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Rudokas MW, McKay M, Toksoy Z, Eisen JN, Bögner M, Young LH, Akar FG. Mitochondrial network remodeling of the diabetic heart: implications to ischemia related cardiac dysfunction. Cardiovasc Diabetol 2024; 23:261. [PMID: 39026280 PMCID: PMC11264840 DOI: 10.1186/s12933-024-02357-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Accepted: 07/10/2024] [Indexed: 07/20/2024] Open
Abstract
Mitochondria play a central role in cellular energy metabolism, and their dysfunction is increasingly recognized as a critical factor in the pathogenesis of diabetes-related cardiac pathophysiology, including vulnerability to ischemic events that culminate in myocardial infarction on the one hand and ventricular arrhythmias on the other. In diabetes, hyperglycemia and altered metabolic substrates lead to excessive production of reactive oxygen species (ROS) by mitochondria, initiating a cascade of oxidative stress that damages mitochondrial DNA, proteins, and lipids. This mitochondrial injury compromises the efficiency of oxidative phosphorylation, leading to impaired ATP production. The resulting energy deficit and oxidative damage contribute to functional abnormalities in cardiac cells, placing the heart at an increased risk of electromechanical dysfunction and irreversible cell death in response to ischemic insults. While cardiac mitochondria are often considered to be relatively autonomous entities in their capacity to produce energy and ROS, their highly dynamic nature within an elaborate network of closely-coupled organelles that occupies 30-40% of the cardiomyocyte volume is fundamental to their ability to exert intricate regulation over global cardiac function. In this article, we review evidence linking the dynamic properties of the mitochondrial network to overall cardiac function and its response to injury. We then highlight select studies linking mitochondrial ultrastructural alterations driven by changes in mitochondrial fission, fusion and mitophagy in promoting cardiac ischemic injury to the diabetic heart.
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Affiliation(s)
- Michael W Rudokas
- Department of Internal Medicine, Section of Cardiovascular Medicine, Yale School of Medicine, New Haven, CT, USA
| | - Margaret McKay
- Department of Internal Medicine, Section of Cardiovascular Medicine, Yale School of Medicine, New Haven, CT, USA
- Department of Biomedical Engineering, Yale University Schools of Engineering and Applied Sciences, New Haven, CT, USA
| | - Zeren Toksoy
- Department of Internal Medicine, Section of Cardiovascular Medicine, Yale School of Medicine, New Haven, CT, USA
| | - Julia N Eisen
- Department of Internal Medicine, Section of Cardiovascular Medicine, Yale School of Medicine, New Haven, CT, USA
| | - Markus Bögner
- Department of Internal Medicine, Section of Cardiovascular Medicine, Yale School of Medicine, New Haven, CT, USA
| | - Lawrence H Young
- Department of Internal Medicine, Section of Cardiovascular Medicine, Yale School of Medicine, New Haven, CT, USA
| | - Fadi G Akar
- Department of Internal Medicine, Section of Cardiovascular Medicine, Yale School of Medicine, New Haven, CT, USA.
- Department of Biomedical Engineering, Yale University Schools of Engineering and Applied Sciences, New Haven, CT, USA.
- Department of Biomedical Engineering, Electro-biology and Arrhythmia Therapeutics Laboratory, Yale University Schools of Medicine, Engineering and Applied Sciences, 300 George Street, 793 - 748C, New Haven, CT, 06511, USA.
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2
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Sun DK, Zhang N, Liu Y, Qiu JC, Tse G, Li GP, Roever L, Liu T. Dysglycemia and arrhythmias. World J Diabetes 2023; 14:1163-1177. [PMID: 37664481 PMCID: PMC10473954 DOI: 10.4239/wjd.v14.i8.1163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 05/19/2023] [Accepted: 07/05/2023] [Indexed: 08/11/2023] Open
Abstract
Disorders in glucose metabolism can be divided into three separate but interrelated domains, namely hyperglycemia, hypoglycemia, and glycemic variability. Intensive glycemic control in patients with diabetes might increase the risk of hypoglycemic incidents and glucose fluctuations. These three dysglycemic states occur not only amongst patients with diabetes, but are frequently present in other clinical settings, such as during critically ill. A growing body of evidence has focused on the relationships between these dysglycemic domains with cardiac arrhythmias, including supraventricular arrhythmias (primarily atrial fibrillation), ventricular arrhythmias (malignant ventricular arrhythmias and QT interval prolongation), and bradyarrhythmias (bradycardia and heart block). Different mechanisms by which these dysglycemic states might provoke cardiac arr-hythmias have been identified in experimental studies. A customized glycemic control strategy to minimize the risk of hyperglycemia, hypoglycemia and glucose variability is of the utmost importance in order to mitigate the risk of cardiac arrhythmias.
