AMPK activation with AICAR provokes an acute fall in plasma [K+]

2008 ◽  
Vol 294 (1) ◽  
pp. C126-C135 ◽  
Author(s):  
Dan Zheng ◽  
Anjana Perianayagam ◽  
Donna H. Lee ◽  
M. Douglas Brannan ◽  
Li E. Yang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Infusion Rate ◽  
Extracellular Fluid ◽  
Ampk Activation ◽  
Conscious Rats ◽  
Significant Fall ◽  
Ampk Phosphorylation ◽  
Atp Levels ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

AMP-activated protein kinase (AMPK), activated by an increase in intracellular AMP-to-ATP ratio, stimulates pathways that can restore ATP levels. We tested the hypothesis that AMPK activation influences extracellular fluid (ECF) K+ homeostasis. In conscious rats, AMPK was activated with 5-aminoimidazole-4-carboxamide-1-beta-d-ribofuranoside (AICAR) infusion: 38.4 mg/kg bolus then 4 mg·kg−1·min−1 infusion. Plasma [K+] and [glucose] both dropped at 1 h of AICAR infusion and [K+] dropped to 3.3 ± 0.04 mM by 3 h, linearly related to the increase in muscle AMPK phosphorylation. AICAR treatment did not increase urinary K+ excretion. AICAR lowered [K+] whether plasma [K+] was chronically elevated or lowered. The K+ infusion rate needed to maintain baseline plasma [K+] reached 15.7 ± 1.3 μmol K+·kg−1·min−1 between 120 and 180 min AICAR infusion. In mice expressing a dominant inhibitory form of AMPK in the muscle (Tg-KD1), baseline [K+] was not different from controls (4.2 ± 0.1 mM), but the fall in plasma [K+] in response to AICAR (0.25 g/kg) was blunted: [K+] fell to 3.6 ± 0.1 in controls and to 3.9 ± 0.1 mM in Tg-KD1, suggesting that ECF K+ redistributes, at least in part, to muscle ICF. In summary, these findings illustrate that activation of AMPK activity with AICAR provokes a significant fall in plasma [K+] and suggest a novel mechanism for redistributing K+ from ECF to ICF.

scholarly journals AMP-activated protein kinase phosphorylation of the R domain inhibits PKA stimulation of CFTR

2009 ◽  
Vol 297 (1) ◽  
pp. C94-C101 ◽  
Author(s):  
J Darwin King ◽  
Adam C. Fitch ◽  
Jeffrey K. Lee ◽  
Jill E. McCane ◽  
Don-On Daniel Mak ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Dominant Negative ◽  
Ampk Phosphorylation ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase ◽  
Stimulation Of ◽  
In Cells ◽  
R Domain

The metabolic sensor AMP-activated protein kinase (AMPK) has emerged as an important link between cellular metabolic status and ion transport activity. We previously found that AMPK binds to and phosphorylates CFTR in vitro and inhibits PKA-dependent stimulation of CFTR channel gating in Calu-3 bronchial serous gland epithelial cells. To further characterize the mechanism of AMPK-dependent regulation of CFTR, whole cell patch-clamp measurements were performed with PKA activation in Calu-3 cells expressing either constitutively active or dominant-negative AMPK mutants (AMPK-CA or AMPK-DN). Baseline CFTR conductance in cells expressing AMPK-DN was substantially greater than controls, suggesting that tonic AMPK activity in these cells inhibits CFTR under basal conditions. Although baseline CFTR conductance in cells expressing AMPK-CA was comparable to that of controls, PKA stimulation of CFTR was completely blocked in AMPK-CA-expressing cells, suggesting that AMPK activation renders CFTR resistant to PKA activation in vivo. Phosphorylation studies of CFTR in human embryonic kidney-293 cells using tetracycline-inducible expression of AMPK-DN demonstrated AMPK-dependent phosphorylation of CFTR in vivo. However, AMPK activity modulation had no effect on CFTR in vivo phosphorylation in response to graded doses of PKA or PKC agonists. Thus, AMPK-dependent CFTR phosphorylation renders the channel resistant to activation by PKA and PKC without preventing phosphorylation by these kinases. We found that Ser768, a CFTR R domain residue considered to be an inhibitory PKA site, is the dominant site of AMPK phosphorylation in vitro. Ser-to-Ala mutation at this site enhanced baseline CFTR activity and rendered CFTR resistant to inhibition by AMPK, suggesting that AMPK phosphorylation at Ser768 is required for its inhibition of CFTR. In summary, our findings indicate that AMPK-dependent phosphorylation of CFTR inhibits CFTR activation by PKA, thereby tuning the PKA-responsiveness of CFTR to metabolic and other stresses in the cell.

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.

