Caffeine and contraction synergistically stimulate 5′-AMP-activated protein kinase and insulin-independent glucose transport in rat skeletal muscle

The AMP-activated protein kinase (AMPK) has been hypothesized to mediate contraction and 5-aminoimidazole-4-carboxamide 1-β-d-ribonucleoside (AICAR)-induced increases in glucose uptake in skeletal muscle. The purpose of the current study was to determine whether treadmill exercise and isolated muscle contractions in rat skeletal muscle increase the activity of the AMPKα1 and AMPKα2 catalytic subunits in a dose-dependent manner and to evaluate the effects of the putative AMPK inhibitors adenine 9-β-d-arabinofuranoside (ara-A), 8-bromo-AMP, and iodotubercidin on AMPK activity and 3- O-methyl-d-glucose (3-MG) uptake. There were dose-dependent increases in AMPKα2 activity and 3-MG uptake in rat epitrochlearis muscles with treadmill running exercise but no effect of exercise on AMPKα1 activity. Tetanic contractions of isolated epitrochlearis muscles in vitro significantly increased the activity of both AMPK isoforms in a dose-dependent manner and at a similar rate compared with increases in 3-MG uptake. In isolated muscles, the putative AMPK inhibitors ara-A, 8-bromo-AMP, and iodotubercidin fully inhibited AICAR-stimulated AMPKα2 activity and 3-MG uptake but had little effect on AMPKα1 activity. In contrast, these compounds had absent or minimal effects on contraction-stimulated AMPKα1 and -α2 activity and 3-MG uptake. Although the AMPKα1 and -α2 isoforms are activated during tetanic muscle contractions in vitro, in fast-glycolytic fibers, the activation of AMPKα2-containing complexes may be more important in regulating exercise-mediated skeletal muscle metabolism in vivo. Development of new compounds will be required to study contraction regulation of AMPK by pharmacological inhibition.

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Effect of Quercetin Treatment on Mitochondrial Biogenesis and Exercise-Induced AMP-Activated Protein Kinase Activation in Rat Skeletal Muscle

Nutrients ◽

10.3390/nu12030729 ◽

2020 ◽

Vol 12 (3) ◽

pp. 729 ◽

Cited By ~ 1

Author(s):

Keiichi Koshinaka ◽

Asuka Honda ◽

Hiroyuki Masuda ◽

Akiko Sato

Keyword(s):

Skeletal Muscle ◽

Protein Kinase ◽

Endurance Exercise ◽

Mitochondrial Biogenesis ◽

Exercise Performance ◽

Term Therapy ◽

High Dose ◽

Rat Skeletal Muscle ◽

Amp Activated Protein Kinase ◽

Quercetin Treatment

The purpose of this study was to evaluate the effect of chronic quercetin treatment on mitochondrial biogenesis, endurance exercise performance and activation levels of AMP-activated protein kinase (AMPK) in rat skeletal muscle. Rats were assigned to a control or quercetin group and were fed for 7 days. Rats treated with quercetin showed no changes in the protein levels of citrate synthase or cytochrome C oxidase IV or those of sirtuin 1, peroxisome proliferator-activated receptor gamma coactivator-1α or phosphorylated AMPK. After endurance swimming exercise, quercetin-treated rats demonstrated no differences in blood and muscle lactate levels or glycogen utilization speed compared to control rats. These results indicate that quercetin treatment does not stimulate mitochondrial biogenesis in skeletal muscle and does not influence metabolism in a way that might enhance endurance exercise capacity. On the other hand, the AMPK phosphorylation level immediately after exercise was significantly lower in quercetin-treated muscles, suggesting that quercetin treatment might provide a disadvantage to muscle adaptation when administered with exercise training. The molecular results of this study indicate that quercetin treatment may not be advantageous for improving endurance exercise performance, at least after high-dose and short-term therapy.