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Affiliation(s)
- Dong-Kun Sun
- Department of Cardiology, Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, China
| | - Nan Zhang
- Department of Cardiology, Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, China
| | - Ying Liu
- Department of Cardiology, Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, China
| | - Jiu-Chun Qiu
- Department of Cardiology, Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, China
| | - Gary Tse
- Department of Cardiology, Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, China
- Kent and Medway Medical School, Kent CT2 7NT, Canterbury, United Kingdom
- School of Nursing and Health Studies, Metropolitan University, Hong Kong 999077, China
| | - Guang-Ping Li
- Department of Cardiology, Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, China
| | - Leonardo Roever
- Department of Clinical Research, Federal University of Uberlândia, Uberlândia, 38400384, MG, Brazil
| | - Tong Liu
- Department of Cardiology, Tianjin Key Laboratory of Ionic-Molecular Function of Cardiovascular Disease, Tianjin Institute of Cardiology, Second Hospital of Tianjin Medical University, Tianjin 300211, China
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3
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Cortassa S, Caceres V, Tocchetti CG, Bernier M, de Cabo R, Paolocci N, Sollott SJ, Aon MA. Metabolic remodelling of glucose, fatty acid and redox pathways in the heart of type 2 diabetic mice. J Physiol 2020; 598:1393-1415. [PMID: 30462352 PMCID: PMC7739175 DOI: 10.1113/jp276824] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 11/15/2018] [Indexed: 12/31/2022] Open
Abstract
KEY POINTS Hearts from type 2 diabetic animals display perturbations in excitation-contraction coupling, impairing myocyte contractility and delaying relaxation, along with altered substrate consumption patterns. Under high glucose and β-adrenergic stimulation conditions, palmitate can, at least in part, offset left ventricle (LV) dysfunction in hearts from diabetic mice, improving contractility and relaxation while restoring coronary perfusion pressure. Fluxome calculations of central catabolism in diabetic hearts show that, in the presence of palmitate, there is a metabolic remodelling involving tricarboxylic acid cycle, polyol and pentose phosphate pathways, leading to improved redox balance in cytoplasmic and mitochondrial compartments. Under high glucose and increased energy demand, the metabolic/fluxomic redirection leading to restored redox balance imparted by palmitate helps explain maintained LV function and may contribute to designing novel therapeutic approaches to prevent cardiac dysfunction in diabetic patients. ABSTRACT Type-2 diabetes (T2DM) leads to reduced myocardial performance, and eventually heart failure. Excessive accumulation of lipids and glucose is central to T2DM cardiomyopathy. Previous data showed that palmitate (Palm) or glutathione preserved heart mitochondrial energy/redox balance under excess glucose, rescuing β-adrenergic-stimulated cardiac excitation-contraction coupling. However, the mechanisms underlying the accompanying improved contractile performance have been largely ignored. Herein we explore in intact heart under substrate excess the metabolic remodelling associated with cardiac function in diabetic db/db mice subjected to stress given by β-adrenergic stimulation with isoproterenol and high glucose compared to their non-diabetic controls (+/+, WT) under euglycaemic conditions. When perfused with Palm, T2DM hearts exhibited improved contractility/relaxation compared to WT, accompanied by extensive metabolic remodelling as demonstrated by metabolomics-fluxomics combined with bioinformatics and computational modelling. The T2DM heart metabolome showed significant differences in the abundance of metabolites in pathways related to glucose, lipids and redox metabolism. Using a validated computational model of heart's central catabolism, comprising glucose and fatty acid (FA) oxidation in cytoplasmic and mitochondrial compartments, we estimated that fluxes through glucose degradation pathways are ∼2-fold lower in heart from T2DM vs. WT under all conditions studied. Palm addition elicits improvement of the redox status via enhanced β-oxidation and decreased glucose uptake, leading to flux-redirection away from redox-consuming pathways (e.g. polyol) while maintaining the flux through redox-generating pathways together with glucose-FA 'shared fuelling' of oxidative phosphorylation. Thus, available FAs such as Palm may help improve function via enhanced redox balance in T2DM hearts during peaks of hyperglycaemia and increased workload.
