1
|
Stanojević M, Djuricic N, Parezanovic M, Biorac M, Pathak D, Spasic S, Lopicic S, Kovacevic S, Nesovic Ostojic J. The Impact of Chronic Magnesium Deficiency on Excitable Tissues-Translational Aspects. Biol Trace Elem Res 2024:10.1007/s12011-024-04216-2. [PMID: 38709369 DOI: 10.1007/s12011-024-04216-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Accepted: 04/28/2024] [Indexed: 05/07/2024]
Abstract
Neuromuscular excitability is a vital body function, and Mg2+ is an essential regulatory cation for the function of excitable membranes. Loss of Mg2+ homeostasis disturbs fluxes of other cations across cell membranes, leading to pathophysiological electrogenesis, which can eventually cause vital threat to the patient. Chronic subclinical Mg2+ deficiency is an increasingly prevalent condition in the general population. It is associated with an elevated risk of cardiovascular, respiratory and neurological conditions and an increased mortality. Magnesium favours bronchodilation (by antagonizing Ca2+ channels on airway smooth muscle and inhibiting the release of endogenous bronchoconstrictors). Magnesium exerts antihypertensive effects by reducing peripheral vascular resistance (increasing endothelial NO and PgI2 release and inhibiting Ca2+ influx into vascular smooth muscle). Magnesium deficiency disturbs heart impulse generation and propagation by prolonging cell depolarization (due to Na+/K+ pump and Kir channel dysfunction) and dysregulating cardiac gap junctions, causing arrhythmias, while prolonged diastolic Ca2+ release (through leaky RyRs) disturbs cardiac excitation-contraction coupling, compromising diastolic relaxation and systolic contraction. In the brain, Mg2+ regulates the function of ion channels and neurotransmitters (blocks voltage-gated Ca2+ channel-mediated transmitter release, antagonizes NMDARs, activates GABAARs, suppresses nAChR ion current and modulates gap junction channels) and blocks ACh release at neuromuscular junctions. Magnesium exerts multiple therapeutic neuroactive effects (antiepileptic, antimigraine, analgesic, neuroprotective, antidepressant, anxiolytic, etc.). This review focuses on the effects of Mg2+ on excitable tissues in health and disease. As a natural membrane stabilizer, Mg2+ opposes the development of many conditions of hyperexcitability. Its beneficial recompensation and supplementation help treat hyperexcitability and should therefore be considered wherever needed.
Collapse
Affiliation(s)
- Marija Stanojević
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia.
| | - Nadezda Djuricic
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| | - Miro Parezanovic
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
- Institute for Mother and Child Healthcare of Serbia "Dr Vukan Čupić", Belgrade, Serbia
| | - Marko Biorac
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| | - Dhruba Pathak
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| | - Svetolik Spasic
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| | - Srdjan Lopicic
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| | - Sanjin Kovacevic
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| | - Jelena Nesovic Ostojic
- University of Belgrade, Faculty of Medicine, Institute for Pathological Physiology "Ljubodrag Buba Mihailović", 9, Dr Subotića Street, 11000, Belgrade, Serbia
| |
Collapse
|
2
|
Liu CM, Lin FJ, Chen YC, Lin YK, Lu YY, Chan CS, Higa S, Chen SA, Chen YJ. Modulation of post-pacing action potential duration and contractile responses on ventricular arrhythmogenesis in chloroquine-induced long QT syndrome. Eur J Pharmacol 2023; 941:175493. [PMID: 36621600 DOI: 10.1016/j.ejphar.2023.175493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 12/18/2022] [Accepted: 01/04/2023] [Indexed: 01/07/2023]
Abstract
BACKGROUND Excitation-contraction (E-C) coupling, the interaction of action potential duration (APD) and contractility, plays an essential role in arrhythmogenesis. We aimed to investigate the arrhythmogenic role of E-C coupling in the right ventricular outflow tract (RVOT) in the chloroquine-induced long QT syndrome. METHODS Conventional microelectrodes were used to record electrical and mechanical activity simultaneously under electrical pacing (cycle lengths from 1000-100 ms) in rabbit RVOT tissue preparations before and after chloroquine with and without azithromycin. KB-R7943 (a Na+-Ca2+ exchanger [NCX] inhibitor), ranolazine (a late sodium current inhibitor), or MgSO4 were used to assess their pharmacological responses in the chloroquine-induced long QT syndrome. RESULTS Sequential infusion of chloroquine and chloroquine plus azithromycin triggered ventricular tachycardia (VT) (33.7%) after rapid pacing compared to baseline (6.7%, p = 0.004). There were greater post-pacing increases of the first occurrence of contractility (ΔContractility) in the VT group (VT vs. non-VT: 521.2 ± 50.5% vs. 306.5 ± 26.8%, p < 0.001). There was no difference in the first occurrence of action potential at 90% repolarization (ΔAPD90) (VT vs. non-VT: 49.7 ± 7.4 ms vs. 51.8 ± 13.1 ms, p = 0.914). Pacing-induced VT could be suppressed to baseline levels by KB-R7943 or MgSO4. Ranolazine did not suppress pacing-induced VT in chloroquine-treated RVOT. ΔContractility was reduced by KB-R7943 and MgSO4, but not by ranolazine. CONCLUSION ΔContractility (but not ΔAPD) played a crucial role in the genesis of pacing-induced VT in the long QT tissue model, which can be modulated by NCX (but not late sodium current) inhibition or MgSO4.
