Regulation of hexokinase II and glycogen synthase mRNA, protein, and activity in human muscle

1995 ◽  
Vol 269 (4) ◽  
pp. E701-E708 ◽  
Author(s):  
L. J. Mandarino ◽  
R. L. Printz ◽  
K. A. Cusi ◽  
P. Kinchington ◽  
R. M. O'Doherty ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Insulin Infusion ◽  
Glycogen Synthase ◽  
Normal Subjects ◽  
Hexokinase Ii ◽  
Glut 4 ◽  
Before And After ◽  
Muscle Biopsies

Insulin regulates the activity of key enzymes of glucose metabolism in skeletal muscle by altering transcription or translation or by producing activity-altering modifications of preexisting enzyme molecules. Because of the small size of percutaneous muscle biopsies, these phenomena have been difficult to study in humans. This study was performed to determine how physiological hyperinsulinemia regulates the activities of hexokinase (HK), glycogen synthase (GS), and GLUT-4 in human skeletal muscle in vivo. We determined mRNA abundance, protein content, and activities for these proteins in muscle biopsies before and after a hyperinsulinemic clamp in normal subjects. HK I, HK II, GS, and GLUT-4 were expressed in muscle. HK II accounted for 80% of total HK activity and was increased by insulin from a basal value of 2.11 +/- 0.26 to 3.35 +/- 0.47 pmol.min-1.mg protein-1 (P < 0.05); HK I activity was unaffected. Insulin increased GS activity from 3.85 +/- 0.82 to 6.06 +/- 0.49 nmol.min-1.mg-1 (P < 0.01). HK II mRNA was increased 3.3 +/- 1.3-fold (P < 0.05) by insulin infusion. HK I, GS, and GLUT-4 mRNA and protein were unaffected. Because insulin infusion increased HK II but not GS mRNA, we conclude that HK II and GS may be regulated by insulin by different mechanisms in human skeletal muscle.

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.

scholarly journals Direct measurement of the lumped constant for 2-deoxy-[1-14C]glucose in vivo in human skeletal muscle

2000 ◽  
Vol 279 (1) ◽  
pp. E228-E233 ◽  
Author(s):  
Tapio Utriainen ◽  
Stefania Lovisatti ◽  
Sari Mäkimattila ◽  
Alessandra Bertoldo ◽  
Susan Weintraub ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Human Skeletal Muscle ◽  
Insulin Infusion ◽  
Normal Subjects ◽  
Normal Male ◽  
Wide Range ◽  
Lumped Constant ◽  
Male Subjects ◽  
Forearm Vein

The lumped constant (LC) is used to convert the clearance rate of 2-deoxy-d-glucose (2-DGcr) to that of glucose (Glccr). There are currently no data to validate the widely used assumption of an LC of 1.0 for human skeletal muscle. We determined the LC for 2-deoxy-[1-14C]glucose (2-DG) in 18 normal male subjects (age, 29 ± 2 yr; body mass index, 24.8 ± 0.8 kg/m2) after an overnight fast and during physiological (1 mU · kg−1· min−1insulin infusion for 180 min) and supraphysiological (5 mU · kg−1· min−1insulin infusion for 180 min) hyperinsulinemic conditions. Normoglycemia was maintained with the euglycemic clamp technique. The LC was measured directly with the use of a novel triple tracer-based method. [3-3H]glucose, 2-[1-14C]DG, and [12C]mannitol (Man) were injected as a bolus into the brachial artery. The concentrations of [3-3H]glucose and 2-[1-14C]DG (dpm/ml plasma) and of Man (μmol/l) were determined in 50 blood samples withdrawn from the ipsilateral deep forearm vein over 15 min after the bolus injection. The LC was calculated by a formula involving blood flow calculated from Man and the Glccrand 2-DGcr. The LC averaged 1.26 ± 0.08 (range 1.06–1.43), 1.15 ± 0.05 (0.99–1.39), and 1.18 ± 0.05 (0.97–1.37) under fasting conditions and during the 1 and 5 mU · kg−1· min−1insulin infusions (not significant between the different insulin concentrations, mean LC = 1.2, P < 0.01 vs. 1.0). We conclude that, in normal subjects, the LC for 2-DG in human skeletal muscle is constant over a wide range of insulin concentrations and averages 1.2.

