Rapid activation of glycogen synthase and protein phosphatase in human skeletal muscle after isometric contraction requires an intact circulation

1995 ◽  
Vol 431 (2) ◽  
pp. 259-265 ◽  
Author(s):  
Abram Katz ◽  
Itamar Raz
Keyword(s):  
Skeletal Muscle ◽  
Isometric Contraction ◽  
Protein Phosphatase ◽  
Human Skeletal Muscle ◽  
Glycogen Synthase ◽  
Rapid Activation

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.

No Change in Insulin Mediators in Human Skeletal Muscle During Isometric Contraction or Recovery

1996 ◽  
Vol 28 (10) ◽  
pp. 545-548 ◽  
Author(s):  
A. Katz ◽  
E. Hultma ◽  
L. Huang ◽  
C. Villar-Palasi ◽  
J. Larner
Keyword(s):  
Skeletal Muscle ◽  
Isometric Contraction ◽  
Human Skeletal Muscle

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 The inhibition of glycogen synthase kinase-3 by insulin or insulin-like growth factor 1 in the rat skeletal muscle cell line L6 is blocked by wortmannin, but not by rapamycin: evidence that wortmannin blocks activation of the mitogen-activated protein kinase pathway in L6 cells between Ras and Raf

1994 ◽  
Vol 303 (1) ◽  
pp. 21-26 ◽  
Author(s):  
D A E Cross ◽  
D R Alessi ◽  
J R Vandenheede ◽  
H E McDowell ◽  
H S Hundal ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Map Kinase ◽  
Protein Phosphatase ◽  
Glycogen Synthase ◽  
Glycogen Synthase Kinase 3 ◽  
Rat Skeletal Muscle ◽  
S6 Kinase ◽  
P70 S6 Kinase ◽  
Skeletal Muscle Cell Line ◽  
Stimulation Of

Glycogen synthase kinase-3 (GSK3) is inactivated in vitro by p70 S6 kinase or MAP kinase-activated protein kinase-1 beta (MAPKAP kinase-1 beta; also known as Rsk-2). Here we show that GSK3 isoforms are inhibited by 40% within minutes after stimulation of the rat skeletal-muscle cell line L6 with insulin-like growth factor-1 (IGF-1) or insulin. GSK3 was similarly inhibited in rabbit skeletal muscle after an intravenous injection of insulin. Inhibition resulted from increased phosphorylation of GSK3, probably at a serine/threonine residue(s), because it was reversed by incubation with protein phosphatase-2A. Rapamycin blocked the activation of p70 S6 kinase by IGF-1 in L6 cells, but had no effect on the inhibition of GSK3 or the activation of MAPKAP kinase-1 beta. In contrast, wortmannin, a potent inhibitor of PtdIns 3-kinase, prevented the inactivation of GSK3 and the activation of MAPKAP kinase-1 beta and p70 S6 kinase by IGF-1 or insulin. Wortmannin also blocked the activation of p74raf-1. MAP kinase kinase and p42 MAP kinase, but not the formation of GTP-Ras by IGF-1. The results suggest that the stimulation of glycogen synthase by insulin/IGF-1 in skeletal muscle involves the MAP-KAP kinase-1-catalysed inhibition of GSK3, as well as the previously described activation of the glycogen-associated form of protein phosphatase-1.

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.

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
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