scholarly journals Glucose-dependent insulinotropic polypeptide directly induces glucose transport in rat skeletal muscle

2015 ◽  
Vol 309 (3) ◽  
pp. R295-R303 ◽  
Author(s):  
Laelie A. Snook ◽  
Emery M. Nelson ◽  
David J. Dyck ◽  
David C. Wright ◽  
Graham P. Holloway
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transport ◽  
Soleus Muscle ◽  
Serum Insulin ◽  
Current Data ◽  
Signaling Mechanism ◽  
Akt Phosphorylation ◽  
Glucose Challenge ◽  
Muscle Glucose Transport

Several gastrointestinal proteins have been identified to have insulinotropic effects, including glucose-dependent insulinotropic polypeptide (GIP); however, the direct effects of incretins on skeletal muscle glucose transport remain largely unknown. Therefore, the purpose of the current study was to examine the role of GIP on skeletal muscle glucose transport and insulin signaling in rats. Relative to a glucose challenge, a mixed glucose+lipid oral challenge increased circulating GIP concentrations, skeletal muscle Akt phosphorylation, and improved glucose clearance by ∼35% ( P < 0.05). These responses occurred without alterations in serum insulin concentrations. In an incubated soleus muscle preparation, GIP directly stimulated glucose transport and increased GLUT4 accumulation on the plasma membrane in the absence of insulin. Moreover, the ability of GIP to stimulate glucose transport was mitigated by the addition of the PI 3-kinase (PI3K) inhibitor wortmannin, suggesting that signaling through PI3K is required for these responses. We also provide evidence that the combined stimulatory effects of GIP and insulin on soleus muscle glucose transport are additive. However, the specific GIP receptor antagonist (Pro3)GIP did not attenuate GIP-stimulated glucose transport, suggesting that GIP is not signaling through its classical receptor. Together, the current data provide evidence that GIP regulates skeletal muscle glucose transport; however, the exact signaling mechanism(s) remain unknown.

Role of the AMPKγ3 isoform in hypoxia-stimulated glucose transport in glycolytic skeletal muscle

2009 ◽  
Vol 297 (6) ◽  
pp. E1388-E1394 ◽  
Author(s):  
Atul S. Deshmukh ◽  
Stephan Glund ◽  
Robby Z. Tom ◽  
Juleen R. Zierath
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transport ◽  
Competitive Inhibitor ◽  
Energy Status ◽  
Wild Type ◽  
Ampk Activity ◽  
Energy Sensing ◽  
Edl Muscle ◽  
Muscle Glucose Transport

Skeletal muscle glucose transport is regulated via the canonical insulin-signaling cascade as well as by energy-sensing signals. 5′-AMP-activated protein kinase (AMPK) has been implicated in the energy status regulation of glucose transport. We determined the role of the AMPKγ3 isoform in hypoxia-mediated energy status signaling and glucose transport in fast-twitch glycolytic extensor digitorum longus (EDL) muscle from AMPKγ3-knockout (KO) mice and wild-type mice. Although hypoxia increased glucose transport ( P < 0.001) in wild-type mice, this effect was attenuated in AMPKγ3-KO mice (45% reduction, P < 0.01). The role of Ca2+-mediated signaling was tested using the Ca2+/calmodulin competitive inhibitor KN-93. KN-93 exposure reduced hypoxia-mediated glucose transport in AMPKγ3-KO and wild-type mice ( P < 0.05). To further explore the underlying signaling mechanisms, phosphorylation of CaMKII, AMPK, ACC, and TBC1D1/D4 as well as isoform-specific AMPK activity was determined. Basal and hypoxia-mediated phosphorylation of CaMKII, AMPK, and ACC as well as α1- and α2-associated AMPK activity was comparable between AMPKγ3-KO and wild-type mice. KN-93 reduced hypoxia-mediated CaMKII phosphorylation in AMPKγ3-KO and wild-type mice ( P < 0.05), whereas phosphorylation of AMPK and ACC as well as α1- and α2-associated AMPK activity was unaltered. Hypoxia increased TBC1D1/D4 phosphorylation in AMPKγ3-KO and wild-type mice ( P < 0.001). KN-93 exposure prevented this effect in AMPKγ3-KO, but not in wild-type mice. Taken together, we provide direct evidence for a role of the AMPKγ3 isoform in hypoxia-mediated glucose transport in glycolytic muscle. Moreover, hypoxia-mediated TBC1D1/D4 phosphorylation was uncoupled from glucose transport in AMPKγ3-KO mice, indicating that TBC1D1/D4-independent mechanisms contribute to glucose transport in skeletal muscle.

