1
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Yan M, Lin K, Huang D, Li J, Qu X, Chen K. Semaglutide attenuates pathological electrophysiological remodeling in diabetic cardiomyopathy via restoring Cx43 expression. Endocrine 2024; 84:969-979. [PMID: 38647981 DOI: 10.1007/s12020-024-03823-2] [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: 01/24/2024] [Accepted: 04/04/2024] [Indexed: 04/25/2024]
Abstract
BACKGROUND Semaglutide is a relatively new anti-hyperglycemic agent that was shown to carry cardioprotective potentials. However, the exact effects of semaglutide on diabetic cardiomyopathy (DCM) and their underlining mechanism remain unclear. This study aimed to evaluate the effects of semaglutide on myocardium injury and cardiac function in DCM mice and its potential mechanisms, with emphasis on its effects on Cx43 and electrophysiological remodeling. METHODS C57BL/6 mice were randomly divided into four groups: control group, semaglutide group, diabetes group, and diabetes + semaglutide treatment group. Type 1 diabetes were induced by intraperitoneal injection of streptozotocin. Mice in the semaglutide intervention group were injected subcutaneously with semaglutide (0.15 mg/kg) every week for 8 weeks. The blood glucose, cardiac function, oxidative stress markers, apoptosis, expression of Sirt1, AMPK, Cx43, and electrocardiogram of mice in each group were evaluated. RESULTS Treatment with semaglutide alleviated glucose metabolism disorders and improved cardiac dysfunction in diabetic mice. In addition, semaglutide ameliorated the increase in oxidative stress and apoptosis in diabetic heart. Sirt1/AMPK pathway was activated after semaglutide treatment. Furthermore, diabetic mice showed reduced expression of Cx43 in the myocardium, accompanied by changes in electrocardiogram, including significantly prolonged RR, QRS, QT and QTc interval. Semaglutide treatment restored Cx43 expression and reversed the above-mentioned ECG abnormalities. CONCLUSIONS Our research results showed that semaglutide protected against oxidative stress and apoptosis in diabetic heart, thereby improving cardiac function and electrophysiological remodelling in DCM mice, which may attribute to activation of Sirt1/AMPK pathway and restore of Cx43 expression.
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Affiliation(s)
- Meiling Yan
- Department of Cardiology, Huadong Hospital Affiliated to Fudan University, Shanghai, 200040, China
| | - Kaibin Lin
- Department of Cardiology, Shanghai Institute of Cardiovascular Diseases, Zhongshan Hospital, Fudan University, Shanghai, 200032, China
| | - Dong Huang
- Department of Cardiology, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
| | - Jingbo Li
- Department of Cardiology, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China
| | - Xinkai Qu
- Department of Cardiology, Huadong Hospital Affiliated to Fudan University, Shanghai, 200040, China.
| | - Kankai Chen
- Department of Cardiology, Shanghai Sixth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, 200233, China.
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Zheng M, Erhardt S, Cao Y, Wang J. Emerging Signaling Regulation of Sinoatrial Node Dysfunction. Curr Cardiol Rep 2023; 25:621-630. [PMID: 37227579 DOI: 10.1007/s11886-023-01885-8] [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] [Accepted: 04/14/2023] [Indexed: 05/26/2023]
Abstract
PURPOSE OF REVIEW The sinoatrial node (SAN), the natural pacemaker of the heart, is responsible for generating electrical impulses and initiating each heartbeat. Sinoatrial node dysfunction (SND) causes various arrhythmias such as sinus arrest, SAN block, and tachycardia/bradycardia syndrome. Unraveling the underlying mechanisms of SND is of paramount importance in the pursuit of developing effective therapeutic strategies for patients with SND. This review provides a concise summary of the most recent progress in the signaling regulation of SND. RECENT FINDINGS Recent studies indicate that SND can be caused by abnormal intercellular and intracellular signaling, various forms of heart failure (HF), and diabetes. These discoveries provide novel insights into the underlying mechanisms SND, advancing our understanding of its pathogenesis. SND can cause severe cardiac arrhythmias associated with syncope and an increased risk of sudden death. In addition to ion channels, the SAN is susceptible to the influence of various signalings including Hippo, AMP-activated protein kinase (AMPK), mechanical force, and natriuretic peptide receptors. New cellular and molecular mechanisms related to SND are also deciphered in systemic diseases such as HF and diabetes. Progress in these studies contributes to the development of potential therapeutics for SND.
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Affiliation(s)
- Mingjie Zheng
- Department of Pediatrics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Shannon Erhardt
- Department of Pediatrics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, The University of Texas, Houston, TX, 77030, USA
| | - Yuhan Cao
- Department of Pediatrics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - Jun Wang
- Department of Pediatrics, McGovern Medical School, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA.
- MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, The University of Texas, Houston, TX, 77030, USA.
