AMP-activated protein kinase influences metabolic remodeling in H9c2 cells hypertrophied by arginine vasopressin

Substrate use switches from fatty acids toward glucose in pressure overload-induced cardiac hypertrophy with an acceleration of glycolysis being characteristic. The activation of AMP-activated protein kinase (AMPK) observed in hypertrophied hearts provides one potential mechanism for the acceleration of glycolysis. Here, we directly tested the hypothesis that AMPK causes the acceleration of glycolysis in hypertrophied heart muscle cells. The H9c2 cell line, derived from the embryonic rat heart, was treated with arginine vasopressin (AVP; 1 μM) to induce a cellular model of hypertrophy. Rates of glycolysis and oxidation of glucose and palmitate were measured in nonhypertrophied and hypertrophied H9c2 cells, and the effects of inhibition of AMPK were determined. AMPK activity was inhibited by 6-[4-(2-piperidin-1- yl-ethoxy)-phenyl]-3-pyridin-4-yl-pyrrazolo-[1,5-a]pyrimidine (compound C) or by adenovirus-mediated transfer of dominant negative AMPK. Compared with nonhypertrophied cells, glycolysis was accelerated and palmitate oxidation was reduced with no significant alteration in glucose oxidation in hypertrophied cells, a metabolic profile similar to that of intact hypertrophied hearts. Inhibition of AMPK resulted in the partial reduction of glycolysis in AVP-treated hypertrophied H9c2 cells. Acute exposure of H9c2 cells to AVP also activated AMPK and accelerated glycolysis. These elevated rates of glycolysis were not altered by AMPK inhibition but were blocked by agents that interfere with Ca2+ signaling, including extracellular EGTA, dantrolene, and 2-aminoethoxydiphenyl borate. We conclude that the acceleration of glycolysis in AVP-treated hypertrophied heart muscle cells is partially dependent on AMPK, whereas the acute glycolytic effects of AVP are AMPK independent and at least partially Ca2+ dependent.

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HYPERTROPHY OF THE HUMAN HEART AT THE LEVEL OF FINE STRUCTURE

The Journal of Cell Biology ◽

10.1083/jcb.18.1.195 ◽

1963 ◽

Vol 18 (1) ◽

pp. 195-206 ◽

Cited By ~ 65

Author(s):

G. W. Richter ◽

A. Kellner

Keyword(s):

Electron Microscopy ◽

Heart Muscle ◽

Light And Electron Microscopy ◽

Muscle Cells ◽

Left Ventricular ◽

Cross Sectional ◽

Size Frequency Distribution ◽

Hypertrophied Heart ◽

Significant Difference ◽

Heart Muscle Cells

Muscle cells in the left ventricular walls of four markedly hypertrophied human hearts (above 600 gm) were compared with muscle cells in four non-hypertrophied hearts (up to 310 gm). Blocks of tissue obtained postmortem within 6 hours were processed for light and electron microscopy under conditions suitable for good preservation of myofibrils. A lattice parameter, qh, was defined as the number of myosin filaments per square micron in either H zones or A bands. By the use of methods of electron microscopy, qh was determined for perpendicular cross-sections of A bands in a large number of well preserved myofibrils of muscle cells in both groups of hearts. Statistical evaluation of the distributions of values of qh revealed no significant difference between the two groups. Thus, the myofilament lattices in hypertrophied cells were geometrically within normal limits. Planimetric measurements of cross-sectional areas of muscle fibers were made, using photomicrographs obtained from one representative hypertrophied heart and from one control. The size-frequency distribution of the measurements showed a marked difference between the two hearts, and confirmed the presence of hypertrophy of muscle cells. Counts of the number of myofibrils per muscle cell were determined for samples from the same two hearts, evaluated statistically, and found to be significantly higher for the hypertrophied heart. It is proposed (a) that myofibrils in hypertrophied heart muscle cells have filament lattices with geometrical arrangement and macromolecular parameters that are the same as those found in myofibrils of normal heart muscle cells; and (b) that in hypertrophy the number of myofilaments increases through formation of new myofibrils, and possibly also by addition of filaments to preexisting myofibrils.

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Metabolic actions of metformin in the heart can occur by AMPK-independent mechanisms

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00873.2007 ◽

2008 ◽

Vol 294 (6) ◽

pp. H2497-H2506 ◽

Cited By ~ 61

Author(s):

Ramesh Saeedi ◽

Hannah L. Parsons ◽

Richard B. Wambolt ◽

Kim Paulson ◽

Vijay Sharma ◽

...

