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Iqbal SM, Lemmens‐Gruber R. Phosphorylation of cardiac voltage-gated sodium channel: Potential players with multiple dimensions. Acta Physiol (Oxf) 2019; 225:e13210. [PMID: 30362642 PMCID: PMC6590314 DOI: 10.1111/apha.13210] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 10/14/2018] [Accepted: 10/14/2018] [Indexed: 12/11/2022]
Abstract
Cardiomyocytes are highly coordinated cells with multiple proteins organized in micro domains. Minor changes or interference in subcellular proteins can cause major disturbances in physiology. The cardiac sodium channel (NaV1.5) is an important determinant of correct electrical activity in cardiomyocytes which are localized at intercalated discs, T‐tubules and lateral membranes in the form of a macromolecular complex with multiple interacting protein partners. The channel is tightly regulated by post‐translational modifications for smooth conduction and propagation of action potentials. Among regulatory mechanisms, phosphorylation is an enzymatic and reversible process which modulates NaV1.5 channel function by attaching phosphate groups to serine, threonine or tyrosine residues. Phosphorylation of NaV1.5 is implicated in both normal physiological and pathological processes and is carried out by multiple kinases. In this review, we discuss and summarize recent literature about the (a) structure of NaV1.5 channel, (b) formation and subcellular localization of NaV1.5 channel macromolecular complex, (c) post‐translational phosphorylation and regulation of NaV1.5 channel, and (d) how these phosphorylation events of NaV1.5 channel alter the biophysical properties and affect the channel during disease status. We expect, by reviewing these aspects will greatly improve our understanding of NaV1.5 channel biology, physiology and pathology, which will also provide an insight into the mechanism of arrythmogenesis at molecular level.
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Affiliation(s)
- Shahid M. Iqbal
- Department of Pharmacology and Toxicology University of Vienna Vienna Austria
- Drugs Regulatory Authority of Pakistan Telecom Foundation (TF) Complex Islamabad Pakistan
| | - Rosa Lemmens‐Gruber
- Department of Pharmacology and Toxicology University of Vienna Vienna Austria
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Ramos-Franco J, Aguilar-Sanchez Y, Escobar AL. Intact Heart Loose Patch Photolysis Reveals Ionic Current Kinetics During Ventricular Action Potentials. Circ Res 2015; 118:203-15. [PMID: 26565013 DOI: 10.1161/circresaha.115.307399] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 11/12/2015] [Indexed: 12/16/2022]
Abstract
RATIONALE Assessing the underlying ionic currents during a triggered action potential (AP) in intact perfused hearts offers the opportunity to link molecular mechanisms with pathophysiological problems in cardiovascular research. The developed loose patch photolysis technique can provide striking new insights into cardiac function at the whole heart level during health and disease. OBJECTIVE To measure transmembrane ionic currents during an AP to determine how and when surface Ca(2+) influx that triggers Ca(2+)-induced Ca(2+) release occurs and how Ca(2+)-activated conductances can contribute to the genesis of AP phase 2. METHODS AND RESULTS Loose patch photolysis allows the measurement of transmembrane ionic currents in intact hearts. During a triggered AP, a voltage-dependent Ca(2+) conductance was fractionally activated (dis-inhibited) by rapidly photo-degrading nifedipine, the Ca(2+) channel blocker. The ionic currents during a mouse ventricular AP showed a fast early component and a slower late component. Pharmacological studies established that the molecular basis underlying the early component was driven by an influx of Ca(2+) through the L-type channel, CaV 1.2. The late component was identified as an Na(+)-Ca(2+) exchanger current mediated by Ca(2+) released from the sarcoplasmic reticulum. CONCLUSIONS The novel loose patch photolysis technique allowed the dissection of transmembrane ionic currents in the intact heart. We were able to determine that during an AP, L-type Ca(2+) current contributes to phase 1, whereas Na(+)-Ca(2+) exchanger contributes to phase 2. In addition, loose patch photolysis revealed that the influx of Ca(2+) through L-type Ca(2+) channels terminates because of voltage-dependent deactivation and not by Ca(2+)-dependent inactivation, as commonly believed.
