Additive effect of contraction and insulin on glucose uptake and glycogen synthase in muscle with different glycogen contents

2010 ◽  
Vol 108 (5) ◽  
pp. 1106-1115 ◽  
Author(s):  
Yu-Chiang Lai ◽  
Elham Zarrinpashneh ◽  
Jørgen Jensen
Keyword(s):  
Protein Kinase ◽  
Glucose Uptake ◽  
Skeletal Muscles ◽  
Glycogen Content ◽  
Glycogen Synthase ◽  
Additive Effect ◽  
Insulin Stimulation ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase ◽  
Pkb Phosphorylation

Insulin and contraction regulate glucose uptake and glycogen synthase (GS) via distinct mechanisms in skeletal muscles, and an additive effect has been reported. Glycogen content is known to influence both contraction- and insulin-stimulated glucose uptake and GS activity. Our study reports that contraction and insulin additively stimulate glucose uptake in rat epitrochlearis muscles with normal (NG) and high (HG) glycogen contents, but the additive effect was only partial. In muscles with low glycogen (LG) content no additive effect was seen, but glucose uptake was higher in LG than in NG and HG during contraction, insulin stimulation, and when the two stimuli were combined. In LG, contraction-stimulated AMP-activated protein kinase (AMPK) activity and insulin-stimulated PKB phosphorylation were higher than in NG and HG, but phosphorylation of Akt substrate of 160 kDa was not elevated correspondingly. GLUT4 content was 50% increased in LG (rats fasted 24 h), which may explain the increased glucose uptake. Contraction and insulin also additively increased GS fractional activity in NG and HG but not in LG. GS fractional activity correlated most strongly with GS Ser641 phosphorylation ( R −0.94, P < 0.001). GS fractional activity also correlated with GS Ser7,10 phosphorylation, but insulin did not reduce GS Ser7,10 phosphorylation. In conclusion, an additive effect of contraction and insulin on glucose uptake and GS activity occurs in muscles with normal and high glycogen content but not in muscles with low glycogen content. Furthermore, contraction, insulin, and glycogen content all regulate GS Ser641 phosphorylation and GS fractional activity in concert.

Muscle-specific overexpression of wild type and R225Q mutant AMP-activated protein kinase γ3-subunit differentially regulates glycogen accumulation

2006 ◽  
Vol 291 (3) ◽  
pp. E557-E565 ◽  
Author(s):  
Haiyan Yu ◽  
Michael F. Hirshman ◽  
Nobuharu Fujii ◽  
Jason M. Pomerleau ◽  
Lauren E. Peter ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
Glycogen Content ◽  
Specific Activity ◽  
Glycogen Synthase ◽  
Underlying Mechanism ◽  
Wild Type ◽  
Glycogen Accumulation ◽  
Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK) is a heterotrimeric complex that works as an energy sensor to integrate nutritional and hormonal signals. The naturally occurring R225Q mutation in the γ3-subunit in pigs is associated with abnormally high glycogen content in skeletal muscle. Becauses skeletal muscle accounts for most of the body's glucose uptake, and γ3 is specifically expressed in skeletal muscle, it is important to understand the underlying mechanism of this mutation in regulating glucose and glycogen metabolism. Using skeletal muscle-specific transgenic mice overexpressing wild type γ3 (WTγ3) and R225Q mutant γ3 (MUTγ3), we show that both WTγ3 and MUTγ3 mice have 1.5- to 2-fold increases in muscle glycogen content. In WTγ3 mice, increased glycogen content was associated with elevated total glycogen synthase activity and reduced glycogen phosphorylase activity, whereas alterations in activities of these enzymes could not explain elevated glycogen in MUTγ3 mice. Basal, 5-aminoimidazole- AICAR- and phenformin-stimulated AMPKα2 isoform-specific activities were decreased only in MUTγ3 mice. Basal rates of 2-DG glucose uptake were decreased in both WTγ3 and MUTγ3 mice. However, AICAR- and phenformin-stimulated 2-DG glucose uptake were blunted only in MUTγ3 mice. In conclusion, expression of either wild type or mutant γ3-subunit of AMPK results in increased glycogen concentrations in muscle, but the mechanisms underlying this alteration appear to be different. Furthermore, mutation of the γ3-subunit is associated with decreases in AMPKα2 isoform-specific activity and impairment in AICAR- and phenformin-stimulated skeletal muscle glucose uptake.