Collapse
Affiliation(s)
- Chih-Min Liu
- Heart Rhythm Center, Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan; Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Fong-Jhih Lin
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Biomedical Engineering, National Defense Medical Center, Taipei, Taiwan
| | - Yao-Chang Chen
- Department of Biomedical Engineering, National Defense Medical Center, Taipei, Taiwan
| | - Yung-Kuo Lin
- Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan; Division of Cardiology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Yen-Yu Lu
- Division of Cardiology, Sijhih Cathay General Hospital, New Taipei City, Taiwan
| | - Chao-Shun Chan
- Division of Cardiology, Department of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Satoshi Higa
- Cardiac Electrophysiology and Pacing Laboratory, Division of Cardiovascular Medicine, Makiminato Central Hospital, Okinawa, Japan
| | - Shih-Ann Chen
- Heart Rhythm Center, Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan; Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan; Cardiovascular Center, Taichung Veterans General Hospital, Taichung, Taiwan; National Chung Hsing University, Taichung, Taiwan
| | - Yi-Jen Chen
- Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan; Division of Cardiovascular Medicine, Department of Internal Medicine, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan; Cardiovascular Research Center, Wan-Fang Hospital, Taipei Medical University, Taipei, Taiwan.
| |
Collapse
|
3
|
Negru AG, Pastorcici A, Crisan S, Cismaru G, Popescu FG, Luca CT. The Role of Hypomagnesemia in Cardiac Arrhythmias: A Clinical Perspective. Biomedicines 2022; 10:2356. [PMID: 36289616 PMCID: PMC9598104 DOI: 10.3390/biomedicines10102356] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 09/03/2022] [Accepted: 09/09/2022] [Indexed: 11/17/2022] Open
Abstract
The importance of magnesium (Mg2+), a micronutrient implicated in maintaining and establishing a normal heart rhythm, is still controversial. It is known that magnesium is the cofactor of 600 and the activator of another 200 enzymatic reactions in the human organism. Hypomagnesemia can be linked to many factors, causing disturbances in energy metabolism, ion channel exchanges, action potential alteration and myocardial cell instability, all mostly leading to ventricular arrhythmia. This review article focuses on identifying evidence-based implications of Mg2+ in cardiac arrhythmias. The main identified benefits of magnesemia correction are linked to controlling ventricular response in atrial fibrillation, decreasing the recurrence of ventricular ectopies and stopping episodes of the particular form of ventricular arrhythmia called torsade de pointes. Magnesium has also been described to have beneficial effects on the incidence of polymorphic ventricular tachycardia and supraventricular tachycardia. The implication of hypomagnesemia in the genesis of atrial fibrillation is well established; however, even if magnesium supplementation for rhythm control, cardioversion facility or cardioversion success/recurrence of AF after cardiac surgery and rate control during AF showed some benefit, it remains controversial. Although small randomised clinical trials showed a reduction in mortality when magnesium was administered to patients with acute myocardial infarction, the large randomised clinical trials failed to show any benefit of the administration of intravenous magnesium over placebo.