Regulation of glucose transporter GLUT-4 and hexokinase II gene transcription by insulin and epinephrine

1997 ◽  
Vol 273 (4) ◽  
pp. E682-E687 ◽  
Author(s):  
Jared P. Jones ◽  
G. Lynis Dohm
Keyword(s):  
Skeletal Muscle ◽  
Gene Transcription ◽  
Glucose Transporter ◽  
Male Rats ◽  
Rat Skeletal Muscle ◽  
Hexokinase Ii ◽  
Epinephrine Infusion ◽  
Glut 4 ◽  
Gastrocnemius Muscles

Transport of glucose across the plasma membrane by GLUT-4 and subsequent phosphorylation of glucose by hexokinase II (HKII) constitute the first two steps of glucose utilization in skeletal muscle. This study was undertaken to determine whether epinephrine and/or insulin regulates in vivo GLUT-4 and HKII gene transcription in rat skeletal muscle. In the first experiment, adrenodemedullated male rats were fasted 24 h and killed in the control condition or after being infused for 1.5 h with epinephrine (30 μg/ml at 1.68 ml/h). In the second experiment, male rats were fasted 24 h and killed after being infused for 2.5 h at 1.68 ml/h with saline or glucose (625 mg/ml) or insulin (39.9 μg/ml) plus glucose (625 mg/ml). Nuclei were isolated from pooled quadriceps, tibialis anterior, and gastrocnemius muscles. Transcriptional run-on analysis indicated that epinephrine infusion decreased GLUT-4 and increased HKII transcription compared with fasted controls. Both glucose and insulin plus glucose infusion induced increases in GLUT-4 and HKII transcription of twofold and three- to fourfold, respectively, compared with saline-infused rats. In conclusion, epinephrine and insulin may regulate GLUT-4 and HKII genes at the level of transcription in rat skeletal muscle.

Effects of 7 wk of endurance training on human skeletal muscle metabolism during submaximal exercise

2004 ◽  
Vol 97 (6) ◽  
pp. 2148-2153 ◽  
Author(s):  
Paul J. LeBlanc ◽  
Krista R. Howarth ◽  
Martin J. Gibala ◽  
George J. F. Heigenhauser
Keyword(s):  
Skeletal Muscle ◽  
Endurance Training ◽  
Glycogen Phosphorylase ◽  
Human Skeletal Muscle ◽  
Vastus Lateralis ◽  
Muscle Metabolism ◽  
Allosteric Modulators ◽  
Before And After ◽  
First Time ◽  
Muscle Biopsies

This is the first study to examine the effects of endurance training on the activation state of glycogen phosphorylase (Phos) and pyruvate dehydrogenase (PDH) in human skeletal muscle during exercise. We hypothesized that 7 wk of endurance training (Tr) would result in a posttransformationally regulated decrease in flux through Phos and an attenuated activation of PDH during exercise due to alterations in key allosteric modulators of these important enzymes. Eight healthy men (22 ± 1 yr) cycled to exhaustion at the same absolute workload (206 ± 5 W; ∼80% of initial maximal oxygen uptake) before and after Tr. Muscle biopsies (vastus lateralis) were obtained at rest and after 5 and 15 min of exercise. Fifteen minutes of exercise post-Tr resulted in an attenuated activation of PDH (pre-Tr: 3.75 ± 0.48 vs. post-Tr: 2.65 ± 0.38 mmol·min−1·kg wet wt−1), possibly due in part to lower pyruvate content (pre-Tr: 0.94 ± 0.14 vs. post-Tr: 0.46 ± 0.03 mmol/kg dry wt). The decreased pyruvate availability during exercise post-Tr may be due to a decreased muscle glycogenolytic rate (pre-Tr: 13.22 ± 1.01 vs. post-Tr: 7.36 ± 1.26 mmol·min−1·kg dry wt−1). Decreased glycogenolysis was likely mediated, in part, by posttransformational regulation of Phos, as evidenced by smaller net increases in calculated muscle free ADP (pre-Tr: 111 ± 16 vs. post-Tr: 84 ± 10 μmol/kg dry wt) and Pi (pre-Tr: 57.1 ± 7.9 vs. post-Tr: 28.6 ± 5.6 mmol/kg dry wt). We have demonstrated for the first time that several signals act to coordinately regulate Phos and PDH, and thus carbohydrate metabolism, in human skeletal muscle after 7 wk of endurance training.