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3
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Sultan A, Adeghate E, Emerald BS, Qureshi MA, Minhas ST, Howarth FC. Effects of Obesity and Diabesity on Ventricular Muscle Structure and Function in the Zucker Rat. Life (Basel) 2022; 12:1221. [PMID: 36013400 PMCID: PMC9410105 DOI: 10.3390/life12081221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 08/03/2022] [Accepted: 08/04/2022] [Indexed: 06/15/2023] Open
Abstract
(1) Background: Cardiovascular complications are a leading cause of morbidity and mortality in diabetic patients. The effects of obesity and diabesity on the function and structure of ventricular myocytes in the Zucker fatty (ZF) rat and the Zucker diabetic fatty (ZDF) rat compared to Zucker lean (ZL) control rats have been investigated. (2) Methods: Shortening and intracellular Ca2+ were simultaneously measured with cell imaging and fluorescence photometry, respectively. Ventricular muscle protein expression and structure were investigated with Western blot and electron microscopy, respectively. (3) Results: The amplitude of shortening was increased in ZF compared to ZL but not compared to ZDF myocytes. Resting Ca2+ was increased in ZDF compared to ZL myocytes. Time to half decay of the Ca2+ transient was prolonged in ZDF compared to ZL and was reduced in ZF compared to ZL myocytes. Changes in expression of proteins associated with cardiac muscle contraction are presented. Structurally, there were reductions in sarcomere length in ZDF and ZF compared to ZL and reductions in mitochondria count in ZF compared to ZDF and ZL myocytes. (4) Conclusions: Alterations in ventricular muscle proteins and structure may partly underlie the defects observed in Ca2+ signaling in ZDF and ZF compared to ZL rat hearts.
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Affiliation(s)
- Ahmed Sultan
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain P.O. Box 17666, United Arab Emirates
| | - Ernest Adeghate
- Department of Anatomy, College of Medicine & Health Sciences, UAE University, Al Ain P.O. Box 17666, United Arab Emirates
| | - Bright Starling Emerald
- Department of Anatomy, College of Medicine & Health Sciences, UAE University, Al Ain P.O. Box 17666, United Arab Emirates
| | - Muhammad A. Qureshi
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain P.O. Box 17666, United Arab Emirates
| | - Saeed Tariq Minhas
- Department of Anatomy, College of Medicine & Health Sciences, UAE University, Al Ain P.O. Box 17666, United Arab Emirates
| | - Frank Christopher Howarth
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain P.O. Box 17666, United Arab Emirates
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4
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Ca 2+ mishandling and mitochondrial dysfunction: a converging road to prediabetic and diabetic cardiomyopathy. Pflugers Arch 2022; 474:33-61. [PMID: 34978597 PMCID: PMC8721633 DOI: 10.1007/s00424-021-02650-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 11/17/2021] [Accepted: 12/03/2021] [Indexed: 12/16/2022]
Abstract
Diabetic cardiomyopathy is defined as the myocardial dysfunction that suffers patients with diabetes mellitus (DM) in the absence of hypertension and structural heart diseases such as valvular or coronary artery dysfunctions. Since the impact of DM on cardiac function is rather silent and slow, early stages of diabetic cardiomyopathy, known as prediabetes, are poorly recognized, and, on many occasions, cardiac illness is diagnosed only after a severe degree of dysfunction was reached. Therefore, exploration and recognition of the initial pathophysiological mechanisms that lead to cardiac dysfunction in diabetic cardiomyopathy are of vital importance for an on-time diagnosis and treatment of the malady. Among the complex and intricate mechanisms involved in diabetic cardiomyopathy, Ca2+ mishandling and mitochondrial dysfunction have been described as pivotal early processes. In the present review, we will focus on these two processes and the molecular pathway that relates these two alterations to the earlier stages and the development of diabetic cardiomyopathy.
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5
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Al Kury LT, Chacar S, Alefishat E, Khraibi AA, Nader M. Structural and Electrical Remodeling of the Sinoatrial Node in Diabetes: New Dimensions and Perspectives. Front Endocrinol (Lausanne) 2022; 13:946313. [PMID: 35872997 PMCID: PMC9302195 DOI: 10.3389/fendo.2022.946313] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/14/2022] [Indexed: 11/14/2022] Open
Abstract
The sinoatrial node (SAN) is composed of highly specialized cells that mandate the spontaneous beating of the heart through self-generation of an action potential (AP). Despite this automaticity, the SAN is under the modulation of the autonomic nervous system (ANS). In diabetes mellitus (DM), heart rate variability (HRV) manifests as a hallmark of diabetic cardiomyopathy. This is paralleled by an impaired regulation of the ANS, and by a pathological remodeling of the pacemaker structure and function. The direct effect of diabetes on the molecular signatures underscoring this pathology remains ill-defined. The recent focus on the electrical currents of the SAN in diabetes revealed a repressed firing rate of the AP and an elongation of its tracing, along with conduction abnormalities and contractile failure. These changes are blamed on the decreased expression of ion transporters and cell-cell communication ports at the SAN (i.e., HCN4, calcium and potassium channels, connexins 40, 45, and 46) which further promotes arrhythmias. Molecular analysis crystallized the RGS4 (regulator of potassium currents), mitochondrial thioredoxin-2 (reactive oxygen species; ROS scavenger), and the calcium-dependent calmodulin kinase II (CaMKII) as metabolic culprits of relaying the pathological remodeling of the SAN cells (SANCs) structure and function. A special attention is given to the oxidation of CaMKII and the generation of ROS that induce cell damage and apoptosis of diabetic SANCs. Consequently, the diabetic SAN contains a reduced number of cells with significant infiltration of fibrotic tissues that further delay the conduction of the AP between the SANCs. Failure of a genuine generation of AP and conduction of their derivative waves to the neighboring atrial myocardium may also occur as a result of the anti-diabetic regiment (both acute and/or chronic treatments). All together, these changes pose a challenge in the field of cardiology and call for further investigations to understand the etiology of the structural/functional remodeling of the SANCs in diabetes. Such an understanding may lead to more adequate therapies that can optimize glycemic control and improve health-related outcomes in patients with diabetes.
