Effect of the Type and Proportion of Dietary Carbohydrate on Serum Glucose Levels and Liver and Muscle Glycogen Synthesis in the Rat

1978 ◽  
Vol 22 (5) ◽  
pp. 313-320 ◽  
Author(s):  
A. Vrána ◽  
P. Fábry ◽  
L. Kazdová ◽  
K. Zvolánková
Keyword(s):  
Muscle Glycogen ◽  
Glycogen Synthesis ◽  
Serum Glucose ◽  
Dietary Carbohydrate ◽  
Glucose Levels ◽  
Muscle Glycogen Synthesis

Can photobiomodulation therapy (PBMT) control blood glucose levels and alter muscle glycogen synthesis?

2020 ◽  
Vol 207 ◽  
pp. 111877 ◽  
Author(s):  
Kenia Mendes Rodrigues Castro ◽  
Rodrigo Leal de Paiva Carvalho ◽  
Geraldo Marco Rosa Junior ◽  
Beatriz Antoniassi Tavares ◽  
Luis Henrique Simionato ◽  
...  
Keyword(s):  
Blood Glucose ◽  
Muscle Glycogen ◽  
Glycogen Synthesis ◽  
Photobiomodulation Therapy ◽  
Control Blood Glucose ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Muscle Glycogen Synthesis

DIURNAL VARIATIONS IN THE ACTION OF INSULIN ON MUSCLE GLYCOGEN SYNTHESIS

1974 ◽  
Vol 61 (2) ◽  
pp. 171-177 ◽  
Author(s):  
J. J. GAGLIARDINO ◽  
MARÍA TERESA PESSACQ
Keyword(s):  
Single Dose ◽  
Glycogen Synthesis ◽  
Serum Glucose ◽  
Time Of Day ◽  
Diaphragm Muscle ◽  
Circadian Variations ◽  
Glucose Levels ◽  
Hormone Injection ◽  
Muscle Glycogen Synthesis ◽  
Marked Decline

SUMMARY The effect of a single dose of insulin i.u./kg, i.p.) injected every 4 h during a 24-h period was studied in normal mice. The glycogen content of the diaphragm muscle and serum glucose levels were determined every 15 min throughout a period of 60 min after the hormone injection. Although insulin always produced an increase in glycogen and a decline in serum glucose, neither the sequential changes observed during the 60 min after injection nor the magnitude of these changes were constant throughout the 24 h of the day. The two circadian variations in the action of insulin (on glycogen and glucose) did not display any well-defined relationship, i.e. the most marked decline in glucose was not followed by a correspondingly marked increase in glycogen. These observations suggest that the results obtained from the administration of a single dose of insulin at an arbitrary time of day might be misleading. The circadian variations found could represent another component of the complex homeostatic mechanisms in which insulin is involved.

Update on Carbohydrate: Solid versus Liquid

1994 ◽  
Vol 4 (2) ◽  
pp. 80-88 ◽  
Author(s):  
Ellen Coleman
Keyword(s):  
Blood Glucose ◽  
Endurance Exercise ◽  
Glycogen Synthesis ◽  
Liver Glycogen ◽  
Serum Glucose ◽  
Carbohydrate Utilization ◽  
Carbohydrate Ingestion ◽  
Glucose Levels ◽  
Muscle Glycogen Synthesis ◽  
And Performance

Athletes often train or compete in athletic events that significantly reduce muscle and liver glycogen reserves. Carbohydrate ingestion before or during endurance exercise enhances performance by maintaining blood glucose levels and carbohydrate utilization. Also, an adequate intake of carbohydrate following endurance exercise helps to restore muscle and liver glycogen. This paper reviews the physiologic and performance benefits of solid versus liquid carbohydrate feedings before, during, and following endurance exercise. Solid and liquid carbohydrates are equally effective in raising blood glucose and enhancing performance when consumed during endurance exercise. Also, both forms of carbohydrate are similarly beneficial in promoting muscle glycogen synthesis after exercise. It is unclear whether solid and liquid carbohydrate feedings have the same effect on serum glucose and performance when consumed before exercise. Although limited research suggests that a low glycemic solid carbohydrate may represent the best preexercise meal choice, further research is needed to support this hypothesis.

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.