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Affiliation(s)
- Sonia Cortassa
- Laboratory of Cardiovascular Science, National Institute on Aging/NIH, Baltimore, MD, 21224, USA
| | - Viviane Caceres
- Division of Cardiology, Department of Medicine, The Johns Hopkins University, Baltimore, MD, 21205, USA
- Posgraduate Program in Rehabilitation Sciences, Dept. Health Sciences, Federal University of Santa Catarina, Ararangua, SC, Brazil
| | - Carlo G Tocchetti
- Division of Cardiology, Department of Medicine, The Johns Hopkins University, Baltimore, MD, 21205, USA
- Dipartimento di Scienze Mediche Traslazionali, Universita' degli Studi di Napoli Federico II Via Pansini 5, Edificio 2, 80131, Napoli, Italy
| | - Michel Bernier
- Translational Gerontology Branch, National Institute on Aging/NIH, Baltimore, MD, 21224, USA
| | - Rafael de Cabo
- Translational Gerontology Branch, National Institute on Aging/NIH, Baltimore, MD, 21224, USA
| | - Nazareno Paolocci
- Division of Cardiology, Department of Medicine, The Johns Hopkins University, Baltimore, MD, 21205, USA
- Department of Biomedical Sciences, University of Padova, via Marzolo 3, 35131, Padova, Italy
| | - Steven J Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging/NIH, Baltimore, MD, 21224, USA
| | - Miguel A Aon
- Laboratory of Cardiovascular Science, National Institute on Aging/NIH, Baltimore, MD, 21224, USA
- Translational Gerontology Branch, National Institute on Aging/NIH, Baltimore, MD, 21224, USA
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Vetter L, Cortassa S, O'Rourke B, Armoundas AA, Bedja D, Jende JME, Bendszus M, Paolocci N, Sollot SJ, Aon MA, Kurz FT. Diabetes Increases the Vulnerability of the Cardiac Mitochondrial Network to Criticality. Front Physiol 2020; 11:175. [PMID: 32210835 PMCID: PMC7077512 DOI: 10.3389/fphys.2020.00175] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 02/14/2020] [Indexed: 02/06/2023] Open
Abstract
Mitochondrial criticality describes a state in which the mitochondrial cardiac network under intense oxidative stress becomes very sensitive to small perturbations, leading from local to cell-wide depolarization and synchronized oscillations that may escalate to the myocardial syncytium generating arrhythmias. Herein, we describe the occurrence of mitochondrial criticality in the chronic setting of a metabolic disorder, type 1 diabetes (T1DM), using a streptozotocin (STZ)-treated guinea pig (GP) animal model. Using wavelet analysis of mitochondrial networks from two-photon microscopy imaging of cardiac myocytes loaded with a fluorescent probe of the mitochondrial membrane potential, we show that cardiomyocytes from T1DM GPs are closer to criticality, making them more vulnerable to cell-wide mitochondrial oscillations as can be judged by the latency period to trigger oscillations after a laser flash perturbation, and their propensity to oscillate. Insulin treatment of T1DM GPs rescued cardiac myocytes to sham control levels of susceptibility, a protective condition that could also be attained with interventions leading to improvement of the cellular redox environment such as preincubation of diabetic cardiac myocytes with the lipid palmitate or a cell-permeable form of glutathione, in the presence of glucose.
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Affiliation(s)
- Larissa Vetter
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States.,Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Sonia Cortassa
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Brian O'Rourke
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Antonis A Armoundas
- Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States.,Institute for Medical Engineering and Science, Massachusetts Institute of Technology Cambridge, MA, United States
| | - Djahida Bedja
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD, United States
| | - Johann M E Jende
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Martin Bendszus
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany
| | - Nazareno Paolocci
- Division of Cardiology, Department of Medicine, Johns Hopkins University, Baltimore, MD, United States.,Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Steven J Sollot
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Miguel A Aon
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States
| | - Felix T Kurz
- Department of Neuroradiology, Heidelberg University Hospital, Heidelberg, Germany.,Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, United States
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5
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Song J, Yang R, Yang J, Zhou L. Mitochondrial Dysfunction-Associated Arrhythmogenic Substrates in Diabetes Mellitus. Front Physiol 2018; 9:1670. [PMID: 30574091 PMCID: PMC6291470 DOI: 10.3389/fphys.2018.01670] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 11/07/2018] [Indexed: 12/15/2022] Open
Abstract
There is increasing evidence that diabetic cardiomyopathy increases the risk of cardiac arrhythmia and sudden cardiac death. While the detailed mechanisms remain incompletely understood, the loss of mitochondrial function, which is often observed in the heart of patients with diabetes, has emerged as a key contributor to the arrhythmogenic substrates. In this mini review, the pathophysiology of mitochondrial dysfunction in diabetes mellitus is explored in detail, followed by descriptions of several mechanisms potentially linking mitochondria to arrhythmogenesis in the context of diabetic cardiomyopathy.
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Affiliation(s)
- Jiajia Song
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Ruilin Yang
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States.,Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education, Tianjin University, Tianjin, China
| | - Jing Yang
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
| | - Lufang Zhou
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, United States
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6
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Hamilton S, Terentyev D. Proarrhythmic Remodeling of Calcium Homeostasis in Cardiac Disease; Implications for Diabetes and Obesity. Front Physiol 2018. [PMID: 30425651 DOI: 10.3389/fphys.2018.01517, 10.3389/fpls.2018.01517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
A rapid growth in the incidence of diabetes and obesity has transpired to a major heath issue and economic burden in the postindustrial world, with more than 29 million patients affected in the United States alone. Cardiovascular defects have been established as the leading cause of mortality and morbidity of diabetic patients. Over the last decade, significant progress has been made in delineating mechanisms responsible for the diminished cardiac contractile function and enhanced propensity for malignant cardiac arrhythmias characteristic of diabetic disease. Rhythmic cardiac contractility relies upon the precise interplay between several cellular Ca2+ transport protein complexes including plasmalemmal L-type Ca2+ channels (LTCC), Na+-Ca2+ exchanger (NCX1), Sarco/endoplasmic Reticulum (SR) Ca2+-ATPase (SERCa2a) and ryanodine receptors (RyR2s), the SR Ca2+ release channels. Here we provide an overview of changes in Ca2+ homeostasis in diabetic ventricular myocytes and discuss the therapeutic potential of targeting Ca2+ handling proteins in the prevention of diabetes-associated cardiomyopathy and arrhythmogenesis.