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 AMPK Activation of Flavonoids from Psidium guajava Leaves in L6 Rat Myoblast Cells and L02 Human Hepatic Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Jiankuan Li ◽  
Yujing Zhao ◽  
Lingya Cao ◽  
Qinghong Zheng ◽  
Jianping Gao
Keyword(s):  
Protein Kinase ◽  
Psidium Guajava ◽  
Structure Identification ◽  
Significant Activity ◽  
Ampk Activation ◽  
Hepatic Cells ◽  
Ampk Activity ◽  
Myoblast Cells ◽  
Amp Activated Protein Kinase ◽  
L02 Cells

Objective. To isolate the hypoglycemic bioactive components from leaves of Psidium guajava and evaluate their AMP-activated protein kinase (AMPK) activities. Methods. A variety of column chromatography was used for the isolation of compounds, and nuclear magnetic resonance (NMR) and mass spectrum (MS) were used for the structure identification of compounds. AMP-activated protein kinase (AMPK) activity of compounds obtained from leaves of Psidium guajava was evaluated in L6 rat myoblast cells and L02 human hepatic cells by western blot. Results. Six principal flavonoids largely present in the leaves of Psidium guajava, quercetin (1), quercetin-3-O-α-L-arabinofuranoside (2), quercetin-3-O-α-L-arabinopyranoside (3), quercetin-3-O-β-D-galactopyranoside (4), quercetin-3-O-β-D-glucopyranoside (5), and quercetin-3-O-β-D-xylopyranoside (6), were obtained and compound 1–6 exhibited significant activity on AMPK activation both in L6 cells and L02 cells (p<0.01) compared with Control. In particular, the effects of quercetin on AMPK activation were extremely significant compared with Control (p<0.001). Conclusions. These findings demonstrated that these flavonoids had potential for the activation of AMPK and hypoglycemic activity.

scholarly journals Regulation of glucose transport by the AMP-activated protein kinase

2004 ◽  
Vol 63 (2) ◽  
pp. 205-210 ◽  
Author(s):  
Nobuharu Fujii ◽  
William G. Aschenbach ◽  
Nicolas Musi ◽  
Michael F. Hirshman ◽  
Laurie J. Goodyear
Keyword(s):  
Protein Kinase ◽  
Glucose Transport ◽  
Glycogen Content ◽  
Acid Oxidation ◽  
Ampk Activation ◽  
Muscle Biology ◽  
Ampk Activity ◽  
Energy Sensing ◽  
Amp Activated Protein Kinase

The AMP-activated protein kinase (AMPK) is an energy-sensing enzyme that is activated during exercise and muscle contraction as a result of acute decreases in ATP:AMP and phosphocreatine:creatine. Physical exercise increases muscle glucose uptake, enhances insulin sensitivity and leads to fatty acid oxidation in muscle. An important issue in muscle biology is to understand whether AMPK plays a role in mediating these metabolic processes. AMPK has also been implicated in regulating gene transcription and, therefore, may function in some of the cellular adaptations to training exercise. 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. There have also been conflicting reports as to whether AMPK activity is necessary for contraction-stimulated glucose transport. Thus, during the next several years considerably more research will be necessary in order to fully understand the role of AMPK in regulating glucose transport in skeletal muscle.

Abstract 2321: Reactive Oxygen Species-Induced Activation of 5′AMP-Activated Protein Kinase Mediates Cardioprotection Against Ischemia and Reperfusion Injury

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Geert Onderwater ◽  
Nazha Hamdani ◽  
M. Jumoke A Vreden ◽  
Jeroen Steenhuisen ◽  
Etto C Eringa ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Protein Kinase ◽  
Infarct Size ◽  
Control Group ◽  
Ischemia And Reperfusion ◽  
Oxygen Species ◽  
Ampk Activation ◽  
Ischemia And Reperfusion Injury ◽  
Ampk Phosphorylation ◽  
Amp Activated Protein Kinase