Collapse
Affiliation(s)
- Alina Gabriela Negru
- Department of Cardiology, “Victor Babeş” University of Medicine and Pharmacy, 300041 Timisoara, Romania
- Department of Cardiology, Institute of Cardiovascular Diseases, 300310 Timisoara, Romania
| | | | - Simina Crisan
- Department of Cardiology, “Victor Babeş” University of Medicine and Pharmacy, 300041 Timisoara, Romania
- Department of Cardiology, Institute of Cardiovascular Diseases, 300310 Timisoara, Romania
| | - Gabriel Cismaru
- Department of Internal Medicine, Cardiology-Rehabilitation, ‘Iuliu Haţieganu’ University of Medicine and Pharmacy, 400347 Cluj-Napoca, Romania
| | - Florina Georgeta Popescu
- Department of Occupational Health, Victor Babeş University of Medicine and Pharmacy, 300041 Timisoara, Romania
| | - Constantin Tudor Luca
- Department of Cardiology, “Victor Babeş” University of Medicine and Pharmacy, 300041 Timisoara, Romania
- Department of Cardiology, Institute of Cardiovascular Diseases, 300310 Timisoara, Romania
| |
Collapse
|
4
|
Forbes EM, Bakrania BA, Steane SE, Moritz KM, Lingwood BE, Eiby YA. Expression of TRPM6 and TRPM7 in the preterm piglet heart. Front Pediatr 2022; 10:891722. [PMID: 36081632 PMCID: PMC9445433 DOI: 10.3389/fped.2022.891722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 08/01/2022] [Indexed: 11/13/2022] Open
Abstract
Preterm infants are at increased risk of death and disability, and cardiovascular instability after birth is a contributing factor. Immaturity of calcium handling in the preterm heart may limit myocardial contractility and cardiac output. Two transmembrane cation channels, TRPM6 and TRPM7, may regulate intracellular cardiac calcium in the neonatal period. The aim of this study was to determine TRPM6 and TRPM7 mRNA expression in piglet hearts in late gestation, and the effects of sex, maternal glucocorticoids, and the transition to extrauterine life. Left and right ventricular tissue was collected at a range of gestational ages from cesarean delivered piglets at birth and at 6 h old. Additional groups included piglets exposed to maternal glucocorticoid treatment and spontaneously born term piglets at 12-24 h old. TRPM6 and TRPM7 mRNA expression was measured using RT-qPCR. Males had significantly lower TRPM7 expression in the left ventricle across all gestational ages compared to females. At term, both ventricles had higher TRPM7 expression at 6 h old than at birth. In preterm piglets, TRPM7 expression only increased postnatally in the right ventricle following maternal glucocorticoid exposure. At 12-24 h old, TRPM7 expression in both ventricles was lower than levels in 6 h old term Caesar piglets (113 days). Male preterm piglets may have immature myocardial Ca2+ handling and this could contribute to their poorer outcomes. Increased TRPM7 expression is the mature response to birth that is missing in preterm neonates. TRPM7 could serve as a novel target to improve cardiac function in preterm neonates.
Collapse
Affiliation(s)
- Elizabeth M Forbes
- Queensland Children's Hospital, Brisbane, QLD, Australia.,UQ Centre for Clinical Research and Perinatal Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Bhavisha A Bakrania
- UQ Centre for Clinical Research and Perinatal Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Sarah E Steane
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Karen M Moritz
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia.,Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Barbara E Lingwood
- UQ Centre for Clinical Research and Perinatal Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| | - Yvonne A Eiby
- UQ Centre for Clinical Research and Perinatal Research Centre, Faculty of Medicine, The University of Queensland, Brisbane, QLD, Australia
| |
Collapse
|
5
|
Correa S, Guerra-Torres XE, Waikar SS, Mc Causland FR. Serum Magnesium, Blood Pressure, and Risk of Hypertension and Chronic Kidney Disease Progression in the CRIC Study. Hypertension 2021; 78:1771-1780. [PMID: 34757763 DOI: 10.1161/hypertensionaha.121.17694] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
[Figure: see text].