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Affiliation(s)
- Lina T. Al Kury
- Department of Health Sciences, College of Natural and Health Sciences, Zayed University, Abu Dhabi, United Arab Emirates
- *Correspondence: Lina T. Al Kury, ; Moni Nader,
| | - Stephanie Chacar
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
| | - Eman Alefishat
- Department of Pharmacology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Department of Biopharmaceutics and Clinical Pharmacy, School of Pharmacy, The University of Jordan, Amman, Jordan
- Center for Biotechnology, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
| | - Ali A. Khraibi
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Center for Biotechnology, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
| | - Moni Nader
- Department of Physiology and Immunology, College of Medicine and Health Sciences, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- Center for Biotechnology, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
- *Correspondence: Lina T. Al Kury, ; Moni Nader,
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Gallego M, Zayas-Arrabal J, Alquiza A, Apellaniz B, Casis O. Electrical Features of the Diabetic Myocardium. Arrhythmic and Cardiovascular Safety Considerations in Diabetes. Front Pharmacol 2021; 12:687256. [PMID: 34305599 PMCID: PMC8295895 DOI: 10.3389/fphar.2021.687256] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 06/15/2021] [Indexed: 12/20/2022] Open
Abstract
Diabetes is a chronic metabolic disease characterized by hyperglycemia in the absence of treatment. Among the diabetes-associated complications, cardiovascular disease is the major cause of mortality and morbidity in diabetic patients. Diabetes causes a complex myocardial dysfunction, referred as diabetic cardiomyopathy, which even in the absence of other cardiac risk factors results in abnormal diastolic and systolic function. Besides mechanical abnormalities, altered electrical function is another major feature of the diabetic myocardium. Both type 1 and type 2 diabetic patients often show cardiac electrical remodeling, mainly a prolonged ventricular repolarization visible in the electrocardiogram as a lengthening of the QT interval duration. The underlying mechanisms at the cellular level involve alterations on the expression and activity of several cardiac ion channels and their associated regulatory proteins. Consequent changes in sodium, calcium and potassium currents collectively lead to a delay in repolarization that can increase the risk of developing life-threatening ventricular arrhythmias and sudden death. QT duration correlates strongly with the risk of developing torsade de pointes, a form of ventricular tachycardia that can degenerate into ventricular fibrillation. Therefore, QT prolongation is a qualitative marker of proarrhythmic risk, and analysis of ventricular repolarization is therefore required for the approval of new drugs. To that end, the Thorough QT/QTc analysis evaluates QT interval prolongation to assess potential proarrhythmic effects. In addition, since diabetic patients have a higher risk to die from cardiovascular causes than individuals without diabetes, cardiovascular safety of the new antidiabetic drugs must be carefully evaluated in type 2 diabetic patients. These cardiovascular outcome trials reveal that some glucose-lowering drugs actually reduce cardiovascular risk. The mechanism of cardioprotection might involve a reduction of the risk of developing arrhythmia.
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Affiliation(s)
- Mónica Gallego
- Department of Physiology, Faculty of Pharmacy, University of the Basque Country UPV/EHU, Vitoria-Gasteiz, Spain
| | - Julián Zayas-Arrabal
- Department of Physiology, Faculty of Pharmacy, University of the Basque Country UPV/EHU, Vitoria-Gasteiz, Spain
| | - Amaia Alquiza
- Department of Physiology, Faculty of Pharmacy, University of the Basque Country UPV/EHU, Vitoria-Gasteiz, Spain
| | - Beatriz Apellaniz
- Department of Physiology, Faculty of Pharmacy, University of the Basque Country UPV/EHU, Vitoria-Gasteiz, Spain
| | - Oscar Casis
- Department of Physiology, Faculty of Pharmacy, University of the Basque Country UPV/EHU, Vitoria-Gasteiz, Spain
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7
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Lubberding AF, Pereira L, Xue J, Gottlieb LA, Matchkov VV, Gomez AM, Thomsen MB. Aberrant sinus node firing during β-adrenergic stimulation leads to cardiac arrhythmias in diabetic mice. Acta Physiol (Oxf) 2020; 229:e13444. [PMID: 31953990 DOI: 10.1111/apha.13444] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 12/25/2019] [Accepted: 01/13/2020] [Indexed: 01/08/2023]
Abstract
AIM Cardiovascular complications, including cardiac arrhythmias, result in high morbidity and mortality in patients with type-2 diabetes mellitus (T2DM). Clinical and experimental data suggest electrophysiological impairment of the natural pacemaker of the diabetic heart. The present study examined sinoatrial node (SAN) arrhythmias in a mouse model of T2DM and physiologically probed their underlying cause. METHODS Electrocardiograms were obtained from conscious diabetic db/db and lean control db/+ mice. In vivo SAN function was probed through pharmacological autonomic modulation with isoprenaline, atropine and carbachol. Blood pressure stability and heart rate variability (HRV) were evaluated. Intrinsic SAN function was evaluated through ex vivo imaging of spontaneous Ca2+ transients in isolated SAN preparations. RESULTS While lean control mice showed constant RR intervals during isoprenaline challenge, the diabetic mice experienced SAN arrhythmias with large RR fluctuations in a dose-dependent manner. These arrhythmias were completely abolished by atropine pre-treatment, while carbachol pretreatment significantly increased SAN arrhythmia frequency in the diabetic mice. Blood pressure and HRV were comparable in db/db and db/+ mice, suggesting that neither augmented baroreceptor feedback nor autonomic neuropathy is a likely arrhythmia mechanism. Cycle length response to isoprenaline was comparable in isolated SAN preparations from db/db and db/+ mice; however, Ca2+ spark frequency was significantly increased in db/db mice compared to db/+ at baseline and after isoprenaline. CONCLUSION Our results demonstrate a dysfunction of cardiac pacemaking in an animal model of T2DM upon challenge with a β-adrenergic agonist. Ex vivo, higher Ca2+ spark frequency is present in diabetic mice, which may be directly linked to in vivo arrhythmias.
