scholarly journals Regulation of glycogen synthase and phosphorylase activities by glucose and insulin in human skeletal muscle.

1987 ◽  
Vol 80 (1) ◽  
pp. 95-100 ◽  
Author(s):  
H Yki-Järvinen ◽  
D Mott ◽  
A A Young ◽  
K Stone ◽  
C Bogardus
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Glycogen Synthase

scholarly journals Contraction-mediated inactivation of glycogen synthase is accompanied by inactivation of glycogen synthase phosphatase in human skeletal muscle

1989 ◽  
Vol 259 (3) ◽  
pp. 901-904 ◽  
Author(s):  
Y Kida ◽  
A Katz ◽  
A D Lee ◽  
D M Mott
Keyword(s):  
Skeletal Muscle ◽  
Isometric Contraction ◽  
Human Skeletal Muscle ◽  
Glycogen Synthase ◽  
Active Form ◽  
Human Muscle ◽  
Maximal Voluntary Force ◽  
Before And After ◽  
Muscle Biopsies

Activities of glycogen synthase (GS) and GS phosphatase were determined on human muscle biopsies before and after isometric contraction at 2/3 maximal voluntary force. Total GS activity did not change during contraction (4.92 +/- 0.70 at rest versus 5.00 +/- 0.42 mmol/min per kg dry wt.; mean +/- S.E.M.), whereas both the active form of GS and the ratio of active form to total GS decreased by approximately 35% (P less than 0.01). GS phosphatase was inactivated in all subjects by an average of 39%, from 5.95 +/- 1.30 to 3.63 +/- 0.97 mmol/min per kg dry wt. (P less than 0.01). It is suggested that at least part of the contraction-induced inactivation of GS is due to an inactivation of GS phosphatase.

Induction of insulin resistance in human skeletal muscle cells by downregulation of glycogen synthase protein expression

Metabolism ◽  
2000 ◽  
Vol 49 (8) ◽  
pp. 962-968 ◽  
Author(s):  
K.S. Park ◽  
T.P. Ciaraldi ◽  
L. Carter ◽  
S. Mudaliar ◽  
S.E. Nikoulina ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Protein Expression ◽  
Human Skeletal Muscle ◽  
Glycogen Synthase ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Human Skeletal Muscle Cells

scholarly journals Glucagon-like peptide-1 (GLP-1) and glucose metabolism in human myocytes

2002 ◽  
Vol 173 (3) ◽  
pp. 465-473 ◽  
Author(s):  
MA Luque ◽  
N Gonzalez ◽  
L Marquez ◽  
A Acitores ◽  
A Redondo ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Metabolism ◽  
Human Skeletal Muscle ◽  
Glycogen Synthase ◽  
Second Messengers ◽  
Glycogen Synthesis ◽  
Human Muscle ◽  
Camp Content ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Glucagon-like peptide-1 (GLP-1) has been shown to have insulin-like effects upon the metabolism of glucose in rat liver, muscle and fat, and on that of lipids in rat and human adipocytes. These actions seem to be exerted through specific receptors which, unlike that of the pancreas, are not - at least in liver and muscle - cAMP-associated. Here we have investigated the effect, its characteristics, and possible second messengers of GLP-1 on the glucose metabolism of human skeletal muscle, in tissue strips and primary cultured myocytes. In muscle strips, GLP-1, like insulin, stimulated glycogen synthesis, glycogen synthase a activity, and glucose oxidation and utilization, and inhibited glycogen phosphorylase a activity, all of this at physiological concentrations of the peptide. In cultured myotubes, GLP-1 exerted, from 10(-13) mol/l, a dose-related increase of the D-[U-(14)C]glucose incorporation into glycogen, with the same potency as insulin, together with an activation of glycogen synthase a; the effect of 10(-11) mol/l GLP-1 on both parameters was additive to that induced by the equimolar amount of insulin. Synthase a was still activated in cells after 2 days of exposure to GLP-1, as compared with myotubes maintained in the absence of peptide. In human muscle cells, exendin-4 and its truncated form 9-39 amide (Ex-9) are both agonists of the GLP-1 effect on glycogen synthesis and synthase a activity; but while neither GLP-1 nor exendin-4 affected the cellular cAMP content after 5-min incubation in the absence of 3-isobutyl-1-methylxantine (IBMX), an increase was detected with Ex-9. GLP-1, exendin-4, Ex-9 and insulin all induced the prompt hydrolysis of glycosylphosphatidylinositols (GPIs). This work shows a potent stimulatory effect of GLP-1 on the glucose metabolism of human skeletal muscle, and supports the long-term therapeutic value of the peptide. Further evidence for a GLP-1 receptor in this tissue, different from that of the pancreas, is also illustrated, suggesting a role for an inositolphosphoglycan (IPG) as at least one of the possible second messengers of the GLP-1 action in human muscle.