The myocardium possesses intrinsic protective mechanisms against ischemia and reperfusion injury (I/R). 5′AMP-activated protein kinase (AMPK) is known as regulator of cellular energy status and is reduced during diabetes mellitus. Recently, AMPK is also implicated in ischemic preconditioning leading to cardioprotection against I/R. We hypothesize that AMPK is involved in anesthetic-induced cardioprotection and that this AMPK activation is evoked by production of reactive oxygen species (ROS). Isolated Langendorff-perfused rat hearts were subjected to 35 minutes of global ischemia followed by 120 minutes of reperfusion. Hearts were divided into 2 groups: a Control group and a Sevo group receiving three times 5-minute episodes of 2.5 vol% sevoflurane before I/R. AMPK phosphorylation was determined with Western Blot analysis. Cardioprotection was assessed as recovery of left ventricular pressure after I/R and as infarct size using triphenyltetrazolium chloride staining. In the Control group, I/R resulted in a twofold increase in phosphorylation levels of AMPK (Control 1.0 ± 0.1 vs. Control-I/R: 2.3 ± 0.1 a.u., n = 4, p < 0.05). Sevoflurane preconditioning did not immediately, prior to ischemia, affect the AMPK phosphorylation (Sevo 0.9 ± 0.2 vs. Control 1.0 ± 0.2, n = 6), but doubled the increase in AMPK phosphorylation to control after ischemia (Sevo-I: 2.0 ± 0.5 (vs. Control-I), n = 6, p < 0.05), as well as after I/R (Sevo-I/R: 2.1 ± 0.3 vs. (Control-I/R), n = 6, p < 0.05). The AMPK-inhibitor compound C (1 and 10 μM) reduced the increase in AMPK phosphorylation and abolished the cardioprotection derived from functional recovery and infarct size. In addition, the ROS-scavenger n-(2-mercaptopropionyl)-glycine (MPG, 1mM) also reduced the sevoflurane-mediated increase in AMPK phosphorylation and completely prevented cardioprotection. These results demonstrate for the first time a direct link between AMPK activation and the production of ROS in cardioprotection. We conclude that anesthetic-induced AMPK activation protects the heart against I/R and relies on production of ROS, which might be especially important in the context of impaired cardioprotection in the diabetic myocardium.

Role of AMP-activated protein kinase in healthy and diseased hearts

2006 ◽  
Vol 291 (6) ◽  
pp. H2557-H2569 ◽  
Author(s):  
Vernon W. Dolinsky ◽  
Jason R. B. Dyck
Keyword(s):  
Energy Metabolism ◽  
Protein Kinase ◽  
Cardiac Myocyte ◽  
Acid Oxidation ◽  
Ampk Activation ◽  
Cardiac Energy Metabolism ◽  
Ampk Activity ◽  
Cardiac Energy ◽  
Metabolic Stresses ◽  
Amp Activated Protein Kinase

The heart is capable of utilizing a variety of substrates to produce the necessary ATP for cardiac function. AMP-activated protein kinase (AMPK) has emerged as a key regulator of cellular energy homeostasis and coordinates multiple catabolic and anabolic pathways in the heart. During times of acute metabolic stresses, cardiac AMPK activation seems to be primarily involved in increasing energy-generating pathways to maintain or restore intracellular ATP levels. In acute situations such as mild ischemia or short durations of severe ischemia, activation of cardiac AMPK appears to be necessary for cardiac myocyte function and survival by stimulating ATP generation via increased glycolysis and accelerated fatty acid oxidation. Whereas AMPK activation may be essential for adaptation of cardiac energy metabolism to acute and/or minor metabolic stresses, it is unknown whether AMPK activation becomes maladaptive in certain chronic disease states and/or extreme energetic stresses. However, alterations in cardiac AMPK activity are associated with a number of cardiovascular-related diseases such as pathological cardiac hypertrophy, myocardial ischemia, glycogen storage cardiomyopathy, and Wolff-Parkinson-White syndrome, suggesting the possibility of a maladaptive role. Although the precise role AMPK plays in the diseased heart is still in question, it is clear that AMPK is a major regulator of cardiac energy metabolism. The consequences of alterations in AMPK activity and subsequent cardiac energy metabolism in the healthy and the diseased heart will be discussed.

scholarly journals Sex Differences in Cardiac AMP-Activated Protein Kinase Following Exhaustive Exercise

2020 ◽  
Vol 4 (01) ◽  
pp. E13-E18
Author(s):  
Kevin D. Brown ◽  
Edward D. Waggy ◽  
Sreejayan Nair ◽  
Timothy J. Robinson ◽  
Emily E. Schmitt ◽  
...  
Keyword(s):  
Heart Disease ◽  
Protein Kinase ◽  
Exhaustive Exercise ◽  
Ampk Activation ◽  
Ischemic Disease ◽  
Specific Manner ◽  
Ampk Activity ◽  
Males And Females ◽  
Amp Activated Protein Kinase ◽  
The Impact