scholarly journals Insulin directly stimulates mitochondrial glucose oxidation in the heart

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Qutuba G. Karwi ◽  
Cory S. Wagg ◽  
Tariq R. Altamimi ◽  
Golam M. Uddin ◽  
Kim L. Ho ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Glucose Uptake ◽  
Glucose Oxidation ◽  
Glycogen Synthase ◽  
Acid Oxidation ◽  
Mouse Heart ◽  
Insulin Stimulation ◽  
Direct Stimulation ◽  
Gsk 3Β ◽  
Stimulation Of

Abstract Background Glucose oxidation is a major contributor to myocardial energy production and its contribution is orchestrated by insulin. While insulin can increase glucose oxidation indirectly by enhancing glucose uptake and glycolysis, it also directly stimulates mitochondrial glucose oxidation, independent of increasing glucose uptake or glycolysis, through activating mitochondrial pyruvate dehydrogenase (PDH), the rate-limiting enzyme of glucose oxidation. However, how insulin directly stimulates PDH is not known. To determine this, we characterized the impacts of modifying mitochondrial insulin signaling kinases, namely protein kinase B (Akt), protein kinase C-delta (PKC-δ) and glycogen synthase kinase-3 beta (GSK-3β), on the direct insulin stimulation of glucose oxidation. Methods We employed an isolated working mouse heart model to measure the effect of insulin on cardiac glycolysis, glucose oxidation and fatty acid oxidation and how that could be affected when mitochondrial Akt, PKC-δ or GSK-3β is disturbed using pharmacological modulators. We also used differential centrifugation to isolate mitochondrial and cytosol fraction to examine the activity of Akt, PKC-δ and GSK-3β between these fractions. Data were analyzed using unpaired t-test and two-way ANOVA. Results Here we show that insulin-stimulated phosphorylation of mitochondrial Akt is a prerequisite for transducing insulin’s direct stimulation of glucose oxidation. Inhibition of mitochondrial Akt completely abolishes insulin-stimulated glucose oxidation, independent of glucose uptake or glycolysis. We also show a novel role of mitochondrial PKC-δ in modulating mitochondrial glucose oxidation. Inhibition of mitochondrial PKC-δ mimics insulin stimulation of glucose oxidation and mitochondrial Akt. We also demonstrate that inhibition of mitochondrial GSK3β phosphorylation does not influence insulin-stimulated glucose oxidation. Conclusion We identify, for the first time, insulin-stimulated mitochondrial Akt as a prerequisite transmitter of the insulin signal that directly stimulates cardiac glucose oxidation. These novel findings suggest that targeting mitochondrial Akt is a potential therapeutic approach to enhance cardiac insulin sensitivity in condition such as heart failure, diabetes and obesity.

scholarly journals Role of Hypothalamic Adenosine 5′-Monophosphate-Activated Protein Kinase in the Impaired Counterregulatory Response Induced by Repetitive Neuroglucopenia

Endocrinology ◽  
2007 ◽  
Vol 148 (3) ◽  
pp. 1367-1375 ◽  
Author(s):  
Thierry Alquier ◽  
Junji Kawashima ◽  
Youki Tsuji ◽  
Barbara B. Kahn
Keyword(s):  
Protein Kinase ◽  
Glycogen Content ◽  
Glucose Sensor ◽  
Critical Role ◽  
Glucose Sensing ◽  
Dorsomedial Hypothalamus ◽  
Hormone Responses ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