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Affiliation(s)
- Shanna Hamilton
- Department of Medicine, The Warren Alpert Medical School of Brown University, Providence, RI, United States.,Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, United States
| | - Dmitry Terentyev
- Department of Medicine, The Warren Alpert Medical School of Brown University, Providence, RI, United States.,Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, United States
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7
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Hamilton S, Terentyev D. Proarrhythmic Remodeling of Calcium Homeostasis in Cardiac Disease; Implications for Diabetes and Obesity. Front Physiol 2018; 9:1517. [PMID: 30425651 PMCID: PMC6218530 DOI: 10.3389/fphys.2018.01517] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/09/2018] [Indexed: 12/28/2022] Open
Abstract
A rapid growth in the incidence of diabetes and obesity has transpired to a major heath issue and economic burden in the postindustrial world, with more than 29 million patients affected in the United States alone. Cardiovascular defects have been established as the leading cause of mortality and morbidity of diabetic patients. Over the last decade, significant progress has been made in delineating mechanisms responsible for the diminished cardiac contractile function and enhanced propensity for malignant cardiac arrhythmias characteristic of diabetic disease. Rhythmic cardiac contractility relies upon the precise interplay between several cellular Ca2+ transport protein complexes including plasmalemmal L-type Ca2+ channels (LTCC), Na+-Ca2+ exchanger (NCX1), Sarco/endoplasmic Reticulum (SR) Ca2+-ATPase (SERCa2a) and ryanodine receptors (RyR2s), the SR Ca2+ release channels. Here we provide an overview of changes in Ca2+ homeostasis in diabetic ventricular myocytes and discuss the therapeutic potential of targeting Ca2+ handling proteins in the prevention of diabetes-associated cardiomyopathy and arrhythmogenesis.
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Affiliation(s)
- Shanna Hamilton
- Department of Medicine, The Warren Alpert Medical School of Brown University, Providence, RI, United States.,Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, United States
| | - Dmitry Terentyev
- Department of Medicine, The Warren Alpert Medical School of Brown University, Providence, RI, United States.,Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, United States
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8
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Hamilton S, Terentyev D. Proarrhythmic Remodeling of Calcium Homeostasis in Cardiac Disease; Implications for Diabetes and Obesity. Front Physiol 2018; 9:1517. [PMID: 30425651 PMCID: PMC6218530 DOI: 10.3389/fphys.2018.01517,+10.3389/fpls.2018.01517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/06/2022] Open
Abstract
A rapid growth in the incidence of diabetes and obesity has transpired to a major heath issue and economic burden in the postindustrial world, with more than 29 million patients affected in the United States alone. Cardiovascular defects have been established as the leading cause of mortality and morbidity of diabetic patients. Over the last decade, significant progress has been made in delineating mechanisms responsible for the diminished cardiac contractile function and enhanced propensity for malignant cardiac arrhythmias characteristic of diabetic disease. Rhythmic cardiac contractility relies upon the precise interplay between several cellular Ca2+ transport protein complexes including plasmalemmal L-type Ca2+ channels (LTCC), Na+-Ca2+ exchanger (NCX1), Sarco/endoplasmic Reticulum (SR) Ca2+-ATPase (SERCa2a) and ryanodine receptors (RyR2s), the SR Ca2+ release channels. Here we provide an overview of changes in Ca2+ homeostasis in diabetic ventricular myocytes and discuss the therapeutic potential of targeting Ca2+ handling proteins in the prevention of diabetes-associated cardiomyopathy and arrhythmogenesis.
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Affiliation(s)
- Shanna Hamilton
- Department of Medicine, The Warren Alpert Medical School of Brown University, Providence, RI, United States,Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, United States
| | - Dmitry Terentyev
- Department of Medicine, The Warren Alpert Medical School of Brown University, Providence, RI, United States,Cardiovascular Research Center, Rhode Island Hospital, Providence, RI, United States,*Correspondence: Dmitry Terentyev,
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9
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Cortassa S, Sollott SJ, Aon MA. Mitochondrial respiration and ROS emission during β-oxidation in the heart: An experimental-computational study. PLoS Comput Biol 2017; 13:e1005588. [PMID: 28598967 PMCID: PMC5482492 DOI: 10.1371/journal.pcbi.1005588] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 06/23/2017] [Accepted: 05/23/2017] [Indexed: 12/11/2022] Open
Abstract
Lipids are main fuels for cellular energy and mitochondria their major oxidation site. Yet unknown is to what extent the fuel role of lipids is influenced by their uncoupling effects, and how this affects mitochondrial energetics, redox balance and the emission of reactive oxygen species (ROS). Employing a combined experimental-computational approach, we comparatively analyze β-oxidation of palmitoyl CoA (PCoA) in isolated heart mitochondria from Sham and streptozotocin (STZ)-induced type 1 diabetic (T1DM) guinea pigs (GPs). Parallel high throughput measurements of the rates of oxygen consumption (VO2) and hydrogen peroxide (H2O2) emission as a function of PCoA concentration, in the presence of L-carnitine and malate, were performed. We found that PCoA concentration < 200 nmol/mg mito protein resulted in low H2O2 emission flux, increasing thereafter in Sham and T1DM GPs under both states 4 and 3 respiration with diabetic mitochondria releasing higher amounts of ROS. Respiratory uncoupling and ROS excess occurred at PCoA > 600 nmol/mg mito prot, in both control and diabetic animals. Also, for the first time, we show that an integrated two compartment mitochondrial model of β-oxidation of long-chain fatty acids and main energy-redox processes is able to simulate the relationship between VO2 and H2O2 emission as a function of lipid concentration. Model and experimental results indicate that PCoA oxidation and its concentration-dependent uncoupling effect, together with a partial lipid-dependent decrease in the rate of superoxide generation, modulate H2O2 emission as a function of VO2. Results indicate that keeping low levels of intracellular lipid is crucial for mitochondria and cells to maintain ROS within physiological levels compatible with signaling and reliable energy supply.