Collapse
Affiliation(s)
- Simon Correa
- Department of Internal Medicine, Yale School of Medicine, New Haven, CT (S.C.).,Yale New Haven Hospital, CT (S.C.).,Division of Renal Medicine, Brigham and Women's Hospital. Boston, MA (S.C., F.R.M.C.).,Harvard Medical School, Boston, MA (S.C., F.R.M.C.)
| | - Xavier E Guerra-Torres
- Nephrology Section, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, Spain (X.E.G.-T.)
| | - Sushrut S Waikar
- Section of Nephrology, Department of Medicine, Boston University School of Medicine and Boston Medical Center, MA (S.S.W.)
| | - Finnian R Mc Causland
- Division of Renal Medicine, Brigham and Women's Hospital. Boston, MA (S.C., F.R.M.C.).,Harvard Medical School, Boston, MA (S.C., F.R.M.C.)
| |
Collapse
|
6
|
Ozturk N, Olgar Y, Aslan M, Ozdemir S. Effects of magnesium supplementation on electrophysiological remodeling of cardiac myocytes in L-NAME induced hypertensive rats. J Bioenerg Biomembr 2016; 48:425-36. [PMID: 27193439 DOI: 10.1007/s10863-016-9666-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 05/11/2016] [Indexed: 02/07/2023]
Abstract
Hypertension is one of the major risk factors of cardiac hypertrophy and magnesium deficiency is suggested to be a contributing factor in the progression of this complication. In this study, we aimed to investigate the relationship between intracellular free Mg(2+) levels and electrophysiological changes developed in the myocardium of L-NAME induced hypertensive rats. Hypertension was induced by administration of 40 mg/kg of L-NAME for 6 weeks, while magnesium treated rats fed with a diet supplemented with 1 g/kg of MgO for the same period. L-NAME administration for 6 weeks elicited a significant increase in blood pressure which was corrected with MgO treatment; thereby cardiac hypertrophy developing secondary to hypertension was prevented. Cytosolic free magnesium levels of ventricular myocytes were significantly decreased with hypertension and magnesium administration restored these changes. Hypertension significantly decreased the fractional shortening with slowing of shortening kinetics in left ventricular myocytes whereas magnesium treatment was capable of restoring hypertension-induced contractile dysfunction. Long-term magnesium treatment significantly restored the hypertension-induced prolongation in action potentials of ventricular myocytes and suppressed Ito and Iss currents. In contrast, hypertension dependent decrement in intracellular Mg(2+) level did not cause a significant change in L-type Ca(2+) currents, SR Ca(2+) content and NCX activity. Nevertheless, hypertension mediated increase in superoxide anion, hydrogen peroxide and protein oxidation mitigated with magnesium treatment. In conclusion, magnesium administration improves mechanical abnormalities observed in hypertensive rat ventricular myocytes due to reduced oxidative stress. It is likely that, changes in intracellular magnesium balance may contribute to the pathophysiology of chronic heart diseases.
Collapse
Affiliation(s)
- Nihal Ozturk
- Faculty of Medicine, Department of Biophysics, Akdeniz University, Antalya, Turkey
| | - Yusuf Olgar
- Faculty of Medicine, Department of Biophysics, Akdeniz University, Antalya, Turkey
| | - Mutay Aslan
- Faculty of Medicine, Department of Biochemistry, Akdeniz University, Antalya, Turkey
| | - Semir Ozdemir
- Faculty of Medicine, Department of Biophysics, Akdeniz University, Antalya, Turkey.
| |
Collapse
|
7
|
de Baaij JHF, Hoenderop JGJ, Bindels RJM. Magnesium in man: implications for health and disease. Physiol Rev 2015; 95:1-46. [PMID: 25540137 DOI: 10.1152/physrev.00012.2014] [Citation(s) in RCA: 886] [Impact Index Per Article: 98.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Magnesium (Mg(2+)) is an essential ion to the human body, playing an instrumental role in supporting and sustaining health and life. As the second most abundant intracellular cation after potassium, it is involved in over 600 enzymatic reactions including energy metabolism and protein synthesis. Although Mg(2+) availability has been proven to be disturbed during several clinical situations, serum Mg(2+) values are not generally determined in patients. This review aims to provide an overview of the function of Mg(2+) in human health and disease. In short, Mg(2+) plays an important physiological role particularly in the brain, heart, and skeletal muscles. Moreover, Mg(2+) supplementation has been shown to be beneficial in treatment of, among others, preeclampsia, migraine, depression, coronary artery disease, and asthma. Over the last decade, several hereditary forms of hypomagnesemia have been deciphered, including mutations in transient receptor potential melastatin type 6 (TRPM6), claudin 16, and cyclin M2 (CNNM2). Recently, mutations in Mg(2+) transporter 1 (MagT1) were linked to T-cell deficiency underlining the important role of Mg(2+) in cell viability. Moreover, hypomagnesemia can be the consequence of the use of certain types of drugs, such as diuretics, epidermal growth factor receptor inhibitors, calcineurin inhibitors, and proton pump inhibitors. This review provides an extensive and comprehensive overview of Mg(2+) research over the last few decades, focusing on the regulation of Mg(2+) homeostasis in the intestine, kidney, and bone and disturbances which may result in hypomagnesemia.