Keyword(s):

Fatty Acid ◽

Protein Kinase ◽

Fatty Acid Oxidation ◽

P38 Mapk ◽

Heart Muscle ◽

Glucose Utilization ◽

Acid Oxidation ◽

H9c2 Cells ◽

Compound C ◽

Ampk Activity

The metabolic actions of the antidiabetic agent metformin reportedly occur via the activation of the AMP-activated protein kinase (AMPK) in the heart and other tissues in the presence or absence of changes in cellular energy status. In this study, we tested the hypothesis that metformin has AMPK-independent effects on metabolism in heart muscle. Fatty acid oxidation and glucose utilization (glycolysis and glucose uptake) were measured in isolated working hearts from halothane-anesthetized male Sprague-Dawley rats and in cultured heart-derived H9c2 cells in the absence or in the presence of metformin (2 mM). Fatty acid oxidation and glucose utilization were significantly altered by metformin in hearts and H9c2 cells. AMPK activity was not measurably altered by metformin in either model system, and no impairment of energetic state was observed in the intact hearts. Furthermore, the inhibition of AMPK by 6-[4-(2-piperidin-1-yl-ethoxy)-phenyl]-3-pyridin-4-yl-pyyrazolo[1,5-a] pyrimidine (Compound C), a well-recognized pharmacological inhibitor of AMPK, or the overexpression of a dominant-negative form of AMPK failed to prevent the metabolic actions of metformin in H9c2 cells. The exposure of H9c2 cells to inhibitors of p38 mitogen-activated protein kinase (p38 MAPK) or protein kinase C (PKC) partially or completely abrogated metformin-induced alterations in metabolism in these cells, respectively. Thus the metabolic actions of metformin in the heart muscle can occur independent of changes in AMPK activity and may be mediated by p38 MAPK- and PKC-dependent mechanisms.

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Early heart muscle cells identified

Nature ◽

10.1038/news.2009.522 ◽

2009 ◽

Author(s):

Jane Qiu

Keyword(s):

Heart Muscle ◽

Muscle Cells ◽

Heart Muscle Cells

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Unravelling the ultrastructural details of αT‐catenin‐deficient cell–cell contacts between heart muscle cells by the use of FIB‐SEM

Journal of Microscopy ◽

10.1111/jmi.12855 ◽

2019 ◽

Vol 279 (3) ◽

pp. 189-196 ◽

Cited By ~ 1

Author(s):

B. VANSLEMBROUCK ◽

A. KREMER ◽

F. VAN ROY ◽

S. LIPPENS ◽

J. VAN HENGEL

Keyword(s):

Heart Muscle ◽

Muscle Cells ◽

Cell Contacts ◽

Deficient Cell ◽

Heart Muscle Cells ◽

Cell Cell

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Adrenaline is a critical mediator of acute exercise-induced AMP-activated protein kinase activation in adipocytes

Biochemical Journal ◽

10.1042/bj20061479 ◽

2007 ◽

Vol 403 (3) ◽

pp. 473-481 ◽

Cited By ~ 81

Author(s):

Ho-Jin Koh ◽

Michael F. Hirshman ◽

Huamei He ◽

Yangfeng Li ◽

Yasuko Manabe ◽

...

Keyword(s):

Protein Kinase ◽

Protein Kinase Activity ◽

Chronic Exercise ◽

Rat Adipocytes ◽

Compound C ◽

Isolated Adipocytes ◽

Ampk Activity ◽

Exercise Induced ◽

Amp Activated Protein Kinase

Exercise increases AMPK (AMP-activated protein kinase) activity in human and rat adipocytes, but the underlying molecular mechanisms and functional consequences of this activation are not known. Since adrenaline (epinephrine) concentrations increase with exercise, in the present study we hypothesized that adrenaline activates AMPK in adipocytes. We show that a single bout of exercise increases AMPKα1 and α2 activities and ACC (acetyl-CoA carboxylase) Ser79 phosphorylation in rat adipocytes. Similarly to exercise, adrenaline treatment in vivo increased AMPK activities and ACC phosphorylation. Pre-treatment of rats with the β-blocker propranolol fully blocked exercise-induced AMPK activation. Increased AMPK activity with exercise and adrenaline treatment in vivo was accompanied by an increased AMP/ATP ratio. Adrenaline incubation of isolated adipocytes also increased the AMP/ATP ratio and AMPK activities, an effect blocked by propranolol. Adrenaline incubation increased lipolysis in isolated adipocytes, and Compound C, an AMPK inhibitor, attenuated this effect. Finally, a potential role for AMPK in the decreased adiposity associated with chronic exercise was suggested by marked increases in AMPKα1 and α2 activities in adipocytes from rats trained for 6 weeks. In conclusion, both acute and chronic exercise are significant regulators of AMPK activity in rat adipocytes. Our findings suggest that adrenaline plays a critical role in exercise-stimulated AMPKα1 and α2 activities in adipocytes, and that AMPK can function in the regulation of lipolysis.