Fasting inhibits insulin-mediated glycolysis and anaplerosis in human skeletal muscle

1991 ◽  
Vol 261 (5) ◽  
pp. E598-E605 ◽  
Author(s):  
C. E. Castillo ◽  
A. Katz ◽  
M. K. Spencer ◽  
Z. Yan ◽  
B. L. Nyomba
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Glycogen Synthase ◽  
Fat Free Mass ◽  
Whole Body ◽  
Glucose Disposal ◽  
Glycolytic Flux ◽  
Quadriceps Femoris Muscle ◽  
Before And After ◽  
Femoris Muscle

uglycemic (approximately 5.5 mM) hyperinsulinemic (60 mU.m-2.min-1) clamps were performed for 2 h after a 10-h fast and after a prolonged (72-h) fast. Biopsies were obtained from the quadriceps femoris muscle before and after each clamp. The rate of whole body glucose disposal was approximately 50% lower during the clamp after the 72-h fast (P less than or equal to 0.001). The increase in carbohydrate (CHO) oxidation (which is proportional to glycolysis) during the clamp after the 10-h fast (to 13.8 +/- 1.5 mumol.kg fat free mass-1.min-1) was completely abolished during the clamp after the 72-h fast (1.7 +/- 0.6; P less than or equal to 0.001). During the clamp after the 10-h fast, postphosphofructokinase (PFK) intermediates and malate in muscle increased, whereas glutamate decreased (P less than or equal to 0.05-0.001 vs. basal) and citrate did not change. During the clamp after the 72-h fast, there were no significant changes in post-PFK intermediates or glutamate (P greater than 0.05 vs. basal), but there was a decrease in citrate (P less than or equal to 0.01 vs. basal). Euglycemic hyperinsulinemia increased glycogen synthase fractional activity in muscle under both conditions but to a greater extent after the 72-h fast (P less than or equal to 0.01). It is concluded that insulin (after 10-h fast) increases glycolytic flux and the content of malate in muscle, which is probably due to increased anaplerosis.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Glucosamine Regulation of Glucose Metabolism in Cultured Human Skeletal Muscle Cells: Divergent Effects on Glucose Transport/Phosphorylation and Glycogen Synthase in Non-Diabetic and Type 2 Diabetic Subjects1

Endocrinology ◽  
1999 ◽  
Vol 140 (9) ◽  
pp. 3971-3980 ◽  
Author(s):  
Theodore P. Ciaraldi ◽  
Leslie Carter ◽  
Svetlana Nikoulina ◽  
Sunder Mudaliar ◽  
Donald A. McClain ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Glucose Metabolism ◽  
Glucose Transport ◽  
Human Skeletal Muscle ◽  
Glycogen Synthase ◽  
Muscle Cells ◽  
Skeletal Muscle Cells ◽  
Insulin Responsiveness ◽  
Type 2 Diabetic

Abstract Chronic exposure (48 h) to glucosamine resulted in a dose-dependent reduction of basal and insulin-stimulated glucose uptake activities in human skeletal muscle cell cultures from nondiabetic and type 2 diabetic subjects. Insulin responsiveness of uptake was also reduced. There was no change in total membrane expression of either GLUT1, GLUT3, or GLUT4 proteins. While glucosamine treatment had no significant effects on hexokinase activity measured in cell extracts, glucose phosphorylation in intact cells was impaired after treatment. Under conditions where glucose transport and phosphorylation were down regulated, the fractional velocity (FV) of glycogen synthase was increased by glucosamine treatment. Neither the total activity nor protein expression of glycogen synthase were influenced by glucosamine treatment. The stimulation of glycogen synthase by glucosamine was not due totally to soluble mediators. Reflective of the effects on transport/phosphorylation, total glycogen content and net glycogen synthesis were reduced after glucosamine treatment. These effects were similar in nondiabetic and type 2 cells. In summary: 1) Chronic treatment with glucosamine reduces glucose transport/phosphorylation and storage into glycogen in skeletal muscle cells in culture and impairs insulin responsiveness as well. 2) Down-regulation of glucose transport/phosphorylation occurs at a posttranslational level of GLUTs. 3) Glycogen synthase activity increases with glucosamine treatment. 4) Nondiabetic and type 2 muscle cells display equal sensitivity and responsiveness to glucosamine. Increased exposure of skeletal muscle to glucosamine, a substrate/precursor of the hexosamine pathway, alters intracellular glucose metabolism at multiple sites and can contribute to insulin resistance in this tissue.

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