Collapse
Affiliation(s)
- Jeroen H F de Baaij
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| |
Collapse
|
8
|
Zhou L, Cortassa S, Wei AC, Aon MA, Winslow RL, O'Rourke B. Modeling cardiac action potential shortening driven by oxidative stress-induced mitochondrial oscillations in guinea pig cardiomyocytes. Biophys J 2009; 97:1843-52. [PMID: 19804714 DOI: 10.1016/j.bpj.2009.07.029] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 06/17/2009] [Accepted: 07/07/2009] [Indexed: 12/15/2022] Open
Abstract
Ischemia-induced shortening of the cardiac action potential and its heterogeneous recovery upon reperfusion are thought to set the stage for reentrant arrhythmias and sudden cardiac death. We have recently reported that the collapse of mitochondrial membrane potential (DeltaPsi(m)) through a mechanism triggered by reactive oxygen species (ROS), coupled to the opening of sarcolemmal ATP-sensitive potassium (K(ATP)) channels, contributes to electrical dysfunction during ischemia-reperfusion. Here we present a computational model of excitation-contraction coupling linked to mitochondrial bioenergetics that incorporates mitochondrial ROS-induced ROS release with coupling between the mitochondrial energy state and electrical excitability mediated by the sarcolemmal K(ATP) current (I(K,ATP)). Whole-cell model simulations demonstrate that increasing the fraction of oxygen diverted from the respiratory chain to ROS production triggers limit-cycle oscillations of DeltaPsi(m), redox potential, and mitochondrial respiration through the activation of a ROS-sensitive inner membrane anion channel. The periods of transient mitochondrial uncoupling decrease the cytosolic ATP/ADP ratio and activate I(K,ATP), consequently shortening the cellular action potential duration and ultimately suppressing electrical excitability. The model simulates emergent behavior observed in cardiomyocytes subjected to metabolic stress and provides a new tool for examining how alterations in mitochondrial oxidative phosphorylation will impact the electrophysiological, contractile, and Ca(2+) handling properties of the cardiac cell. Moreover, the model is an important step toward building multiscale models that will permit investigation of the role of spatiotemporal heterogeneity of mitochondrial metabolism in the mechanisms of arrhythmogenesis and contractile dysfunction in cardiac muscle.