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Effect of pentobarbital on sodium permeability of heart muscle cells

Bulletin of Experimental Biology and Medicine ◽

10.1007/bf01262473 ◽

1984 ◽

Vol 98 (2) ◽

pp. 1088-1091

Author(s):

N. V. Dmitrieva ◽

E. I. Shtresgeim ◽

N. A. Burnashev ◽

V. V. Chernokhvostov

Keyword(s):

Heart Muscle ◽

Muscle Cells ◽

Sodium Permeability ◽

Heart Muscle Cells

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Enzymatic digestion and urea extraction on leptomeric structures and normomeric myofibrils in heart muscle cells

Journal of Ultrastructure Research ◽

10.1016/s0022-5320(76)80070-6 ◽

1976 ◽

Vol 55 (2) ◽

pp. 245-256 ◽

Cited By ~ 4

Author(s):

Gottfried Bogusch

Keyword(s):

Heart Muscle ◽

Muscle Cells ◽

Enzymatic Digestion ◽

Heart Muscle Cells

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Abstract 337: Activation of Myocardial AMP-activated Protein Kinase by Metformin Prevents Progression of Heart Failure in Dogs; Involvement of eNOS Activation

Circulation ◽

10.1161/circ.118.suppl_18.s_286-c ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Hideyuki Sasaki ◽

Hiroshi Asanuma ◽

Masashi Fujita ◽

Hiroyuki Takahama ◽

Masanori Asakura ◽

...

Keyword(s):

Oxidative Stress ◽

Nitric Oxide ◽

Heart Failure ◽

Cell Death ◽

Protein Kinase ◽

Left Ventricular ◽

Vehicle Group ◽

Mrna Levels ◽

Compound C ◽

Amp Activated Protein Kinase

Background; Several studies have shown that metformin activates AMP-activated protein kinase (AMPK), which mediates potent cardioprotection against ischemia-reperfusion injury. AMPK is also activated in experimental failing myocardium, suggesting that activation of AMPK is beneficial for the pathophysiology of heart failure. We investigated whether metformin prevents oxidative stress-induced cell death in rat cardiomyocytes and attenuates the progression of heart failure in dogs. Methods and Results; The treatment with metformin (10 μmol/L) protected the rat cultured cardiomyocytes against cell death due to H 2 O 2 exposure (50 μmol/L) as indicated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), TUNEL staining, and flow cytometry. These effects were blunted by an AMPK inhibitor, compound-C (20 μmol/L), suggesting that the activation of AMPK decreased the extent of apoptosis-induced cell death due to H 2 O 2 exposure. Continuous rapid ventricular pacing (230/min for 4 weeks) in dogs caused heart failure and the treatment with metformin (100 mg/kg/day PO, n=8) decreased left ventricular (LV) end-diastolic dimension (32.8±0.4 vs. 36.5±1.0 mm, p< 0.01) and pressure (11.8±1.1 vs. 22±0.9 mmHg, p< 0.01), and increased LV fractional shortening (18.6±1.8 vs. 9.6±0.7 %, p< 0.01) along with enhanced phosphorylation of AMPK and the decreased the number of TUNEL-positive cells of the LV myocardium compared with the vehicle group (n=8). Interestingly, metformin increased the protein and mRNA levels of endothelial nitric oxide synthase of the LV myocardium and plasma nitric oxide levels. Metformin improved the plasma insulin resistance without increased myocardial GLUT-4 translocation. Furthermore, the subcutaneous administration of AICAR (50 mg/kg/every other day), another AMPK activator mediated the equivalent effects to metformin, strengthening the pivotal role of AMPK in reduction of apoptosis and prevention of heart failure. Conclusions; Activation of myocardial AMPK attenuated the oxidative stress-induced cardiomyocyte apoptosis and prevented the progression of heart failure in dogs, along with eNOS activation. Thus, metformin or AICAR may be applicable as a novel therapy for heart failure.

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Characteristics of active Na transport in intact cardiac cells

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1979.236.2.h189 ◽

1979 ◽

Vol 236 (2) ◽

pp. H189-H199 ◽

Cited By ~ 2

Author(s):

H. G. Glitsch

Keyword(s):

Heart Muscle ◽

Muscle Cells ◽

Cardiac Cells ◽

Na Transport ◽

Concentration Gradients ◽

Experimental Conditions ◽

Na Pump ◽

Na Efflux ◽

Heart Muscle Cells ◽

K Concentration

An active Na transport maintains the Na and K concentration gradients across the cell membrane of many cells and restores them following excitation. Heart muscle cells display frequent electrical discharges and thus the cardiac Na pump is of fundamental functional significance. Some methods for studying active Na transport are described. The active Na efflux from heart muscle cells is activated by an increase in the intracellular Na and the extracellular K concentration. The linkage between active Na efflux and active K influx varies widely according to the experimental conditions. The cardiac Na pump is electrogenic and can contribute directly to the membrane potential of the cells. The effects of active Na transport on contraction and intercellular coupling in myocardium are discussed.

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