Effects of FFA on insulin-stimulated glucose fluxes and muscle glycogen synthase activity in rats

1998 ◽  
Vol 275 (2) ◽  
pp. E338-E344 ◽  
Author(s):  
Joong-Yeol Park ◽  
Chul-Hee Kim ◽  
Sung K. Hong ◽  
Kyo I. Suh ◽  
Ki-Up Lee
Keyword(s):  
Skeletal Muscle ◽  
Muscle Glycogen ◽  
Infusion Rate ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Glucose Infusion ◽  
Glucose Infusion Rate ◽  
Whole Body ◽  
Heparin Infusion ◽  
Muscle Glycogen Synthesis

To examine effects of free fatty acids (FFA) on insulin-stimulated glucose fluxes, euglycemic hyperinsulinemic (86 pmol ⋅ kg−1 ⋅ min−1) clamps were performed for 5 h in conscious rats with ( n = 8) or without ( n = 8) lipid-heparin infusion. Glucose infusion rate required to maintain euglycemia was not different between the two groups during the first 2 h of clamps but became significantly lower with lipid-heparin infusion in the 3rd h and thereafter. To investigate changes in intracellular glucose metabolism during lipid-heparin infusion, additional clamps ( n = 8 each) were performed for 1, 2, 3, or 5 h with an infusion of [3-3H]glucose. Insulin-stimulated whole body glucose utilization (Rd), glycolysis, and glycogen synthesis were estimated on the basis of tracer concentrations in plasma during the final 40 min of each clamp. Similar to changes in glucose infusion rate, Rd was not different between the two groups in the 1st and 2nd h but was significantly lower with lipid-heparin infusion in the 3rd h and thereafter. Whole body glycolysis was significantly lower with lipid-heparin infusion in all time periods, i.e., 1st, 2nd, 3rd, and 5th h of clamps. In contrast, whole body glycogen synthesis was higher with lipid-heparin infusion in the 1st and 2nd h but lower in the 5th h. Similarly, accumulation of [3H]glycogen radioactivity in muscle glycogen was significantly higher with lipid-heparin during the 1st and 2nd h but lower during the 3rd and 5th h. Glucose 6-phosphate (G-6- P) concentrations in gastrocnemius muscles were significantly higher with lipid-heparin infusion throughout the clamps. Muscle glycogen synthase (GS) activity was not altered with lipid-heparin infusion at 1, 2, and 3 h but was significantly lower at 5 h. Thus increased availability of FFA significantly reduced whole body glycolysis, but compensatory increase in skeletal muscle glycogen synthesis in association with accumulation of G-6- P masked this effect, and Rd was not affected in the early phase (within 2 h) of lipid-heparin infusion. Rd was reduced in the later phase (>2 h) of lipid-heparin infusion, when glycogen synthesis was reduced in association with reduced skeletal muscle GS activity.

Stimulatory effect of glutamine on glycogen accumulation in human skeletal muscle

1995 ◽  
Vol 269 (2) ◽  
pp. E309-E315 ◽  
Author(s):  
M. Varnier ◽  
G. P. Leese ◽  
J. Thompson ◽  
M. J. Rennie
Keyword(s):  
Muscle Glycogen ◽  
Glycogen Synthesis ◽  
Maximal Oxygen Consumption ◽  
Human Muscle ◽  
Glycogen Accumulation ◽  
Fractional Rate ◽  
Glucose Incorporation ◽  
Muscle Glycogen Synthesis ◽  
Exercise Muscle ◽  
Muscle Glycogen Concentration

To determine whether glutamine can stimulate human muscle glycogen synthesis, we studied in groups of six subjects the effect after exercise of infusion of glutamine, alanine+glycine, or saline. The subjects cycled for 90 min at 70-140% maximal oxygen consumption to deplete muscle glycogen; then primed constant infusions of glutamine (30 mg/kg; 50 mg.kg-1.h-1) or an isonitrogenous, isoenergetic mixture of alanine+glycine or NaCl (0.9%) were administered. Muscle glutamine remained constant during saline infusion, decreased 18% during alanine+glycine infusion (P < 0.001), but rose 16% during glutamine infusion (P < 0.001). By 2 h after exercise, muscle glycogen concentration had increased more in the glutamine-infused group than in the saline or alanine+glycine controls (+2.8 +/- 0.6, +0.8 +/- 0.4, and +0.9 +/- 0.4 mumol/g wet wt, respectively, P < 0.05, glutamine vs. saline or alanine+glycine). Labeling of glycogen by tracer [U-13C]glucose was similar in glutamine and saline groups, suggesting no effect of glutamine on the fractional rate of blood glucose incorporation into glycogen. The results suggest that, after exercise, increased availability of glutamine promotes muscle glycogen accumulation by mechanisms possibly including diversion of glutamine carbon to glycogen.

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