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Affiliation(s)
- Sonia Cortassa
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States of America
| | - Steven J. Sollott
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States of America
| | - Miguel A. Aon
- Laboratory of Cardiovascular Science, National Institute on Aging, National Institutes of Health, Baltimore, MD, United States of America
- * E-mail:
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10
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Podell BK, Ackart DF, Richardson MA, DiLisio JE, Pulford B, Basaraba RJ. A model of type 2 diabetes in the guinea pig using sequential diet-induced glucose intolerance and streptozotocin treatment. Dis Model Mech 2017; 10:151-162. [PMID: 28093504 PMCID: PMC5312002 DOI: 10.1242/dmm.025593] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 12/07/2016] [Indexed: 01/04/2023] Open
Abstract
Type 2 diabetes is a leading cause of morbidity and mortality among noncommunicable diseases, and additional animal models that more closely replicate the pathogenesis of human type 2 diabetes are needed. The goal of this study was to develop a model of type 2 diabetes in guinea pigs, in which diet-induced glucose intolerance precedes β-cell cytotoxicity, two processes that are crucial to the development of human type 2 diabetes. Guinea pigs developed impaired glucose tolerance after 8 weeks of feeding on a high-fat, high-carbohydrate diet, as determined by oral glucose challenge. Diet-induced glucose intolerance was accompanied by β-cell hyperplasia, compensatory hyperinsulinemia, and dyslipidemia with hepatocellular steatosis. Streptozotocin (STZ) treatment alone was ineffective at inducing diabetic hyperglycemia in guinea pigs, which failed to develop sustained glucose intolerance or fasting hyperglycemia and returned to euglycemia within 21 days after treatment. However, when high-fat, high-carbohydrate diet-fed guinea pigs were treated with STZ, glucose intolerance and fasting hyperglycemia persisted beyond 21 days post-STZ treatment. Guinea pigs with diet-induced glucose intolerance subsequently treated with STZ demonstrated an insulin-secretory capacity consistent with insulin-independent diabetes. This insulin-independent state was confirmed by response to oral antihyperglycemic drugs, metformin and glipizide, which resolved glucose intolerance and extended survival compared with guinea pigs with uncontrolled diabetes. In this study, we have developed a model of sequential glucose intolerance and β-cell loss, through high-fat, high-carbohydrate diet and extensive optimization of STZ treatment in the guinea pig, which closely resembles human type 2 diabetes. This model will prove useful in the study of insulin-independent diabetes pathogenesis with or without comorbidities, where the guinea pig serves as a relevant model species.
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Affiliation(s)
- Brendan K Podell
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - David F Ackart
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Michael A Richardson
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - James E DiLisio
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Bruce Pulford
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Randall J Basaraba
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
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11
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Xie C, Hu J, Motloch LJ, Karam BS, Akar FG. The Classically Cardioprotective Agent Diazoxide Elicits Arrhythmias in Type 2 Diabetes Mellitus. J Am Coll Cardiol 2015; 66:1144-1156. [PMID: 26337994 DOI: 10.1016/j.jacc.2015.06.1329] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 06/06/2015] [Accepted: 06/23/2015] [Indexed: 01/19/2023]
Abstract
BACKGROUND Type 2 diabetes mellitus (T2DM) is associated with an enhanced propensity for ventricular tachyarrhythmias (VTs) under conditions of metabolic demand. Activation of mitochondrial adenosine triphosphate-sensitive potassium (KATP) channels by low-dose diazoxide (DZX) improves hypoglycemia-related complications, metabolic function, and triglyceride and free fatty acid levels and reverses weight gain in T2DM. OBJECTIVES In this study, we hypothesized that DZX prevents ischemia-mediated arrhythmias in T2DM via its putative cardioprotective and antidiabetic property. METHODS Zucker obese diabetic fatty (ZO) rats (n = 43) with T2DM were studied. Controls consisted of Zucker lean (ZL; n = 13) and normal Sprague-Dawley (SprD; n = 30) rats. High-resolution optical action potential mapping was performed before and during challenge with no-flow ischemia for 12 min. RESULTS Electrophysiological properties were relatively stable in T2DM hearts at baseline. In contrast, ischemia uncovered major differences between groups, because action potential duration (APD) in T2DM failed to undergo progressive adaptation to ischemic challenge. DZX promoted the incidence of arrhythmias, because all DZX-treated T2DM hearts exhibited ischemia-induced VTs that persisted on reperfusion. In contrast, untreated T2DM and controls did not exhibit VT during ischemia. Unlike DZX, pinacidil promoted ischemia-mediated arrhythmias in both control and T2DM hearts. Rapid and spatially heterogeneous shortening of APD preceded the onset of arrhythmias in T2DM. DZX-mediated proarrhythmia in T2DM was not related to changes in the messenger ribonucleic acid expression of Kir6.1, Kir6.2, SUR1A, SUR1B, SUR2A, SUR2B, or ROMK (renal outer medullary potassium channel). CONCLUSIONS Ischemia uncovers a paradoxical resistance of T2DM hearts to APD adaptation. DZX reverses this property, resulting in rapid and heterogeneous APD shortening. This promotes reentrant VT during ischemia. DZX should be avoided in diabetic patients at risk of ischemic events.