Collapse
Affiliation(s)
- Lufang Zhou
- Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | | | | | | | | |
Collapse
|
9
|
Raghu K, Singh R, Prathapan A, Yadav GK. Modulation of haloperidol induced electrophysiological alterations on cardiac action potential by various risk factors and gender difference. Chem Biol Interact 2009; 180:454-9. [DOI: 10.1016/j.cbi.2009.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2008] [Revised: 05/01/2009] [Accepted: 05/01/2009] [Indexed: 11/30/2022]
|
10
|
Gusev K, Niggli E. Modulation of the local SR Ca2+ release by intracellular Mg2+ in cardiac myocytes. ACTA ACUST UNITED AC 2009; 132:721-30. [PMID: 19029377 PMCID: PMC2585859 DOI: 10.1085/jgp.200810119] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In cardiac muscle, Ca2+-induced Ca2+ release (CICR) from the sarcoplasmic reticulum (SR) defines the amplitude and time course of the Ca2+ transient. The global elevation of the intracellular Ca2+ concentration arises from the spatial and temporal summation of elementary Ca2+ release events, Ca2+ sparks. Ca2+ sparks represent the concerted opening of a group of ryanodine receptors (RYRs), which are under the control of several modulatory proteins and diffusible cytoplasmic factors (e.g., Ca2+, Mg2+, and ATP). Here, we examined by which mechanism the free intracellular Mg2+ ([Mg2+]free) affects various Ca2+ spark parameters in permeabilized mouse ventricular myocytes, such as spark frequency, duration, rise time, and full width, at half magnitude and half maximal duration. Varying the levels of free ATP and Mg2+ in specifically designed solutions allowed us to separate the inhibition of RYRs by Mg2+ from the possible activation by ATP and Mg2+-ATP via the adenine binding site of the channel. Changes in [Mg2+]free generally led to biphasic alterations of the Ca2+ spark frequency. For example, lowering [Mg2+]free resulted in an abrupt increase of spark frequency, which slowly recovered toward the initial level, presumably as a result of SR Ca2+ depletion. Fitting the Ca2+ spark inhibition by [Mg2+]free with a Hill equation revealed a Ki of 0.1 mM. In conclusion, our results support the notion that local Ca2+ release and Ca2+ sparks are modulated by Mg2+ in the intracellular environment. This seems to occur predominantly by hindering Ca2+-dependent activation of the RYRs through competitive Mg2+ occupancy of the high-affinity activation site of the channels. These findings help to characterize CICR in cardiac muscle under normal and pathological conditions, where the levels of Mg2+ and ATP can change.
Collapse
Affiliation(s)
- Konstantin Gusev
- Department of Physiology, University of Bern, 3012 Bern, Switzerland
| | | |
Collapse
|
11
|
Mubagwa K, Gwanyanya A, Zakharov S, Macianskiene R. Regulation of cation channels in cardiac and smooth muscle cells by intracellular magnesium. Arch Biochem Biophys 2007; 458:73-89. [PMID: 17123458 DOI: 10.1016/j.abb.2006.10.014] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Revised: 10/16/2006] [Accepted: 10/16/2006] [Indexed: 01/06/2023]
Abstract
Magnesium regulates various ion channels in many tissues, including those of the cardiovascular system. General mechanisms by which intracellular Mg(2+) (Mg(i)(2+)) regulates channels are presented. These involve either a direct interaction with the channel, or an indirect modification of channel function via other proteins, such as enzymes or G proteins, or via membrane surface charges and phospholipids. To provide an insight into the role of Mg(i)(2+) in the cardiovascular system, effects of Mg(i)(2+) on major channels in cardiac and smooth muscle cells and the underlying mechanisms are then reviewed. Although Mg(i)(2+) concentrations are known to be stable, conditions under which they may change exist, such as following stimulation of beta-adrenergic receptors and of insulin receptors, or during pathophysiological conditions such as ischemia, heart failure or hypertension. Modifications of cardiovascular electrical or mechanical function, possibly resulting in arrhythmias or hypertension, may result from such changes of Mg(i)(2+) and their effects on cation channels.
Collapse
Affiliation(s)
- Kanigula Mubagwa
- Division of Experimental Cardiac Surgery, Department of Heart and Vessel Diseases, Katholieke Universiteit Leuven, Campus Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium.
| | | | | | | |
Collapse
|
12
|
McBride BF, Min B, Kluger J, Guertin D, Henyan NN, Coleman CI, Silver BB, White CM. An evaluation of the impact of oral magnesium lactate on the corrected QT interval of patients receiving sotalol or dofetilide to prevent atrial or ventricular tachyarrhythmia recurrence. Ann Noninvasive Electrocardiol 2006; 11:163-9. [PMID: 16630091 PMCID: PMC7313317 DOI: 10.1111/j.1542-474x.2006.00098.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Intravenous magnesium reduces the QTc interval of patients receiving ibutilide. Whether oral magnesium can reduce the QTc interval associated with oral sotalol and dofetilide is not known. This study was undertaken to evaluate the impact of oral magnesium on the QTc interval and whether an inherent intracellular magnesium deficiency exists among patients with arrhythmias. METHODS Participants receiving sotalol or dofetilide for atrial or ventricular arrhythmias were randomized to receive magnesium l-lactate (504 mg elemental magnesium daily, Niche Pharmaceuticals, Roanoke, TX) or placebo for 48 hours. A 12-lead electrocardiogram (ECG) was obtained at baseline, 3 hours, and 51 hours after dosing to correspond to the Tmax after oral ingestion. The QTc interval was measured from the ECGs and compared between groups. Intracellular magnesium concentrations were determined by energy-dispersive x-ray analysis at baseline and 51 hours after dosing (Intracellular Diagnostics, Inc., Foster City, CA). RESULTS The QTc interval reductions from baseline were greater in the magnesium group than placebo at 3 and 51 hours (P = 0.015 and P < 0.001, respectively). Sixty-three percent of patients (regardless of experimental group) had baseline intracellular magnesium concentrations below the normal reference range of 33.9-41.9 mEq/IU, with an average level of 32.6 +/- 2.2 mEq/IU. CONCLUSIONS Oral magnesium l-lactate raises intracellular magnesium concentrations and lowers the QTc interval of patients receiving sotalol or dofetilide.