Antecedent hypoglycemia blunts counterregulatory responses that normally restore glycemia, a phenomenon known as hypoglycemia-associated autonomic failure (HAAF). The mechanisms leading to impaired counterregulatory responses are largely unknown. Hypothalamic AMP-activated protein kinase (AMPK) acts as a glucose sensor. To determine whether failure to activate AMPK could be involved in the etiology of HAAF, we developed a model of HAAF using repetitive intracerebroventricular (icv) injection of 2-deoxy-d-glucose (2DG) resulting in transient neuroglucopenia in normal rats. Ten minutes after a single icv injection of 2DG, both α1- and α2-AMPK activities were increased 30–50% in arcuate and ventromedial/dorsomedial hypothalamus but not in other hypothalamic regions, hindbrain, or cortex. Increased AMPK activity persisted in arcuate hypothalamus at 60 min after 2DG injection when serum glucagon and corticosterone levels were increased 2.5- to 3.4-fold. When 2DG was injected icv daily for 4 d, hypothalamic α1- and α2-AMPK responses were markedly blunted in arcuate hypothalamus, and α1-AMPK was also blunted in mediobasal hypothalamus 10 min after 2DG on d 4. Both AMPK isoforms were activated normally in arcuate hypothalamus at 60 min. Counterregulatory hormone responses were impaired by recurrent neuroglucopenia and were partially restored by icv injection of 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside, an AMPK activator, before 2DG. Glycogen content increased 2-fold in hypothalamus after recurrent neuroglucopenia, suggesting that glycogen supercompensation could be involved in down-regulating the AMPK glucose-sensing pathway in HAAF. Thus, activation of hypothalamic AMPK may be important for the full counterregulatory hormone response to neuroglucopenia. Furthermore, impaired or delayed AMPK activation in specific hypothalamic regions may play a critical role in the etiology of HAAF.

scholarly journals Effect of acute activation of 5′-AMP-activated protein kinase on glycogen regulation in isolated rat skeletal muscle

2007 ◽  
Vol 102 (3) ◽  
pp. 1007-1013 ◽  
Author(s):  
Licht Miyamoto ◽  
Taro Toyoda ◽  
Tatsuya Hayashi ◽  
Shin Yonemitsu ◽  
Masako Nakano ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Muscle Glycogen ◽  
Glycogen Synthase ◽  
Glycogen Synthesis ◽  
Glycolytic Flux ◽  
Ampk Activation ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase ◽  
Isolated Rat

5′-AMP-activated protein kinase (AMPK) has been implicated in glycogen metabolism in skeletal muscle. However, the physiological relevance of increased AMPK activity during exercise has not been fully clarified. This study was performed to determine the direct effects of acute AMPK activation on muscle glycogen regulation. For this purpose, we used an isolated rat muscle preparation and pharmacologically activated AMPK with 5-aminoimidazole-4-carboxamide-1-β-d-ribonucleoside (AICAR). Tetanic contraction in vitro markedly activated the α1- and α2-isoforms of AMPK, with a corresponding increase in the rate of 3- O-methylglucose uptake. Incubation with AICAR elicited similar enhancement of AMPK activity and 3- O-methylglucose uptake in rat epitrochlearis muscle. In contrast, whereas contraction stimulated glycogen synthase (GS), AICAR treatment decreased GS activity. Insulin-stimulated GS activity also decreased after AICAR treatment. Whereas contraction activated glycogen phosphorylase (GP), AICAR did not alter GP activity. The muscle glycogen content decreased in response to contraction but was unchanged by AICAR. Lactate release was markedly increased when muscles were stimulated with AICAR in buffer containing glucose, indicating that the glucose taken up into the muscle was catabolized via glycolysis. Our results suggest that AMPK does not mediate contraction-stimulated glycogen synthesis or glycogenolysis in skeletal muscle and also that acute AMPK activation leads to an increased glycolytic flux by antagonizing contraction-stimulated glycogen synthesis.

AMP-activated protein kinase regulation and action in skeletal muscle during exercise

2003 ◽  
Vol 31 (1) ◽  
pp. 191-195 ◽  
Author(s):  
N. Musi ◽  
H. Yu ◽  
L.J. Goodyear
Keyword(s):  
Protein Kinase ◽  
Exercise Training ◽  
Metabolic Pathways ◽  
Acute Exercise ◽  
Glycogen Content ◽  
Glycogen Metabolism ◽  
Acid Oxidation ◽  
Ampk Activity ◽  
Energy Sensing ◽  
Amp Activated Protein Kinase