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Affiliation(s)
- Anniek F. Lubberding
- Department of Biomedical Sciences Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
| | - Laetitia Pereira
- Université Paris‐Saclay Inserm UMR‐S 1180 Châtenay‐Malabry France
| | - Jianbin Xue
- Université Paris‐Saclay Inserm UMR‐S 1180 Châtenay‐Malabry France
| | - Lisa A. Gottlieb
- Department of Biomedical Sciences Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
| | | | - Ana M. Gomez
- Université Paris‐Saclay Inserm UMR‐S 1180 Châtenay‐Malabry France
| | - Morten B. Thomsen
- Department of Biomedical Sciences Faculty of Health and Medical Sciences University of Copenhagen Copenhagen Denmark
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8
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Grisanti LA. Diabetes and Arrhythmias: Pathophysiology, Mechanisms and Therapeutic Outcomes. Front Physiol 2018; 9:1669. [PMID: 30534081 PMCID: PMC6275303 DOI: 10.3389/fphys.2018.01669] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 11/06/2018] [Indexed: 12/17/2022] Open
Abstract
The prevalence of diabetes is rapidly increasing and closely associated with cardiovascular morbidity and mortality. While the major cardiovascular complication associated with diabetes is coronary artery disease, it is becoming increasingly apparent that diabetes impacts the electrical conduction system in the heart, resulting in atrial fibrillation, and ventricular arrhythmias. The relationship between diabetes and arrhythmias is complex and multifactorial including autonomic dysfunction, atrial and ventricular remodeling and molecular alterations. This review will provide a comprehensive overview of the link between diabetes and arrhythmias with insight into the common molecular mechanisms, structural alterations and therapeutic outcomes.
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Affiliation(s)
- Laurel A Grisanti
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, United States
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9
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Howarth FC, Qureshi MA, Jayaprakash P, Parekh K, Oz M, Dobrzynski H, Adrian TE. The Pattern of mRNA Expression Is Changed in Sinoatrial Node from Goto-Kakizaki Type 2 Diabetic Rat Heart. J Diabetes Res 2018; 2018:8454078. [PMID: 30246030 PMCID: PMC6139199 DOI: 10.1155/2018/8454078] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Revised: 07/16/2018] [Accepted: 08/12/2018] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND In vivo experiments in Goto-Kakizaki (GK) type 2 diabetic rats have demonstrated reductions in heart rate from a young age. The expression of genes encoding more than 70 proteins that are associated with the generation and conduction of electrical activity in the GK sinoatrial node (SAN) have been evaluated to further clarify the molecular basis of the low heart rate. MATERIALS AND METHODS Heart rate and expression of genes were evaluated with an extracellular electrode and real-time RT-PCR, respectively. Rats aged 12-13 months were employed in these experiments. RESULTS Isolated spontaneous heart rate was reduced in GK heart (161 ± 12 bpm) compared to controls (229 ± 11 bpm). There were many differences in expression of mRNA, and some of these differences were of particular interest. Compared to control SAN, expression of some genes were downregulated in GK-SAN: gap junction, Gja1 (Cx43), Gja5 (Cx40), Gjc1 (Cx45), and Gjd3 (Cx31.9); cell membrane transport, Trpc1 (TRPC1) and Trpc6 (TRPC6); hyperpolarization-activated cyclic nucleotide-gated channels, Hcn1 (HCN1) and Hcn4 (HCN4); calcium channels, Cacna1d (Cav1.3), Cacna1g (Cav3.1), Cacna1h (Cav3.2), Cacna2d1 (Cavα2δ1), Cacna2d3 (Cavα2δ3), and Cacng4 (Cav γ 4); and potassium channels, Kcna2 (Kv1.2), Kcna4 (Kv1.4), Kcna5 (Kv1.5), Kcnb1 (Kv2.1), Kcnd3 (Kv4.3), Kcnj2 (Kir2.1), Kcnk1 (TWIK1), Kcnk5 (K2P5.1), Kcnk6 (TWIK2), and Kcnn2 (SK2) whilst others were upregulated in GK-SAN: Ryr2 (RYR2) and Nppb (BNP). CONCLUSIONS This study provides new insight into the changing expression of genes in the sinoatrial node of diabetic heart.