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Affiliation(s)
- Josefina Ramos-Franco
- From the Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, IL (J.R.-F.); and Quantitative Systems Biology Program, School of Natural Sciences (Y.A.-S.) and Biological Engineering and Small Scale Technologies Program, School of Engineering (A.L.E.), University of California, Merced, CA
| | - Yuriana Aguilar-Sanchez
- From the Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, IL (J.R.-F.); and Quantitative Systems Biology Program, School of Natural Sciences (Y.A.-S.) and Biological Engineering and Small Scale Technologies Program, School of Engineering (A.L.E.), University of California, Merced, CA
| | - Ariel L Escobar
- From the Department of Molecular Biophysics and Physiology, Rush University Medical Center, Chicago, IL (J.R.-F.); and Quantitative Systems Biology Program, School of Natural Sciences (Y.A.-S.) and Biological Engineering and Small Scale Technologies Program, School of Engineering (A.L.E.), University of California, Merced, CA.
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Liu F, Wu B, Du Y, Wu Y, Chen H, Xia F, Jin Z, Xu X. Epinephrine reversed high-concentration bupivacaine- induced inhibition of calcium channels and transient outward potassium current channels, but not on sodium channel in ventricular myocytes of rats. BMC Anesthesiol 2015; 15:66. [PMID: 25924894 PMCID: PMC4422592 DOI: 10.1186/s12871-015-0049-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Accepted: 04/22/2015] [Indexed: 12/03/2022] Open
Abstract
Background Epinephrine is a first-line drug for cardiopulmonary resuscitation, but its efficacy in the treatment of bupivacaine-induced cardiac toxicity is still in question. We hypothesized that epinephrine can reverse cardiac inhibition of bupivacaine by modulating ion flows through the ventricular myocyte membrane channels of rats. The aim of this study was to observe and report the effects of epinephrine on high-concentration bupivacaine-induced inhibition of sodium (INa), L-type calcium (ICa-L), and transient outward potassium (Ito) currents in the ventricular myocytes of rats. Methods The ventricular myocytes were isolated from Sprague-Dawley rats (250-300 g) by acute enzymatic dissociation. The whole-cell patch clamp technique was used to record the ion channel currents in single ventricular myocytes both before and after administration of medications. Result Administration of bupivacaine 100 μmol/L significantly reduced INa, (P < 0.05). However, administration of bupivacaine 100 μmol/L in conjunction with epinephrine 0.15 μg/ml had no effect in restoring INa to its previous state. Similarly, a sharp decline of ICa-L and Ito was observed after administration of bupivacaine 100 μmol/L (P < 0.05). In contrast to INa, ICa-L and Ito were significantly improved after the administration of the aforementioned combination of bupivacaine and epinephrine (P < 0.05). Conclusion Epinephrine can reverse high-concentration bupivacaine induced inhibition of ICa-L and Ito, but not INa. Thus, epinephrine’s effectiveness in reversal of bupivacaine-induced cardiac toxicity secondary to sodium channel inhibition may be limited.