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Inactivation of acetyl-CoA carboxylase and activation of AMP-activated protein kinase in muscle during exercise

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1996.270.2.e299 ◽

1996 ◽

Vol 270 (2) ◽

pp. E299-E304 ◽

Cited By ~ 188

Author(s):

W. W. Winder ◽

D. G. Hardie

Keyword(s):

Skeletal Muscle ◽

Fatty Acid ◽

Protein Kinase ◽

Ammonium Sulfate ◽

Quadriceps Muscle ◽

Acid Oxidation ◽

Acetyl Coa Carboxylase ◽

Rat Skeletal Muscle ◽

Malonyl Coa ◽

Amp Activated Protein Kinase

Malonyl-CoA, an inhibitor of fatty acid oxidation in skeletal muscle mitochondria, decreases in rat skeletal muscle during exercise or in response to electrical stimulation. Regulation of rat skeletal muscle acetyl-CoA carboxylase (ACC), the enzyme that synthesizes malonyl-CoA, was studied in vitro and in vivo. Avidin-Sepharose affinity-purified ACC from hindlimb skeletal muscle was phosphorylated by purified liver AMP-activated protein kinase with a concurrent decrease in ACC activity. AMP-activated protein kinase was quantitated in resuspended ammonium sulfate precipitates of the fast-twitch red (type IIa fibers) region of the quadriceps muscle. Rats running on a treadmill at 21 m/min up a 15% grade show a 2.4-fold activation of AMP-activated protein kinase concurrently with a marked decrease in ACC activity in the resuspended ammonium sulfate precipitates at all citrate concentrations ranging from 0 to 20 mM. Malonyl-CoA decreased from a resting value of 1.85 +/- 0.29 to 0.50 +/- 0.09 nmol/g in red quadriceps muscle after 30 min of treadmill running. The activation of the AMP-activated protein kinase with consequent phosphorylation and inactivation of ACC may be one of the primary events in the control of malonyl-CoA and hence fatty acid oxidation during exercise.

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Possible involvement of the α1 isoform of 5′AMP-activated protein kinase in oxidative stress-stimulated glucose transport in skeletal muscle

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00487.2003 ◽

2004 ◽

Vol 287 (1) ◽

pp. E166-E173 ◽

Cited By ~ 98

Author(s):

Taro Toyoda ◽

Tatsuya Hayashi ◽

Licht Miyamoto ◽

Shin Yonemitsu ◽

Masako Nakano ◽

...

Keyword(s):

Oxidative Stress ◽

Skeletal Muscle ◽

Protein Kinase ◽

Glucose Transport ◽

Activation Process ◽

Dependent Manner ◽

Upstream Kinase ◽

Metabolic Stresses ◽

Amp Activated Protein Kinase

Recent studies have suggested that 5′AMP-activated protein kinase (AMPK) is activated in response to metabolic stresses, such as contraction, hypoxia, and the inhibition of oxidative phosphorylation, which leads to insulin-independent glucose transport in skeletal muscle. In the present study, we hypothesized that acute oxidative stress increases the rate of glucose transport via an AMPK-mediated mechanism. When rat epitrochlearis muscles were isolated and incubated in vitro in Krebs buffer containing the oxidative agent H2O2, AMPKα1 activity increased in a time- and dose-dependent manner, whereas AMPKα2 activity remained unchanged. The activation of AMPKα1 was associated with phosphorylation of AMPK Thr172, suggesting that an upstream kinase is involved in the activation process. H2O2-induced AMPKα1 activation was blocked in the presence of the antioxidant N-acetyl-l-cysteine (NAC), and H2O2 significantly increased the ratio of oxidized glutathione to glutathione (GSSG/GSH) concentrations, a sensitive marker of oxidative stress. H2O2 did not cause an increase in the conventional parameters of AMPK activation, such as AMP and AMP/ATP. H2O2 increased 3- O-methyl-d-glucose transport, and this increase was partially, but significantly, blocked in the presence of NAC. Results were similar when the muscles were incubated in a superoxide-generating system using hypoxanthine and xanthine oxidase. Taken together, our data suggest that acute oxidative stress activates AMPKα1 in skeletal muscle via an AMP-independent mechanism and leads to an increase in the rate of glucose transport, at least in part, via an AMPKα1-mediated mechanism.

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