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MESH Headings
- Action Potentials
- Animals
- Arrhythmias, Cardiac/etiology
- Arrhythmias, Cardiac/genetics
- Arrhythmias, Cardiac/metabolism
- Arrhythmias, Cardiac/physiopathology
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Diabetic Cardiomyopathies/etiology
- Diabetic Cardiomyopathies/genetics
- Diabetic Cardiomyopathies/metabolism
- Diabetic Cardiomyopathies/physiopathology
- Disease Models, Animal
- Gene Expression Regulation
- Heart Rate/genetics
- Isolated Heart Preparation
- Male
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Rats, Wistar
- Sinoatrial Node/metabolism
- Sinoatrial Node/physiopathology
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Affiliation(s)
- F. C. Howarth
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - M. A. Qureshi
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - P. Jayaprakash
- Department of Pharmacology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - K. Parekh
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - M. Oz
- Department of Pharmacology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - H. Dobrzynski
- Cardiovascular Sciences, University of Manchester, Manchester, UK
| | - T. E. Adrian
- Department of Basic Medical Sciences, Mohammed Bin Rashid University of Medicine & Health Sciences, Dubai, UAE
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10
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Russell J, Du Toit EF, Peart JN, Patel HH, Headrick JP. Myocyte membrane and microdomain modifications in diabetes: determinants of ischemic tolerance and cardioprotection. Cardiovasc Diabetol 2017; 16:155. [PMID: 29202762 PMCID: PMC5716308 DOI: 10.1186/s12933-017-0638-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 11/22/2017] [Indexed: 02/06/2023] Open
Abstract
Cardiovascular disease, predominantly ischemic heart disease (IHD), is the leading cause of death in diabetes mellitus (DM). In addition to eliciting cardiomyopathy, DM induces a ‘wicked triumvirate’: (i) increasing the risk and incidence of IHD and myocardial ischemia; (ii) decreasing myocardial tolerance to ischemia–reperfusion (I–R) injury; and (iii) inhibiting or eliminating responses to cardioprotective stimuli. Changes in ischemic tolerance and cardioprotective signaling may contribute to substantially higher mortality and morbidity following ischemic insult in DM patients. Among the diverse mechanisms implicated in diabetic impairment of ischemic tolerance and cardioprotection, changes in sarcolemmal makeup may play an overarching role and are considered in detail in the current review. Observations predominantly in animal models reveal DM-dependent changes in membrane lipid composition (cholesterol and triglyceride accumulation, fatty acid saturation vs. reduced desaturation, phospholipid remodeling) that contribute to modulation of caveolar domains, gap junctions and T-tubules. These modifications influence sarcolemmal biophysical properties, receptor and phospholipid signaling, ion channel and transporter functions, contributing to contractile and electrophysiological dysfunction, cardiomyopathy, ischemic intolerance and suppression of protective signaling. A better understanding of these sarcolemmal abnormalities in types I and II DM (T1DM, T2DM) can inform approaches to limiting cardiomyopathy, associated IHD and their consequences. Key knowledge gaps include details of sarcolemmal changes in models of T2DM, temporal patterns of lipid, microdomain and T-tubule changes during disease development, and the precise impacts of these diverse sarcolemmal modifications. Importantly, exercise, dietary, pharmacological and gene approaches have potential for improving sarcolemmal makeup, and thus myocyte function and stress-resistance in this ubiquitous metabolic disorder.
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Affiliation(s)
- Jake Russell
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia
| | - Eugene F Du Toit
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia
| | - Jason N Peart
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia
| | - Hemal H Patel
- VA San Diego Healthcare System and Department of Anesthesiology, University of California San Diego, San Diego, USA
| | - John P Headrick
- Menzies Health Institute Queensland, Griffith University, Southport, QLD, Australia. .,School of Medical Science, Griffith University, Southport, QLD, 4217, Australia.
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11
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Howarth FC, Parekh K, Jayaprakash P, Inbaraj ES, Oz M, Dobrzynski H, Adrian TE. Altered profile of mRNA expression in atrioventricular node of streptozotocin‑induced diabetic rats. Mol Med Rep 2017; 16:3720-3730. [PMID: 28731153 PMCID: PMC5646948 DOI: 10.3892/mmr.2017.7038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 07/11/2017] [Indexed: 02/07/2023] Open
Abstract
Prolonged action potential duration, reduced action potential firing rate, upstroke velocity and rate of diastolic depolarization have been demonstrated in atrioventricular node (AVN) cells from streptozotocin (STZ)-induced diabetic rats. To further clarify the molecular basis of these electrical disturbances, the mRNA profiles encoding a variety of proteins associated with the generation and conduction of electrical activity in the AVN, were evaluated in the STZ-induced diabetic rat heart. Expression of mRNA was measured in AVN biopsies using reverse transcription-quantitative polymerase chain reaction techniques. Notable differences in mRNA expression included upregulation of genes encoding membrane and intracellular Ca2+ transport, including solute carrier family 8 member A1, transient receptor potential channel 1, ryanodine receptor 2/3, hyperpolarization-activated cyclic-nucleotide 2 and 3, calcium channel voltage-dependent, β2 subunit and sodium channels 3a, 4a, 7a and 3b. In addition to this, potassium channels potassium voltage-gated channel subfamily A member 4, potassium channel calcium activated intermediate/small conductance subfamily N α member 2, potassium voltage-gated channel subfamily J members 3, 5, and 11, potassium channel subfamily K members 1, 2, 3 and natriuretic peptide B (BNP) were upregulated in AVN of STZ heart, compared with controls. Alterations in gene expression were associated with upregulation of various proteins including the inwardly rectifying, potassium channel Kir3.4, NCX1 and BNP. The present study demonstrated notable differences in the profile of mRNA encoding proteins associated with the generation, conduction and regulation of electrical signals in the AVN of the STZ-induced diabetic rat heart. These data will provide a basis for a substantial range of future studies to investigate whether variations in mRNA translate into alterations in electrophysiological function.