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Bondarenko VE. A compartmentalized mathematical model of the β1-adrenergic signaling system in mouse ventricular myocytes. PLoS One 2014; 9:e89113. [PMID: 24586529 PMCID: PMC3931689 DOI: 10.1371/journal.pone.0089113] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Accepted: 01/14/2014] [Indexed: 01/08/2023] Open
Abstract
The β1-adrenergic signaling system plays an important role in the functioning of cardiac cells. Experimental data shows that the activation of this system produces inotropy, lusitropy, and chronotropy in the heart, such as increased magnitude and relaxation rates of [Ca2+]i transients and contraction force, and increased heart rhythm. However, excessive stimulation of β1-adrenergic receptors leads to heart dysfunction and heart failure. In this paper, a comprehensive, experimentally based mathematical model of the β1-adrenergic signaling system for mouse ventricular myocytes is developed, which includes major subcellular functional compartments (caveolae, extracaveolae, and cytosol). The model describes biochemical reactions that occur during stimulation of β1-adrenoceptors, changes in ionic currents, and modifications of Ca2+ handling system. Simulations describe the dynamics of major signaling molecules, such as cyclic AMP and protein kinase A, in different subcellular compartments; the effects of inhibition of phosphodiesterases on cAMP production; kinetics and magnitudes of phosphorylation of ion channels, transporters, and Ca2+ handling proteins; modifications of action potential shape and duration; magnitudes and relaxation rates of [Ca2+]i transients; changes in intracellular and transmembrane Ca2+ fluxes; and [Na+]i fluxes and dynamics. The model elucidates complex interactions of ionic currents upon activation of β1-adrenoceptors at different stimulation frequencies, which ultimately lead to a relatively modest increase in action potential duration and significant increase in [Ca2+]i transients. In particular, the model includes two subpopulations of the L-type Ca2+ channels, in caveolae and extracaveolae compartments, and their effects on the action potential and [Ca2+]i transients are investigated. The presented model can be used by researchers for the interpretation of experimental data and for the developments of mathematical models for other species or for pathological conditions.
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Affiliation(s)
- Vladimir E. Bondarenko
- Department of Mathematics and Statistics and Neuroscience Institute, Georgia State University, Atlanta, Georgia, United States of America
- * E-mail:
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Viemari JC, Garcia AJ, Doi A, Elsen G, Ramirez JM. β-Noradrenergic receptor activation specifically modulates the generation of sighs in vivo and in vitro. Front Neural Circuits 2013; 7:179. [PMID: 24273495 PMCID: PMC3824105 DOI: 10.3389/fncir.2013.00179] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 10/23/2013] [Indexed: 11/13/2022] Open
Abstract
The pre-Bötzinger complex (preBötC), an area that is critical for generating breathing (eupnea), gasps and sighs is continuously modulated by catecholamines. These amines and the generation of sighs have also been implicated in the regulation of arousal. Here we studied the catecholaminergic modulation of sighs not only in anesthetized freely breathing mice (in vivo), but also in medullary slice preparations that contain the preBötC and that generate fictive eupneic and sigh rhythms in vitro. We demonstrate that activating β-noradrenergic receptors (β-NR) specifically increases the frequency of sighs, while eupnea remains unaffected both in vitro and in vivo. β-NR activation specifically increased the frequency of intrinsically bursting pacemaker neurons that rely on persistent sodium current (I(Nap)). By contrast, all parameters of bursting pacemakers that rely on the non-specific cation current (I(CAN)) remained unaffected. Moreover, riluzole, which blocks bursting in I(Nap) pacemakers abolished sighs altogether, while flufenamic acid (FFA) which blocks the I(CAN) current did not alter the sigh-increasing effect caused by β-NR. Our results suggest that the selective β-NR action of sighs may result from the modulation of I(Nap) pacemaker activity and that disturbances in noradrenergic system may contribute to abnormal arousal response. The β-NR action on the preBötC may be an important mechanism in modulating behaviors that are specifically associated with sighs, such as the regulation of the early events leading to the arousal response.
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Affiliation(s)
- Jean-Charles Viemari
- Team P3M, Institut de Neurosciences de la Timone, UMR 7289, CNRS, Aix Marseille Univesité , Marseille, France
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Grant AO. Basic Electrophysiology. Card Electrophysiol Clin 2010; 2:325-340. [PMID: 28770793 DOI: 10.1016/j.ccep.2010.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Available evidence suggests that the ion channels that generate the normal action potential are also the basis for the arrhythmias that occur in disease states. Therefore, a thorough understanding of the function of the ion channels that generate the action potential is an important foundation for understanding the bases of arrhythmias and their treatment. This need is made all the more pressing by the discoveries in molecular genetics and membrane biophysics that have elucidated the fundamental mechanisms of a broad range of cardiac arrhythmias.