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Affiliation(s)
- Chaoqin Xie
- Cardiac Bioelectricity Research Laboratory, Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Jun Hu
- Cardiac Bioelectricity Research Laboratory, Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Lukas J Motloch
- Cardiac Bioelectricity Research Laboratory, Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Basil S Karam
- Cardiac Bioelectricity Research Laboratory, Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Fadi G Akar
- Cardiac Bioelectricity Research Laboratory, Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, New York, New York
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12
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Radenković M, Stojanović M, Prostran M. Experimental diabetes induced by alloxan and streptozotocin: The current state of the art. J Pharmacol Toxicol Methods 2015; 78:13-31. [PMID: 26596652 DOI: 10.1016/j.vascn.2015.11.004] [Citation(s) in RCA: 143] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Revised: 11/14/2015] [Accepted: 11/15/2015] [Indexed: 12/13/2022]
Abstract
Diabetes mellitus is a chronic metabolic disorder with a high prevalence worldwide. Animal models of diabetes represent an important tool in diabetes investigation that helps us to avoid unnecessary and ethically challenging studies in human subjects, as well as to obtain a comprehensive scientific viewpoint of this disease. Although there are several methods through which diabetes can be induced, chemical methods of alloxan- and streptozotocin-induced diabetes represent the most important and highly preferable experimental models for this pathological condition. Therefore, the aim of this article was to review the current knowledge related to quoted models of diabetes, including to this point available information about mechanism of action, particular time- and dose-dependent protocols, frequent problems, as well as major limitations linked to laboratory application of alloxan and sterptozotocin in inducing diabetes. Given that diabetes is known to be closely associated with serious health consequences it is of fundamental importance that current animal models for induction of diabetes should be continuously upgraded in order to improve overall prevention, diagnosis and treatment of this pathological condition.
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Affiliation(s)
- Miroslav Radenković
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, PO Box 38, 11129 Belgrade, Serbia.
| | - Marko Stojanović
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, PO Box 38, 11129 Belgrade, Serbia.
| | - Milica Prostran
- Department of Pharmacology, Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Belgrade, PO Box 38, 11129 Belgrade, Serbia.
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13
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Impaired mitochondrial energy supply coupled to increased H2O2 emission under energy/redox stress leads to myocardial dysfunction during Type I diabetes. Clin Sci (Lond) 2015; 129:561-74. [PMID: 26186741 DOI: 10.1042/cs20150204] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 05/29/2015] [Indexed: 12/23/2022]
Abstract
In Type I diabetic (T1DM) patients, both peaks of hyperglycaemia and increased sympathetic tone probably contribute to impair systolic and diastolic function. However, how these stressors eventually alter cardiac function during T1DM is not fully understood. In the present study, we hypothesized that impaired mitochondrial energy supply and excess reactive oxygen species (ROS) emission is centrally involved in T1DM cardiac dysfunction due to metabolic/redox stress and aimed to determine the mitochondrial sites implicated in these alterations. To this end, we used isolated myocytes and mitochondria from Sham and streptozotocin (STZ)-induced T1DM guinea pigs (GPs), untreated or treated with insulin. Relative to controls, T1DM myocytes exhibited higher oxidative stress when challenged with high glucose (HG) combined with β-adrenergic stimulation [via isoprenaline (isoproterenol) (ISO)], leading to contraction/relaxation deficits. T1DM mitochondria had decreased respiration with complex II and IV substrates and markedly lower ADP phosphorylation rates and higher H2O2 emission when challenged with oxidants to mimic the more oxidized redox milieu present in HG + ISO-treated cardiomyocytes. Since in T1DM hearts insulin-sensitivity is preserved and a glucose-to-fatty acid (FA) shift occurs, we next tested whether insulin therapy or acute palmitate (Palm) infusion prevents HG + ISO-induced cardiac dysfunction. We found that insulin rescued proper cardiac redox balance, but not mitochondrial respiration or contractile performance. Conversely, Palm restored redox balance and preserved myocyte function. Thus, stressors such as peaks of HG and adrenergic hyperactivity impair mitochondrial respiration, hampering energy supply while exacerbating ROS emission. Our study suggests that an ideal therapeutic measure to treat metabolically/redox-challenged T1DM hearts should concomitantly correct energetic and redox abnormalities to fully maintain cardiac function.