Physical exercise increases muscle glucose uptake, enhances insulin sensitivity and leads to fatty acid oxidation in muscle. The AMP-activated protein kinase (AMPK) is an energy-sensing enzyme that is strongly activated during muscle contraction due to acute decreases in ATP/AMP and phosphocreatine/creatine ratios. Accumulating evidence suggests that AMPK plays an important role in mediating these metabolic processes. Furthermore, AMPK has been implicated in regulating gene transcription and therefore may play a role in some of the cellular adaptations to training exercise. There is also evidence that changes in AMPK activity result in altered cellular glycogen content, suggesting that this enzyme regulates glycogen metabolism. Recent studies have shown that the magnitude of AMPK activation and associated metabolic responses are affected by factors such as glycogen content, exercise training and fibre type. In summary, AMPK regulates several metabolic pathways during acute exercise and modifies the expression of many genes involved in the adaptive changes to exercise training.

scholarly journals Chronic hypoxia increases insulin-stimulated glucose uptake in mouse soleus muscle

2011 ◽  
Vol 300 (1) ◽  
pp. R85-R91 ◽  
Author(s):  
J. L. Gamboa ◽  
Mary L. Garcia-Cazarin ◽  
Francisco H. Andrade
Keyword(s):  
Blood Glucose ◽  
Insulin Sensitivity ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
Soleus Muscle ◽  
Chronic Hypoxia ◽  
Glycogen Synthase ◽  
Glucose Levels ◽  
Amp Activated Protein Kinase

People living at high altitude appear to have lower blood glucose levels and decreased incidence of diabetes. Faster glucose uptake and increased insulin sensitivity are likely explanations for these findings: skeletal muscle is the largest glucose sink in the body, and its adaptation to the hypoxia of altitude may influence glucose uptake and insulin sensitivity. This study tested the hypothesis that chronic normobaric hypoxia increases insulin-stimulated glucose uptake in soleus muscles and decreases plasma glucose levels. Adult male C57BL/6J mice were kept in normoxia [fraction of inspired O2 = 21% (Control)] or normobaric hypoxia [fraction of inspired O2 = 10% (Hypoxia)] for 4 wk. Then blood glucose and insulin levels, in vitro muscle glucose uptake, and indexes of insulin signaling were measured. Chronic hypoxia lowered blood glucose and plasma insulin [glucose: 14.3 ± 0.65 mM in Control vs. 9.9 ± 0.83 mM in Hypoxia ( P < 0.001); insulin: 1.2 ± 0.2 ng/ml in Control vs. 0.7 ± 0.1 ng/ml in Hypoxia ( P < 0.05)] and increased insulin sensitivity determined by homeostatic model assessment 2 [21.5 ± 3.8 in Control vs. 39.3 ± 5.7 in Hypoxia ( P < 0.03)]. There was no significant difference in basal glucose uptake in vitro in soleus muscle (1.59 ± 0.24 and 1.71 ± 0.15 μmol·g−1·h−1 in Control and Hypoxia, respectively). However, insulin-stimulated glucose uptake was 30% higher in the soleus after 4 wk of hypoxia than Control (6.24 ± 0.23 vs. 4.87 ± 0.37 μmol·g−1·h−1, P < 0.02). Muscle glycogen content was not significantly different between the two groups. Levels of glucose transporters 4 and 1, phosphoinositide 3-kinase, glycogen synthase kinase 3, protein kinase B/Akt, and AMP-activated protein kinase were not affected by chronic hypoxia. Akt phosphorylation following insulin stimulation in soleus muscle was significantly (25%) higher in Hypoxia than Control ( P < 0.05). Neither glycogen synthase kinase 3 nor AMP-activated protein kinase phosphorylation changed after 4 wk of hypoxia. These results demonstrate that the adaptation of skeletal muscles to chronic hypoxia includes increased insulin-stimulated glucose uptake.

Effects of adenosine on myocardial glucose and palmitate metabolism after transient ischemia: role of 5′-AMP-activated protein kinase

2006 ◽  
Vol 291 (4) ◽  
pp. H1883-H1892 ◽  
Author(s):  
Jagdip S. Jaswal ◽  
Manoj Gandhi ◽  
Barry A. Finegan ◽  
Jason R. B. Dyck ◽  
Alexander S. Clanachan
Keyword(s):  
Protein Kinase ◽  
Glucose Uptake ◽  
Glycogen Synthesis ◽  
Transient Ischemia ◽  
Palmitate Oxidation ◽  
Adrenoceptor Antagonist ◽  
Ampk Phosphorylation ◽  
Proton Production ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