Essential role of p38 MAPK for activation of skeletal muscle glucose transport by lithium

2007 ◽  
Vol 113 (4-5) ◽  
pp. 221-227 ◽  
Author(s):  
Nicholas B. Harrell ◽  
Mary K. Teachey ◽  
Nancy J. Gifford ◽  
Erik J. Henriksen
Keyword(s):  
Skeletal Muscle ◽  
Glucose Transport ◽  
P38 Mapk ◽  
Essential Role ◽  
Muscle Glucose Transport

Modulation of glucose transport in skeletal muscle by reactive oxygen species

2007 ◽  
Vol 102 (4) ◽  
pp. 1671-1676 ◽  
Author(s):  
Abram Katz
Keyword(s):  
Reactive Oxygen Species ◽  
Skeletal Muscle ◽  
Glucose Transport ◽  
Reactive Oxygen ◽  
Convincing Evidence ◽  
Oxygen Species ◽  
Carbohydrate Utilization ◽  
Muscle Glucose Transport ◽  
Amp Activated Protein Kinase

Glucose transport is an essential physiological process that is characteristic of all eukaryotic cells, including skeletal muscle. In skeletal muscle, glucose transport is mediated by the GLUT-4 protein under conditions of increased carbohydrate utilization. The three major physiological stimuli of glucose transport in muscle are insulin, exercise/contraction, and hypoxia. Here, the role of reactive oxygen species (ROS) in modulating glucose transport in skeletal muscle is reviewed. Convincing evidence for ROS involvement in insulin- and hypoxia-mediated transport in muscle is lacking. Recent experiments, based on pharmacological and genetic approaches, support a role for ROS in contraction-mediated glucose transport. During contraction, endogenously produced ROS appear to mediate their effects on glucose transport via AMP-activated protein kinase.

scholarly journals Skeletal Muscle Glucose Transport and Metabolism Are Enhanced in Transgenic Mice Overexpressing the Glut4 Glucose Transporter.

1995 ◽  
Vol 270 (4) ◽  
pp. 1679-1684
Author(s):  
Polly A. Hansen ◽  
Eric A. Gulve ◽  
Bess Adkins Marshall ◽  
Jiaping Gao ◽  
Jeffrey E. Pessin ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Transgenic Mice ◽  
Glucose Transport ◽  
Glucose Transporter ◽  
Muscle Glucose Transport

Isomer-specific actions of conjugated linoleic acid on muscle glucose transport in the obese Zucker rat

2003 ◽  
Vol 285 (1) ◽  
pp. E98-E105 ◽  
Author(s):  
Erik J. Henriksen ◽  
Mary K. Teachey ◽  
Zachary C. Taylor ◽  
Stephan Jacob ◽  
Arne Ptock ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Skeletal Muscle ◽  
Glucose Tolerance ◽  
Glucose Transport ◽  
Zucker Rat ◽  
Transport Activity ◽  
Insulin Resistant ◽  
Obese Zucker Rat ◽  
Cla Isomers ◽  
Muscle Glucose Transport

The fatty acid-conjugated linoleic acid (CLA) enhances glucose tolerance and insulin action on skeletal muscle glucose transport in rodent models of insulin resistance. However, no study has directly compared the metabolic effects of the two primary CLA isomers, cis-9, trans-11-CLA (c9,t11-CLA) and trans-10, cis-12-CLA (t10,c12-CLA). Therefore, we assessed the effects of a 50:50 mixture of these two CLA isomers (M-CLA) and of preparations enriched in either c9,t11-CLA (76% enriched) or t10,c12-CLA (90% enriched) on glucose tolerance and insulin-stimulated glucose transport in skeletal muscle of the insulin-resistant obese Zucker ( fa/ fa) rat. Animals were treated daily by gavage with either vehicle (corn oil), M-CLA, c9,t11-CLA, or t10,c12-CLA (all CLA treatments at 1.5 g total CLA/kg body wt) for 21 consecutive days. During an oral glucose tolerance test, glucose responses were reduced ( P < 0.05) by 10 and 16%, respectively, in the M-CLA and t10,c12-CLA animals, respectively, whereas insulin responses were diminished by 21 and 19% in these same groups. There were no significant alterations in these responses in the c9,t11-CLA group. Insulin-mediated glucose transport activity was enhanced by M-CLA treatment in both type I soleus (32%) and type IIb epitrochlearis (58%) muscles and by 36 and 48%, respectively, with t10,c12-CLA. In the soleus, these increases were associated with decreases in protein carbonyls (index of oxidative stress, r = -0.616, P = 0.0038) and intramuscular triglycerides ( r = -0.631, P = 0.0028). Treatment with c9,t11-CLA was without effect on these variables. These results suggest that the ability of CLA treatment to improve glucose tolerance and insulin-stimulated glucose transport activity in insulin-resistant skeletal muscle of the obese Zucker rat are associated with a reduction in oxidative stress and muscle lipid levels and can be specifically ascribed to the actions of the t10,c12 isomer. In the obese Zucker rat, the c9,t11 isomer of CLA is metabolically neutral.

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