Increments in skeletal muscle GLUT-1 and GLUT-4 after endurance training in humans

1996 ◽  
Vol 270 (3) ◽  
pp. E456-E462 ◽  
Author(s):  
S. M. Phillips ◽  
X. X. Han ◽  
H. J. Green ◽  
A. Bonen
Keyword(s):  
Skeletal Muscle ◽  
Time Course ◽  
Human Skeletal Muscle ◽  
Prolonged Exercise ◽  
Mitochondrial Potential ◽  
Glut 1 ◽  
Glut 4 ◽  
Induced Changes ◽  
Muscle Biopsies ◽  
Early Training

We investigated the time course of training-induced changes in the expression of GLUT-1 and GLUT-4 in human skeletal muscle. Seven healthy males trained for 2 h/day (approximately 60% pretraining VO2peak) for 31 days (31D). Muscle biopsies were obtained before training (PRE) and after 5 (5D) and 31 days (31D) of training. Training resulted in progressive increases in muscle GLUT-4 with increasing training duration (PRE<5D<31D; P<0.01). Muscle GLUT-1 content was also increased (P<0.05) after training; however, the increase was not observed until 31D (131%). Increases in muscle hexokinase (HK) activity were complete by 5D (P<0.01). Muscle malate dehydrogenase activity was not elevated after 5D of training but was increased (+35%; P<0.01) at 31D. Results from this study show that increases in both GLUT-4 and HK represent early training-induced adaptations to prolonged exercise training. As training progresses, further increases in GLUT-4, but not HK, occur in conjunction with an increase in muscle mitochondrial potential and GLUT-1.

Rat skeletal muscle hexokinase II mRNA and activity are increased by a single bout of acute exercise

1994 ◽  
Vol 266 (2) ◽  
pp. E171-E178 ◽  
Author(s):  
R. M. O'Doherty ◽  
D. P. Bracy ◽  
H. Osawa ◽  
D. H. Wasserman ◽  
D. K. Granner
Keyword(s):  
Skeletal Muscle ◽  
Acute Exercise ◽  
Recovery Period ◽  
Exhaustive Exercise ◽  
Male Rats ◽  
Hexokinase Ii ◽  
Glut 4 ◽  
Heat Stable ◽  
Single Bout

This study addresses the potential role of skeletal muscle hexokinase (HK) II in the regulation of glucose uptake and metabolism in vivo. Male rats undertook a single bout of treadmill exercise and were then killed immediately or after a predetermined recovery period. Three muscles [soleus (Sol), gastrocnemius/plantaris (Gc), and white vastus] were excised, and HK II mRNA, GLUT-4 mRNA, total HK (HK I and HK II) and heat-stable HK (predominantly HK I) activities were assessed. Three hours after the cessation of a single bout of exhaustive exercise, HK II mRNA was significantly increased in all three muscles. Ninety or thirty minutes of exercise, with a 3-h recovery, increased Gc HK II mRNA to the same extent as exhaustive exercise, but 15 min of exercise had no effect. Gc HK II mRNA continued to increase up to 8 h after the cessation of 90 min of exercise but returned to basal by 24 h postexercise. In contrast to HK II mRNA, Gc GLUT-4 mRNA was unchanged at 0, 3, 8, and 24 h after the cessation of 90 min of exercise. Total HK activity was significantly increased in Sol and Gc, 8 and 24 h after the cessation of 90 min of exercise. Heat-stable HK activity was unchanged in all three muscles. The increase in total HK activity, inferred to be an increase of HK II, may be important in the persistence of the postexercise increase in insulin action.