AbstractIschemic heart disease presents with significant differences between sexes. Endurance exercise protects the heart against ischemic disease and also distinctly impacts male and female patients through unidentified mechanisms, though some evidence implicates 5′-AMP-activated protein kinase (AMPK). The purpose of this investigation was to assess the impact of training and sex on cardiac AMPK activation following exhaustive exercise. AMPK activation was measured in trained and sedentary mice of both sexes. Trained mice ran on a treadmill at progressively increasing speeds and duration for 12 weeks. Trained and sedentary mice of both sexes were euthanized immediately following exhaustive exercise and compared to sedentary controls. Endurance training elicited adaptations indicative of aerobic adaptation including higher max running velocities and cardiac hypertrophy with no differences between males and females. AMPK activity was higher in male compared to females, and trained exhibited higher AMPK activity compared to sedentary mice. In response to training, male mice activated AMPK more robustly than female mice. Chronic exercise training increases the ability to activate cardiac AMPK in response to exhaustive exercise in a sex-specific manner. Understanding the interaction between exercise and sex is vital for use of exercise as medicine for heart disease in both men and women.

scholarly journals Apigenin and Luteolin Regulate Autophagy by Targeting NRH-Quinone Oxidoreductase 2 in Liver Cells

Antioxidants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 776
Author(s):  
Elzbieta Janda ◽  
Concetta Martino ◽  
Concetta Riillo ◽  
Maddalena Parafati ◽  
Antonella Lascala ◽  
...  
Keyword(s):  
Potential Role ◽  
Autophagic Flux ◽  
Ampk Activation ◽  
Amp Kinase ◽  
Quinone Oxidoreductase ◽  
Ampk Phosphorylation ◽  
Autophagy Induction ◽  
Ampk Activity ◽  
Dietary Flavonoids

Dietary flavonoids stimulate autophagy and prevent liver dysfunction, but the upstream signaling pathways triggered by these compounds are not well understood. Certain polyphenols bind directly to NRH-quinone oxidoreductase 2 (NQO2) and inhibit its activity. NQO2 is highly expressed in the liver, where it participates in quinone metabolism, but recent evidence indicates that it may also play a role in the regulation of oxidative stress and autophagy. Here, we addressed a potential role of NQO2 in autophagy induction by flavonoids. The pro-autophagic activity of seven flavonoid aglycons correlated perfectly with their ability to inhibit NQO2 activity, and flavones such as apigenin and luteolin showed the strongest activity in all assays. The silencing of NQO2 strongly reduced flavone-induced autophagic flux, although it increased basal LC3-II levels in HepG2 cells. Both flavones induced AMP kinase (AMPK) activation, while its reduction by AMPK beta (PRKAB1) silencing inhibited flavone-induced autophagy. Interestingly, the depletion of NQO2 levels by siRNA increased the basal AMPK phosphorylation but abrogated its further increase by apigenin. Thus, NQO2 contributes to the negative regulation of AMPK activity and autophagy, while its targeting by flavones releases pro-autophagic signals. These findings imply that NQO2 works as a flavone receptor mediating autophagy and may contribute to other hepatic effects of flavonoids.

scholarly journals Glucose regulates AMP-activated protein kinase activity and gene expression in clonal, hypothalamic neurons expressing proopiomelanocortin: additive effects of leptin or insulin

2007 ◽  
Vol 192 (3) ◽  
pp. 605-614 ◽  
Author(s):  
Fang Cai ◽  
Armen V Gyulkhandanyan ◽  
Michael B Wheeler ◽  
Denise D Belsham
Keyword(s):  
Protein Kinase ◽  
Energy Homeostasis ◽  
Cell Model ◽  
Neuronal Cell ◽  
Cell Types ◽  
Glucose Sensing ◽  
Protein Kinase Activity ◽  
Energy Status ◽  
Ampk Activity ◽  
Amp Activated Protein Kinase

The mammalian hypothalamus comprises an array of phenotypically distinct cell types that interpret peripheral signals of energy status and, in turn, elicits an appropriate response to maintain energy homeostasis. We used a clonal representative hypothalamic cell model expressing proopiomelanocortin (POMC; N-43/5) to study changes in AMP-activated protein kinase (AMPK) activity and glucose responsiveness. We have demonstrated the presence of cellular machinery responsible for glucose sensing in the cell line, including glucokinase, glucose transporters, and appropriate ion channels. ATP-sensitive potassium channels were functional and responded to glucose. The N-43/5 POMC neurons may therefore be an appropriate cell model to study glucose-sensing mechanisms in the hypothalamus. In N-43/5 POMC neurons, increasing glucose concentrations decreased phospho-AMPK activity. As a relevant downstream effect, we found that POMC transcription increased with 2.8 and 16.7 mM glucose. Upon addition of leptin, with either no glucose or with 5 mM glucose, we found that leptin decreased AMPK activity in N-43/5 POMC neurons, but had no significant effect at 25 mM glucose, whereas insulin decreased AMPK activity at only 5 mM glucose. These results demonstrate that individual hypothalamic neuronal cell types, such as the POMC neuron, can have distinct responses to peripheral signals that relay energy status to the brain, and will therefore be activated uniquely to control neuroendocrine function.

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