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Affiliation(s)
- Frank Christopher Howarth
- Department of Physiology, College of Medicine and Health Sciences, UAE University, Al Ain 17666, United Arab Emirates
| | - Khatija Parekh
- Department of Physiology, College of Medicine and Health Sciences, UAE University, Al Ain 17666, United Arab Emirates
| | - Petrilla Jayaprakash
- Department of Physiology, College of Medicine and Health Sciences, UAE University, Al Ain 17666, United Arab Emirates
| | - Edward Samuel Inbaraj
- Department of Physiology, College of Medicine and Health Sciences, UAE University, Al Ain 17666, United Arab Emirates
| | - Murat Oz
- Department of Pharmacology, College of Medicine and Health Sciences, UAE University, Al Ain 17666, United Arab Emirates
| | - Halina Dobrzynski
- Institute of Cardiovascular Sciences, University of Manchester, Manchester M13 9NT, United Kingdom
| | - Thomas Edward Adrian
- Department of Physiology, College of Medicine and Health Sciences, UAE University, Al Ain 17666, United Arab Emirates
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12
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Wang GY, Bi YG, Liu XD, Han JF, Wei M, Zhang QY. Upregulation of connexin 43 and apoptosis‑associated protein expression by high glucose in H9c2 cells was improved by resveratrol via the autophagy signaling pathway. Mol Med Rep 2017; 16:3262-3268. [PMID: 28713934 PMCID: PMC5547968 DOI: 10.3892/mmr.2017.6953] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 05/05/2017] [Indexed: 12/22/2022] Open
Abstract
The expression of connexin43 (Cx43) protein and the apoptotic rate of cardiomyocytes may be regulated by autophagy and associated with diabetic cardiomyopathy. It is possible that the beneficial effect of resveratrol on diabetic cardiomyocytes occurs via the autophagy pathway. However, it remains to be elucidated whether resveratrol treatment may attenuate the hyperglycemia-induced remodeling of Cx43 and apoptosis through the regulation of autophagy. H9c2 cardiac cells were incubated with 5.5 and 25 mM glucose, 25 mM glucose with chloroquine (50 µM), and 25 mM glucose with or without resveratrol (10, 25 µM) for 24 h. H9c2 cells were also incubated with 25 µM resveratrol in the presence of chloroquine (50 µM). Cell viability was determined using an MTT cell survival assay. Cytotoxicity was determined by quantification of the release of lactate dehydrogenase. The expression of Cx43, autophagic maker proteins [Beclin-1, p62 and microtubule-associated protein 1 light chain 3 (LC3)], apoptosis maker proteins (B-cell lymphoma-2 and Bcl-2 associated X protein), AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) were determined using western blotting. Resveratrol treatment led to reduced Cx43 expression levels compared with the 25 mM glucose treatment and significantly reduced the expression of apoptosis-associated proteins in H9c2 cells under hyperglycemic conditions. Autophagy was increased as indicated by the upregulation of Beclin-1 and p62 expression and the reduced LC3-II/LC3-I ratio. AMPK expression was increased, whereas mTOR expression was reduced in the resveratrol treatment groups. Treatment with chloroquine reversed effect of resveratrol. In conclusion, administration resveratrol may protect H9c2 cells against hyperglycemia-induced Cx43 upregulation and apoptosis, which may be mediated through the induction of the autophagy signaling pathway.
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Affiliation(s)
- Guang-Yu Wang
- Department of Cardiology, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai 200233, P.R. China
| | - Ya-Guang Bi
- Department of Cardiology, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai 200233, P.R. China
| | - Xiang-Dong Liu
- Department of Cardiology, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai 200233, P.R. China
| | - Jun-Feng Han
- Department of Endocrinology and Metabolism, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai 200233, P.R. China
| | - Meng Wei
- Department of Cardiology, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai 200233, P.R. China
| | - Qing-Yong Zhang
- Department of Cardiology, Shanghai Sixth People's Hospital, Shanghai Jiao Tong University, Shanghai 200233, P.R. China
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13
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Roy S, Jiang JX, Li AF, Kim D. Connexin channel and its role in diabetic retinopathy. Prog Retin Eye Res 2017; 61:35-59. [PMID: 28602949 DOI: 10.1016/j.preteyeres.2017.06.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 05/30/2017] [Accepted: 06/02/2017] [Indexed: 12/18/2022]
Abstract
Diabetic retinopathy is the leading cause of blindness in the working age population. Unfortunately, there is no cure for this devastating ocular complication. The early stage of diabetic retinopathy is characterized by the loss of various cell types in the retina, namely endothelial cells and pericytes. As the disease progresses, vascular leakage, a clinical hallmark of diabetic retinopathy, becomes evident and may eventually lead to diabetic macular edema, the most common cause of vision loss in diabetic retinopathy. Substantial evidence indicates that the disruption of connexin-mediated cellular communication plays a critical role in the pathogenesis of diabetic retinopathy. Yet, it is unclear how altered communication via connexin channel mediated cell-to-cell and cell-to-extracellular microenvironment is linked to the development of diabetic retinopathy. Recent observations suggest the possibility that connexin hemichannels may play a role in the pathogenesis of diabetic retinopathy by allowing communication between cells and the microenvironment. Interestingly, recent studies suggest that connexin channels may be involved in regulating retinal vascular permeability. These cellular events are coordinated at least in part via connexin-mediated intercellular communication and the maintenance of retinal vascular homeostasis. This review highlights the effect of high glucose and diabetic condition on connexin channels and their impact on the development of diabetic retinopathy.
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Affiliation(s)
- Sayon Roy
- Departments of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States.