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14
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The mitochondrial translocator protein and arrhythmogenesis in ischemic heart disease. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2015:234104. [PMID: 25918579 PMCID: PMC4397036 DOI: 10.1155/2015/234104] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 03/18/2015] [Indexed: 12/19/2022]
Abstract
Mitochondrial dysfunction is a hallmark of multiple cardiovascular disorders, including ischemic heart disease. Although mitochondria are well recognized for their role in energy production and cell death, mechanisms by which they control excitation-contraction coupling, excitability, and arrhythmias are less clear. The translocator protein (TSPO) is an outer mitochondrial membrane protein that is expressed in multiple organ systems. The abundant expression of TSPO in macrophages has been leveraged to image the immune response of the heart to inflammatory processes. More recently, the recognition of TSPO as a regulator of energy-dissipating mitochondrial pathways has extended its utility from a diagnostic marker of inflammation to a therapeutic target influencing diverse pathophysiological processes. Here, we provide an overview of the emerging role of TSPO in ischemic heart disease. We highlight the importance of TSPO in the regenerative process of reactive oxygen species (ROS) induced ROS release through its effects on the inner membrane anion channel (IMAC) and the permeability transition pore (PTP). We discuss evidence implicating TSPO in arrhythmogenesis in the settings of acute ischemia-reperfusion injury and myocardial infarction.
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15
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Ovechkin AO, Vaykshnorayte MA, Sedova K, Shumikhin KV, Arteyeva NV, Azarov JE. Functional role of myocardial electrical remodeling in diabetic rabbits. Can J Physiol Pharmacol 2014; 93:245-52. [PMID: 25666101 DOI: 10.1139/cjpp-2014-0293] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The objective of the study was to investigate the role of electrical remodeling of the ventricular myocardium in hemodynamic impairment and the development of arrhythmogenic substrate. Experiments were conducted with 11 healthy and 12 diabetic (alloxan model, 4 weeks) rabbits. Left ventricular pressure was monitored and unipolar electrograms were recorded from 64 epicardial leads. Aortic banding was used to provoke arrhythmia. The diabetic rabbits had prolonged QTc, with activation-recovery intervals (surrogates for repolarization durations) being relatively short on the left ventricular base and long on the anterior apical portions of both ventricles (P < 0.05). In the diabetic rabbits, a negative correlation (-0.726 to -0.817) was observed between dP/dt(max), dP/dt(min), and repolarization dispersions. Under conditions of systolic overload (5 min), tachyarrhythmias were equally rare and the QTc and activation-recovery intervals were shortened in both groups (P < 0.05), whereas QRS was prolonged in the diabetic rabbits only. The repolarization shortening was more pronounced on the apex, which led to the development of apicobasal and interventricular end of repolarization gradients in the healthy animals, and to the flattening of the repolarization profile in the diabetic group. Thus, the diabetes-related pattern of ventricular repolarization was associated with inotropic and lusitropic impairment of the cardiac pump function.
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Affiliation(s)
- Alexey O Ovechkin
- Laboratory of Cardiac Physiology, Institute of Physiology, Komi Science Center, Ural Branch, Russian Academy of Sciences, 50 Pervomayskaya Street, 167982 Syktyvkar, Russia., First Department of Internal Diseases of Komi Branch of Kirov State Medical Academy, 11 Babushkin Street, Syktyvkar 167000, Russia., Department of Physiology, Medical Institute of Syktyvkar State University, 11 Babushkin Street, Syktyvkar 167000, Russia
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Xie C, Kauffman J, Akar FG. Functional crosstalk between the mitochondrial PTP and KATP channels determine arrhythmic vulnerability to oxidative stress. Front Physiol 2014; 5:264. [PMID: 25076913 PMCID: PMC4099963 DOI: 10.3389/fphys.2014.00264] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 06/24/2014] [Indexed: 01/18/2023] Open
Abstract
Background: Mitochondrial permeability transition pore (mPTP) opening is a terminal event leading to mitochondrial dysfunction and cell death under conditions of oxidative stress (OS). However, mPTP blockade with cyclosporine A (CsA) has shown variable efficacy in limiting post-ischemic dysfunction and arrhythmias. We hypothesized that strong feedback between energy dissipating (mPTP) and cardioprotective (mKATP) channels determine vulnerability to OS. Methods and Results: Guinea pig hearts (N = 61) were challenged with H2O2 (200 μM) to elicit mitochondrial membrane potential (ΔΨm) depolarization. High-resolution optical mapping was used to measure ΔΨm or action potentials (AP) across the intact heart. Hearts were treated with CsA (0.1 μM) under conditions that altered the activity of mKATP channels either directly or indirectly via its regulation by protein kinase C. mPTP blockade with CsA markedly blunted (P < 0.01) OS-induced ΔΨm depolarization and delayed loss of LV pressure (LVP), but did not affect arrhythmia propensity. Surprisingly, prevention of mKATP activation with the chemical phosphatase BDM reversed the protective effect of CsA, paradoxically exacerbating OS-induced ΔΨm depolarization and accelerating arrhythmia onset in CsA treated compared to untreated hearts (P < 0.05). To elucidate the putative molecular mechanisms, mPTP inhibition by CsA was tested during conditions of selective PKC inhibition or direct mKATP channel activation or blockade. Similar to BDM, the specific PKC inhibitor, CHE (10 μM) did not alter OS-induced ΔΨm depolarization directly. However, it completely abrogated CsA-mediated protection against OS. Direct pharmacological blockade of mKATP, a mitochondrial target of PKC signaling, equally abolished the protective effect of CsA on ΔΨm depolarization, whereas channel activation with 30 μM Diazoxide protected against ΔΨm depolarization (P < 0.0001). Conditions that prevented mKATP activation either directly or indirectly via PKC inhibition led to accelerated ΔΨm depolarization and early onset of VF in response to OS. Investigation of the electrophysiological substrate revealed accelerated APD shortening in response to OS in arrhythmia-prone hearts. Conclusions: Cardioprotection by CsA requires mKATP channel activation through a PKC-dependent pathway. Increasing mKATP activity during CsA administration is required for limiting OS-induced electrical dysfunction.