Collapse
Affiliation(s)
- Brian F. McBride
- School of Pharmacy, University of Connecticut, Storrs, CT
- Drug Information, Hartford Hospital, Hartford, CT
| | - Bokyung Min
- School of Pharmacy, University of Connecticut, Storrs, CT
- Drug Information, Hartford Hospital, Hartford, CT
| | - Jeffrey Kluger
- School of Medicine, University of Connecticut, Farmington, CT
- Divisions of Cardiology
| | | | - Nickole N. Henyan
- School of Pharmacy, University of Connecticut, Storrs, CT
- Drug Information, Hartford Hospital, Hartford, CT
| | - Craig I. Coleman
- School of Pharmacy, University of Connecticut, Storrs, CT
- Drug Information, Hartford Hospital, Hartford, CT
| | | | - C. Michael White
- School of Pharmacy, University of Connecticut, Storrs, CT
- Drug Information, Hartford Hospital, Hartford, CT
| |
Collapse
|
13
|
McCulloch AD. Functionally and structurally integrated computational modeling of ventricular physiology. ACTA ACUST UNITED AC 2005; 54:531-9. [PMID: 15760485 DOI: 10.2170/jjphysiol.54.531] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Computational biology is integrative in several ways. Functionally, computational models are valuable for integrating the many interacting processes within biochemical networks and the many interacting physiological subsystems within the cell. Structurally detailed models provide a way of integrating across scales of biological organization from molecule to organism. Data integration across diverse laboratory and clinical measurements is another unique strength of computational biology. We describe examples of all three categories of integration by using recent advances in modeling cardiac excitation-contraction coupling and whole-heart electromechanics in health and disease.
Collapse
Affiliation(s)
- Andrew D McCulloch
- Department of Bioengineering, Whitaker Institute for Biomedical Engineering, University of California San Diego, La Jolla, CA 92093-0412, USA.
| |
Collapse
|
14
|
Michailova A, Saucerman J, Belik ME, McCulloch AD. Modeling regulation of cardiac KATP and L-type Ca2+ currents by ATP, ADP, and Mg2+. Biophys J 2005; 88:2234-49. [PMID: 15738467 PMCID: PMC1305273 DOI: 10.1529/biophysj.104.046284] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Changes in cytosolic free Mg(2+) and adenosine nucleotide phosphates affect cardiac excitability and contractility. To investigate how modulation by Mg(2+), ATP, and ADP of K(ATP) and L-type Ca(2+) channels influences excitation-contraction coupling, we incorporated equations for intracellular ATP and MgADP regulation of the K(ATP) current and MgATP regulation of the L-type Ca(2+) current in an ionic-metabolic model of the canine ventricular myocyte. The new model: 1), quantitatively reproduces a dose-response relationship for the effects of changes in ATP on K(ATP) current, 2), simulates effects of ADP in modulating ATP sensitivity of K(ATP) channel, 3), predicts activation of Ca(2+) current during rapid increase in MgATP, and 4), demonstrates that decreased ATP/ADP ratio with normal total Mg(2+) or increased free Mg(2+) with normal ATP and ADP activate K(ATP) current, shorten action potential, and alter ionic currents and intracellular Ca(2+) signals. The model predictions are in agreement with experimental data measured under normal and a variety of pathological conditions.
Collapse
Affiliation(s)
- Anushka Michailova
- Department of Bioengineering, University of California San Diego, La Jolla, CA 92093, USA.
| | | | | | | |
Collapse
|