| | - Jean X Jiang
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, United States
| | - An-Fei Li
- Department of Ophthalmology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan
| | - Dongjoon Kim
- Departments of Medicine and Ophthalmology, Boston University School of Medicine, Boston, MA, United States
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Ferdous Z, Qureshi MA, Jayaprakash P, Parekh K, John A, Oz M, Raza H, Dobrzynski H, Adrian TE, Howarth FC. Different Profile of mRNA Expression in Sinoatrial Node from Streptozotocin-Induced Diabetic Rat. PLoS One 2016; 11:e0153934. [PMID: 27096430 PMCID: PMC4838258 DOI: 10.1371/journal.pone.0153934] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 04/06/2016] [Indexed: 11/30/2022] Open
Abstract
Background Experiments in isolated perfused heart have shown that heart rate is lower and sinoatrial node (SAN) action potential duration is longer in streptozotocin (STZ)–induced diabetic rat compared to controls. In sino-atrial preparations the pacemaker cycle length and sino-atrial conduction time are prolonged in STZ heart. To further clarify the molecular basis of electrical disturbances in the diabetic heart the profile of mRNA encoding a wide variety of proteins associated with the generation and transmission of electrical activity has been evaluated in the SAN of STZ-induced diabetic rat heart. Methodology/Principal Findings Heart rate was measured in isolated perfused heart with an extracellular suction electrode. Expression of mRNA encoding a variety of intercellular proteins, intracellular Ca2+-transport and regulatory proteins, cell membrane transport proteins and calcium, sodium and potassium channel proteins were measured in SAN and right atrial (RA) biopsies using real-time reverse transcription polymerase chain reaction techniques. Heart rate was lower in STZ (203±7 bpm) compared to control (239±11 bpm) rat. Among many differences in the profile of mRNA there are some worthy of particular emphasis. Expression of genes encoding some proteins were significantly downregulated in STZ-SAN: calcium channel, Cacng4 (7-fold); potassium channel, Kcnd2 whilst genes encoding some other proteins were significantly upregulated in STZ-SAN: gap junction, Gjc1; cell membrane transport, Slc8a1, Trpc1, Trpc6 (4-fold); intracellular Ca2+-transport, Ryr3; calcium channel Cacna1g, Cacna1h, Cacnb3; potassium channels, Kcnj5, Kcnk3 and natriuretic peptides, Nppa (5-fold) and Nppb (7-fold). Conclusions/Significance Collectively, this study has demonstrated differences in the profile of mRNA encoding a variety of proteins that are associated with the generation, conduction and regulation of electrical signals in the SAN of STZ-induced diabetic rat heart. Data from this study will provide a basis for a substantial range of future studies to investigate whether these changes in mRNA translate into changes in electrophysiological function.
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Affiliation(s)
- Zannatul Ferdous
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - Muhammad Anwar Qureshi
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - Petrilla Jayaprakash
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - Khatija Parekh
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - Annie John
- Department of Biochemistry, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - Murat Oz
- Department of Pharmacology, College of Medicine & Health Sciences, UAE University, Al AIn, UAE
| | - Haider Raza
- Department of Biochemistry, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
| | - Halina Dobrzynski
- Institute of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Thomas Edward Adrian
- Department of Physiology, College of Medicine & Health Sciences, UAE University, Al Ain, UAE
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15
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Tse G, Lai ETH, Tse V, Yeo JM. Molecular and Electrophysiological Mechanisms Underlying Cardiac Arrhythmogenesis in Diabetes Mellitus. J Diabetes Res 2016; 2016:2848759. [PMID: 27642609 PMCID: PMC5011530 DOI: 10.1155/2016/2848759] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 04/28/2016] [Indexed: 01/11/2023] Open
Abstract
Diabetes is a common endocrine disorder with an ever increasing prevalence globally, placing significant burdens on our healthcare systems. It is associated with significant cardiovascular morbidities. One of the mechanisms by which it causes death is increasing the risk of cardiac arrhythmias. The aim of this article is to review the cardiac (ion channel abnormalities, electrophysiological and structural remodelling) and extracardiac factors (neural pathway remodelling) responsible for cardiac arrhythmogenesis in diabetes. It is concluded by an outline of molecular targets for future antiarrhythmic therapy for the diabetic population.
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Affiliation(s)
- Gary Tse
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Shatin, Hong Kong
- *Gary Tse:
| | - Eric Tsz Him Lai
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, University of Hong Kong, Hong Kong
| | - Vivian Tse
- Department of Physiology, McGill University, Montreal, QC, Canada H3G 1Y6
| | - Jie Ming Yeo
- School of Medicine, Imperial College London, London SW7 2AZ, UK
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16
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Yuill KH, Al Kury LT, Howarth FC. Characterization of L-type calcium channel activity in atrioventricular nodal myocytes from rats with streptozotocin-induced Diabetes mellitus. Physiol Rep 2015; 3:3/11/e12632. [PMID: 26603460 PMCID: PMC4673653 DOI: 10.14814/phy2.12632] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 10/26/2015] [Indexed: 12/12/2022] Open
Abstract
Cardiovascular complications are common in patients with Diabetes mellitus (DM). In addition to changes in cardiac muscle inotropy, electrical abnormalities are also commonly observed in these patients. We have previously shown that spontaneous cellular electrical activity is altered in atrioventricular nodal (AVN) myocytes, isolated from the streptozotocin (STZ) rat model of type-1 DM. In this study, utilizing the same model, we have characterized the changes in L-type calcium channel activity in single AVN myocytes. Ionic currents were recorded from AVN myocytes isolated from the hearts of control rats and from those with STZ-induced diabetes. Patch-clamp recordings were used to assess the changes in cellular electrical activity in individual myocytes. Type-1 DM significantly altered the cellular characteristics of L-type calcium current. A reduction in peak ICaL density was observed, with no corresponding changes in the activation parameters of the current. L-type calcium channel current also exhibited faster time-dependent inactivation in AVN myocytes from diabetic rats. A negative shift in the voltage dependence of inactivation was also evident, and a slowing of restitution parameters. These findings demonstrate that experimentally induced type-1 DM significantly alters AVN L-type calcium channel cellular electrophysiology. These changes in ion channel activity may contribute to the abnormalities in cardiac electrical function that are associated with high mortality levels in patients with DM.