Effect of insulin on intracellular pH and phosphate metabolism in human skeletal muscle in vivo

1991 ◽  
Vol 81 (1) ◽  
pp. 123-128 ◽  
Author(s):  
D. J. Taylor ◽  
S. W. Coppack ◽  
T. A. D. Cadoux-Hudson ◽  
G. J. Kemp ◽  
G. K. Radda ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Intracellular Ph ◽  
Inorganic Phosphate ◽  
Human Skeletal Muscle ◽  
Muscle Metabolism ◽  
Normal Subjects ◽  
Phosphate Concentration ◽  
Resonance Spectroscopy ◽  
Phosphorus Containing

1. 31P nuclear magnetic resonance spectroscopy and the hyperinsulinaemic-euglycaemic clamp were used simultaneously to assess the effect of insulin on intracellular pH and the major phosphorus-containing metabolites of normal human skeletal muscle in vivo in four normal subjects. 2. Insulin and glucose were infused for 120 min. Plasma insulin increased approximately 10-fold over pre-clamp levels (5.6 ± 0.9 m-units/l pre-clamp and 54 ± 5 m-units/l over the last hour of infusion; mean ± sem, n = 4). Plasma glucose concentration did not change significantly (5.4 ± 0.2 mmol/l pre-clamp and 5.5 ± 0.1 mmol/l over the last hour of infusion). 3. Insulin and glucose infusion resulted in a decline in the intracellular pH of forearm muscle of 0.027 ± 0.007 unit/h (P < 0.01), whereas in control studies of the same subjects, pH rose by 0.046 ± 0.005 unit/h (P < 0.001). 4. In the clamp studies, intracellular inorganic phosphate concentration rose by 18%/h, whereas ATP, phosphocreatine and phosphomonoester concentrations did not change. In plasma, inorganic phosphate concentration was 1.16 ± 0.05 mmol/l before infusion, and this decreased by a mean rate of 0.14 mmol h−1 l−1. No change was observed in any of these intracellular metabolites in the control studies. 5. The results show that, under physiological conditions, insulin does not raise intracellular pH in human muscle, and thus cannot influence muscle metabolism by this mechanism. The results also suggest that insulin causes a primary increase in the next flux of inorganic phosphate across the muscle cell membrane.

Insulin induces translocation of GLUT-4 glucose transporters in human skeletal muscle

1995 ◽  
Vol 268 (4) ◽  
pp. E613-E622 ◽  
Author(s):  
A. Guma ◽  
J. R. Zierath ◽  
H. Wallberg-Henriksson ◽  
A. Klip
Keyword(s):  
Skeletal Muscle ◽  
Plasma Membrane ◽  
Human Skeletal Muscle ◽  
Molecular Mechanisms ◽  
Glucose Transporter ◽  
Vastus Lateralis ◽  
Glucose Transporters ◽  
Membrane Markers ◽  
Glut 4 ◽  
Muscle Biopsies

Understanding the molecular mechanisms involved in the regulation of glucose transport into human muscle is necessary to unravel possible defects in glucose uptake associated with insulin resistance in humans. Here we report a strategy to subfractionate human skeletal muscle biopsies (0.5 g) removed from vastus lateralis during a euglycemic insulinemic clamp procedure. A sucrose gradient separated total membranes into five fractions. Fraction 25 (25% sucrose) contained the plasma membrane markers alpha 1- and alpha 2-subunits of the Na(+)-K(+)-adenosinetriphosphatase and the GLUT-5 hexose transporter, recently immunolocalized to the cell surface of human skeletal muscle. The dihydropyridine receptor, a transverse tubule marker, was present exclusively in this fraction. The GLUT-4 glucose transporter was more concentrated in fraction 27.5 (27.5% sucrose) and largely diminished in plasma membrane markers. Open skeletal muscle biopsies were removed before and 30 min after clamping insulin to 550 pM. This increased GLUT-4 protein by 1.61-fold in fraction 25 and lowered it by 50% in fraction 27.5. Thus physiological concentrations of insulin induce translocation of glucose transporters from an internal membrane pool to surface membranes in human skeletal 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)

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