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Affiliation(s)
- Chaoqin Xie
- Department of Medicine, Cardiovascular Institute, Mount Sinai School of Medicine New York, NY, USA
| | - Justin Kauffman
- Department of Medicine, Cardiovascular Institute, Mount Sinai School of Medicine New York, NY, USA
| | - Fadi G Akar
- Department of Medicine, Cardiovascular Institute, Mount Sinai School of Medicine New York, NY, USA
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Stables CL, Musa H, Mitra A, Bhushal S, Deo M, Guerrero-Serna G, Mironov S, Zarzoso M, Vikstrom KL, Cawthorn W, Pandit SV. Reduced Na⁺ current density underlies impaired propagation in the diabetic rabbit ventricle. J Mol Cell Cardiol 2014; 69:24-31. [PMID: 24412579 DOI: 10.1016/j.yjmcc.2013.12.031] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Revised: 12/23/2013] [Accepted: 12/31/2013] [Indexed: 12/12/2022]
Abstract
Diabetes is associated with an increased risk of sudden cardiac death, but the underlying mechanisms remain unclear. Our goal was to investigate changes occurring in the action potential duration (APD) and conduction velocity (CV) in the diabetic rabbit ventricle, and delineate the principal ionic determinants. A rabbit model of alloxan-induced diabetes was utilized. Optical imaging was used to record electrical activity in isolated Langendorff-perfused hearts in normo-, hypo- and hyper-kalemia ([K(+)]o=4, 2, 12 mM respectively). Patch clamp experiments were conducted to record Na(+) current (I(Na)) in isolated ventricular myocytes. The mRNA/protein expression levels for Nav1.5 (the α-subunit of I(Na)) and connexin-43 (Cx43), as well as fibrosis levels were examined. Computer simulations were performed to interpret experimental data. We found that the APD was not different, but the CV was significantly reduced in diabetic hearts in normo-, hypo-, and, hyper-kalemic conditions (13%, 17% and 33% reduction in diabetic vs. control, respectively). The cell capacitance (Cm) was increased (by ~14%), and the density of INa was reduced by ~32% in diabetic compared to control hearts, but the other biophysical properties of I(Na) were unaltered. The mRNA/protein expression levels for Cx43 were unaltered. For Nav1.5, the mRNA expression was not changed, and though the protein level tended to be less in diabetic hearts, this reduction was not statistically significant. Staining showed no difference in fibrosis levels between the control and diabetic ventricles. Computer simulations showed that the reduced magnitude of I(Na) was a key determinant of impaired propagation in the diabetic ventricle, which may have important implications for arrhythmogenesis.
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Affiliation(s)
- Catherine L Stables
- Center for Arrhythmia Research, Department of Internal Medicine-Cardiology, University of Michigan, Ann Arbor, MI, USA
| | - Hassan Musa
- Center for Arrhythmia Research, Department of Internal Medicine-Cardiology, University of Michigan, Ann Arbor, MI, USA
| | - Aditi Mitra
- Center for Arrhythmia Research, Department of Internal Medicine-Cardiology, University of Michigan, Ann Arbor, MI, USA
| | - Sandesh Bhushal
- Department of Engineering, Norfolk State University, Norfolk, VA, USA
| | - Makarand Deo
- Department of Engineering, Norfolk State University, Norfolk, VA, USA
| | - Guadalupe Guerrero-Serna
- Center for Arrhythmia Research, Department of Internal Medicine-Cardiology, University of Michigan, Ann Arbor, MI, USA
| | - Sergey Mironov
- Center for Arrhythmia Research, Department of Internal Medicine-Cardiology, University of Michigan, Ann Arbor, MI, USA
| | - Manuel Zarzoso
- Center for Arrhythmia Research, Department of Internal Medicine-Cardiology, University of Michigan, Ann Arbor, MI, USA
| | - Karen L Vikstrom
- Center for Arrhythmia Research, Department of Internal Medicine-Cardiology, University of Michigan, Ann Arbor, MI, USA
| | - William Cawthorn
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Sandeep V Pandit
- Center for Arrhythmia Research, Department of Internal Medicine-Cardiology, University of Michigan, Ann Arbor, MI, USA.
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