Loss of cardioprotection by adenosine in hearts stressed by transient ischemia may be due to its effects on glucose metabolism. In the absence of transient ischemia, adenosine inhibits glycolysis, whereas it accelerates glycolysis after transient ischemia. Inasmuch as 5′-AMP-activated protein kinase (AMPK) is implicated as a regulator of glucose and fatty acid utilization, this study determined whether a differential alteration of AMPK activity contributes to acceleration of glycolysis by adenosine in hearts stressed by transient ischemia. Studies were performed in working rat hearts perfused aerobically under normal conditions or after transient ischemia (two 10-min periods of ischemia followed by 5 min of reperfusion). LV work was not affected by adenosine. AMPK phosphorylation was not affected by transient ischemia; however, phosphorylation and activity were increased nine- and threefold, respectively, by adenosine in stressed hearts. Phosphorylation of acetyl-CoA carboxylase and rates of palmitate oxidation were unaltered. Glycolysis and calculated proton production were increased 1.8- and 1.7-fold, respectively, in hearts with elevated AMPK activity. Elevated AMPK activity was associated with inhibition of glycogen synthesis and unchanged rates of glucose uptake and glycogenolysis. Phentolamine, an α-adrenoceptor antagonist, which prevents adenosine-induced activation of glycolysis in stressed hearts, prevented AMPK phosphorylation. These data demonstrate that adenosine-induced activation of AMPK after transient ischemia is not sufficient to alter palmitate oxidation or glucose uptake. Rather, activation of AMPK alters partitioning of glucose away from glycogen synthesis; the increase in glycolysis may in part contribute to loss of adenosine-induced cardioprotection in hearts subjected to transient ischemia.

scholarly journals Hydrogen Sulfide Impairs Glucose Utilization and Increases Gluconeogenesis in Hepatocytes

Endocrinology ◽  
2013 ◽  
Vol 154 (1) ◽  
pp. 114-126 ◽  
Author(s):  
Ling Zhang ◽  
Guangdong Yang ◽  
Ashley Untereiner ◽  
Youngjun Ju ◽  
Lingyun Wu ◽  
...  
Keyword(s):  
Hydrogen Sulfide ◽  
Protein Kinase ◽  
Glucose Uptake ◽  
Hepg2 Cells ◽  
Phosphoenolpyruvate Carboxykinase ◽  
Glucose Utilization ◽  
Glycogen Content ◽  
Glycogen Synthesis ◽  
Primary Mouse ◽  
Amp Activated Protein Kinase

Mounting evidence has established hydrogen sulfide (H2S) as an important gasotransmitter with multifaceted physiological functions. The aim of the present study was to investigate the role of H2S on glucose utilization, glycogen synthesis, as well as gluconeogenesis in both HepG2 cells and primary mouse hepatocytes. Incubation with NaHS (a H2S donor) impaired glucose uptake and glycogen storage in HepG2 cells via decreasing glucokinase activity. Adenovirus-mediated cystathionine γ-lyase (CSE) overexpression increased endogenous H2S production and lowered glycogen content in HepG2 cells. Glycogen content was significantly higher in liver tissues from CSE knockout (KO) mice compared to that from wild type (WT) mice in fed condition. Glucose consumption was less in primarily cultured hepatocytes isolated from WT mice than those from CSE KO mice, but more glucose was produced by hepatocytes via gluconeogenesis and glycogenolysis pathways in WT mice than in CSE KO mice. NaHS treatment reduced the phosphorylation of AMP-activated protein kinase, whereas stimulation of AMP-activated protein kinase by 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside reversed H2S-impaired glucose uptake. H2S-increased glucose production was likely through increased phosphoenolpyruvate carboxykinase activity. In addition, insulin at the physiological range inhibited CSE expression, and H2S decreased insulin-stimulated phosphorylation of Akt in HepG2 cells. CSE expression was increased, however, in insulin-resistant state induced by exposing cells to high levels of insulin (500 nm) and glucose (33 mm) for 24 h. Taken together, these data suggest that the interaction of H2S and insulin in liver plays a pivotal role in regulating insulin sensitivity and glucose metabolism.

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