogen level. These data suggest that 1) ESG beverage does not disturb water absorption because of its short gastric emptying time and 2) ESG slowly elevates plasma glucose level and maintains it for a prolonged time compared to the glucose solution.

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“…Based on the results of electron microscopy, it has been shown that glycogen consists of spherical particles with diameters of 20-40 nm (β-particles), and that the β-particles often associate into much larger α-particles (∼200 nm). The molecular weight of an individual β-particle has been shown to be approximately 10 7 (Geddes 1986). Glycogen aqueous solution is opalescent (milky-white and slightly bluish), and gives a reddishbrown color on the addition of iodine.…”

Section: Glycogenmentioning

confidence: 99%

“…The polysaccharide is a highly branched (1→4)(1→6)-linked α-d-glucan with a high molecular weight (10 6 -10 9 ) (Geddes 1986). Based on the results of electron microscopy, it has been shown that glycogen consists of spherical particles with diameters of 20-40 nm (β-particles), and that the β-particles often associate into much larger α-particles (∼200 nm).…”

Section: Glycogenmentioning

confidence: 99%

In vitro synthesis of glycogen: the structure, properties, and physiological function of enzymatically-synthesized glycogen

et al. 2011

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This review describes a new enzymatic method for in vitro glycogen synthesis and its structure and properties. In this method, short-chain amylose is used as the substrate for branching enzymes (BE, EC 2.4.1.18). Although a kidney bean BE and Bacillus cereus BE could not synthesize high-molecular weight glucan, BEs from 6 other bacterial sources produced enzymatically synthesized glycogen (ESG). The BE from Aquifex aeolicus was the most suitable for the production of glycogen with a weight-average molecular weight (Mw) of 3,000-30,000 k. The molecular weight of the ESG is controllable by changing the concentration of the substrate amylose. Furthermore, the addition of amylomaltase (AM, EC 2.4.1.25) significantly enhanced the efficiency of this process, and the yield of ESG reached approximately 65%. Typical preparations of ESG obtained by this method were subjected to structural analyses. The average chain length, interior chain length, and exterior chain length of the ESGs were 8.2-11.6, 2.0-3.3, and 4.2-7.6, respectively. Transmission electron microscopy and intrinsic viscosity measurement showed that the ESG molecules formed spherical particles. Unlike starch, the ESGs were barely degraded by pullulanase. Solutions of ESG were opalescent (milky-white and slightly bluish), and gave a reddishbrown color on the addition of iodine. These analyses revealed that ESG shares similar molecular shapes and solution properties with natural-source glycogen. Moreover, ESG had macrophage-stimulating activity and its activity depends on the molecular weight of ESG. We successfully achieved large scale production of ESG. ESG could lead to new industrial applications, such as in the food, chemical, and pharmaceutical fields.

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Glycogen: A metabolic viewpoint

Cited by 56 publications

References 73 publications

Effect of glycogen synthase overexpression on insulin-stimulated muscle glucose uptake and storage

Effect of glycogen synthase overexpression on insulin-stimulated muscle glucose uptake and storage

Rapid Rehydration and Moderate Plasma Glucose Elevation by Fluid Containing Enzymatically Synthesized Glycogen

In vitro synthesis of glycogen: the structure, properties, and physiological function of enzymatically-synthesized glycogen

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