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Affiliation(s)
- Augustus O Grant
- Cardiovascular Division, Duke University School of Medicine, Box 3504, Durham, NC, USA
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Affiliation(s)
- Augustus O Grant
- Cardiovascular Division, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA.
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Wang HW, Yang ZF, Zhang Y, Yang JM, Liu YM, Li CZ. Beta-receptor activation increases sodium current in guinea pig heart. Acta Pharmacol Sin 2009; 30:1115-22. [PMID: 19617895 DOI: 10.1038/aps.2009.96] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
AIM To study the influence of beta-receptor activation on sodium channel current and the physiological significance of increased sodium current with regard to the increased cardiac output caused by sympathetic excitation. METHODS Multiple experimental approaches, including ECG, action potential recording with conventional microelectrodes, whole-cell current measurements, single-channel recordings, and pumping-force measurements, were applied to guinea pig hearts and isolated ventricular myocytes. RESULTS Isoprenaline was found to dose-dependently shorten QRS waves, increase the amplitude and the V(max) of action potentials, augment the fast sodium current, and increase the occurrence frequencies and open time constants of the long-open and burst modes of the sodium channel. Increased levels of membrane-permeable cAMP have similar effects. In the presence of a calcium channel blocker, TTX reversed the increased pumping force produced by isoprenaline. CONCLUSION Beta-adrenergic modulation increases the inward sodium current and accelerates the conduction velocity within the ventricles by changing the sodium channel modes, which might both be conducive to the synchronous contraction of the heart and enhance its pumping function.
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Jansen MA, Shen H, Zhang L, Wolkowicz PE, Balschi JA. Energy requirements for the Na+ gradient in the oxygenated isolated heart: effect of changing the free energy of ATP hydrolysis. Am J Physiol Heart Circ Physiol 2003; 285:H2437-45. [PMID: 12958035 DOI: 10.1152/ajpheart.00534.2003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study tests the hypothesis that a decrease of the free energy of ATP hydrolysis (Delta GATP) below a threshold value will inhibit Na+-K+-ATPase (Na+ pump) activity and result in an increase of intracellular Na+ concentration ([Na+]i) in the heart. Conditions were designed in which hearts were solely dependent on ATP derived from oxidative phosphorylation. The only substrate supplied was the fatty acid butyrate (Bu) at either low, 0.1 mM (LowBu), or high, 4 mM (HighBu), concentrations. Escalating work demand reduced the Delta GATP of the LowBu hearts. 31P, 23Na, and 87Rb NMR spectroscopy measured high-energy phosphate metabolites, [Na+]i, and Rb+ uptake. Rb+ uptake was used to estimate Na+ pump activity. To measure [Na+]i using a shift reagent for cations, extracellular Ca2+ was reduced to 0.85 mM, which eliminated work demand Delta GATP reductions. Increasing extracellular Na+ (Nae+) to 200 mM restored work demand Delta GATP reductions. In response to higher [Na+]e, [Na+]i increased equally in LowBu and HighBu hearts to approximately 8.6 mM, but Delta GATP decreased only in LowBu hearts. At lowest work demand the LowBu heart Delta GATP was -53 kJ/mol, Rb+ uptake was similar to that of HighBu hearts, and [Na+]i was constant. At highest work demand the LowBu heart Delta GATP decreased to -48 kJ/mol, the [Na+]i increased to 25 mM, and Rb+ uptake was 56% of that in HighBu hearts. At the highest work demand the HighBu heart Delta GATP was -54 kJ/mol and [Na+]i increased only approximately 10%. We conclude that a Delta GATP below -50 kJ/mol limits the Na+ pump and prevents maintenance of [Na+]i homeostasis.
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Affiliation(s)
- Maurits A Jansen
- Division of Cardiovascular Disease, Department o fMedicine, Universityof Alabama, Birmingham, 35294-4470, USA
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Yarbrough TL, Lu T, Lee HC, Shibata EF. Localization of cardiac sodium channels in caveolin-rich membrane domains: regulation of sodium current amplitude. Circ Res 2002; 90:443-9. [PMID: 11884374 DOI: 10.1161/hh0402.105177] [Citation(s) in RCA: 147] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study demonstrates that caveolae, omega-shaped membrane invaginations, are involved in cardiac sodium channel regulation by a mechanism involving the alpha subunit of the stimulatory heterotrimeric G-protein, Galpha(s), via stimulation of the cell surface beta-adrenergic receptor. Stimulation of beta-adrenergic receptors with 10 micromol/L isoproterenol in the presence of a protein kinase A inhibitor increased the whole-cell sodium current by a "direct" cAMP-independent G-protein mechanism. The addition of antibodies against caveolin-3 to the cell's cytoplasm via the pipette solution abrogated this direct G protein-induced increase in sodium current, whereas antibodies to caveolin-1 or caveolin-2 did not. Voltage-gated sodium channel proteins were found to associate with caveolin-rich membranes obtained by detergent-free buoyant density separation. The purity of the caveolar membrane fraction was verified by Western blot analyses, which indicated that endoplasmic/sarcoplasmic reticulum, endosomal compartments, Golgi apparatus, clathrin-coated vesicles, and sarcolemmal membranes were excluded from the caveolin-rich membrane fraction. Additionally, the sodium channel was found to colocalize with caveolar membranes by immunoprecipitation, indirect immunofluorescence, and immunogold transmission electron microscopy. These results suggest that stimulation of beta-adrenergic receptors, and thereby Galpha(s), promotes the presentation of cardiac sodium channels associated with caveolar membranes to the sarcolemma.
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Affiliation(s)
- Tracy L Yarbrough
- Department of Physiology, University of Iowa College of Medicine, Iowa City, Iowa 52242-1109, USA
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Shimoni Y. Hormonal control of cardiac ion channels and transporters. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 1999; 72:67-108. [PMID: 10446502 DOI: 10.1016/s0079-6107(99)00005-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Y Shimoni
- Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, Alta., Canada.
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Kirstein M, Katzer A, Hu K, Gaudron P, Ertl G, Langenfeld H, Kochsiek K. Influence of cardiac dysfunction on fast sodium current regulation by Forskolin. Pacing Clin Electrophysiol 1996; 19:2018-22. [PMID: 8945089 DOI: 10.1111/j.1540-8159.1996.tb03273.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
There are several reports of an altered beta-adrenergic pathway in heart failure. Since the fast cardiac sodium current (INa+) is also subject to beta-receptor dependent regulation, we investigated its regulation in a model of cardiac dysfunction. Adenylyl cyclase was stimulated directly with forskolin as one step in the beta-adrenergic pathway. Twelve-week-old Wistar rats were infarcted by ligation of the left anterior descending coronary artery. Eight weeks later, the induced hemodynamic changes were evaluated. The left ventricular end-diastolic pressure (LVEDP) was used as a measure of the hemodynamic effects of the myocardial infarction. With the loose patch clamp technique, INa+ was measured in intact papillary muscles at an external sodium concentration of 150 mmol/L. Potential dependent availability was tested with pulses to 0 mV from various conditioning potentials. In animals with minor infarction (n = 7, LVEDP = 7.7 +/- 0.9 mmHg), forskolin (3 mumol/L) increased the maximal available INa+ to 109% +/- 13% of baseline values. This increase was nearly the same in the group with significant infarctions (n = 7, LVEDP = 15.7 +/- 1.6 mmHg) to 113% +/- 6%. Thus, although we previously observed a reduction of the isoproterenol induced increase of INa+ in rats with significant myocardial infarctions, this increase remains the same when adenylyl cyclase is stimulated directly. This is consistent with a direct beta-receptor down-regulation or desensitization.
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Affiliation(s)
- M Kirstein
- Medizinische Universitätsklinik, Würzburg, Germany
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