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Affiliation(s)
- Kathryn H Yuill
- Department of Biological, Biomedical and Analytical Sciences, University of the West of England, Bristol, United Kingdom
| | - Lina T Al Kury
- College of Sustainability Sciences and Humanities, Zayed University, Abu Dhabi, UAE
| | - Frank Christopher Howarth
- Department of Physiology, Faculty of Medicine & Health Sciences, United Arab Emirates University, PO Box 17666, Al Ain, UAE
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17
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Joshi MS, Mihm MJ, Cook AC, Schanbacher BL, Bauer JA. Alterations in connexin 43 during diabetic cardiomyopathy: competition of tyrosine nitration versus phosphorylation. J Diabetes 2015; 7:250-259. [PMID: 24796789 PMCID: PMC4221578 DOI: 10.1111/1753-0407.12164] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 04/14/2014] [Accepted: 04/27/2014] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Cardiac conduction abnormalities are observed early in the progression of type 1 diabetes (T1D), but the mechanism(s) involved are undefined. Connexin 43, a critical component of ventricular gap junctions, depends on tyrosine phosphorylation status to modulate channel conductance; changes in connexin 43 content, distribution, and/or phosphorylation status may be involved in cardiac rhythm disturbances. We tested the hypothesis that cardiac content and/or distribution of connexin 43 is altered in a rat model of T1D cardiomyopathy, investigating a mechanistic role for tyrosine. METHODS Electrocardiographic analyses were conducted during the progression of diabetic cardiomyopathy in rats dosed with streptozotocin (STZ; 65 mg/kg) 3, 7, and 35 days after the induction of diabetes. Following functional analyses, we conducted immunohistochemical and immunoprecipitation studies to assess alterations in connexin 43. RESULTS There was significant evidence of ventricular conduction abnormalities (QRS complex, Q-T interval) as early as 7 days after STZ, persisting throughout the study. Connexin 43 levels were increased 7 days after STZ and remained elevated throughout the study. Connexin 40 content was unchanged relative to controls throughout the study. Changes in connexin 43 distribution were also observed: connexin 43 staining was dispersed from myocyte short axis junctions. Connexin 43 tyrosine phosphorylation declined during the progression of diabetes, with concurrent increases in tyrosine nitration. CONCLUSIONS The data suggest that changes in connexin 43 content and distribution occur during experimental diabetes and likely contribute to alterations in cardiac function, and that oxidative modification of tyrosine-mediated signaling may play a mechanistic role.
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Affiliation(s)
- Mandar S Joshi
- Baker IDI Heart and Diabetes Institute, 75 Commercial Road, Melbourne, Victoria 3150, Australia
- Department of Medicine, Central Clinical School, Monash University, Melbourne, Australia
- University of Kentucky College of Medicine, Department of Pediatrics, Lexington KY 40536, USA
| | - Michael J Mihm
- The Ohio State University College of Pharmacy, 500 W 12 Ave, Columbus, OH 43210, USA
| | - Angela C Cook
- The Ohio State University College of Pharmacy, 500 W 12 Ave, Columbus, OH 43210, USA
| | - Brandon L Schanbacher
- Centre for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
- University of Kentucky College of Medicine, Department of Pediatrics, Lexington KY 40536, USA
| | - John Anthony Bauer
- Centre for Perinatal Research, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205, USA
- University of Kentucky College of Medicine, Department of Pediatrics, Lexington KY 40536, USA
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18
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Affiliation(s)
- Gwilym M Morris
- Institute of Cardiovascular Sciences, University of Manchester, Core Technology Facility
- Department of Cardiology, The Royal Melbourne Hospital
| | - Jonathan M Kalman
- Department of Cardiology, The Royal Melbourne Hospital
- Department of Medicine, Melbourne University
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19
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Wu X, Huang W, Luo G, Alain LA. Hypoxia induces connexin 43 dysregulation by modulating matrix metalloproteinases via MAPK signaling. Mol Cell Biochem 2013; 384:155-62. [PMID: 24002703 PMCID: PMC3825321 DOI: 10.1007/s11010-013-1793-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 08/23/2013] [Indexed: 11/30/2022]
Abstract
Connexin 43 (Cx43) is a major structural protein found in the gap junctions of the ventricular myocardium and a major determinant of its electrical properties. The effects of matrix metalloproteinases (MMPs), the mitogen-activated protein kinase (MAPK) signaling pathway, transcription factor NF-kB, and activator protein-1 (AP-1)/c-Jun on the regulation of Cx43 gene expression in H9c2 cardiomyocytes were assessed. The MAPK signaling pathway (MEK/ERK1/2 and PI3K) and transcription factors NF-kB and AP-1/c-Jun were inhibited, then Cx43 expression was assessed using Western blot analysis, and MMP-9 activity was assessed using gelatin zymography. Hypoxia decreased the Cx43 protein level by approximately 30-50 %. Doxycycline (10 μg/mL), an inhibitor of MMP, markedly attenuated the hypoxia-induced downregulation of Cx43 protein expression at 6 h. The hypoxia-induced decrease in Cx43 protein expression was significantly reversed by U0126 (10 μM), a MEK/ERK1/2 inhibitor, at 6 and 12 h; LY294002 (30 μM), a PI3K inhibitor, downregulated Cx43 expression. Hypoxia-induced MMP-9 activation was inhibited by treatment with LY294002, U0126, and, most especially, U0126. JSH-23 (30 μM), an NF-kB inhibitor, and SP600125 (10 μM), an AP-1/c-Jun inhibitor, attenuated the loss of Cx43. These results suggest that MAPK signaling and the activities NF-kB and MMPs play an important roles in the regulation of Cx43 expression.
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Affiliation(s)
- Xianghong Wu
- Department of Cardiology, First Affiliated Hospital, Guangxi Medical University, Nanning, People's Republic of China
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20
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Abstract
Cell-to-cell interactions via gap junctional communication and connexon hemichannels are involved in the pathogenesis of diabetes. Gap junctions are highly specialized transmembrane structures that are formed by connexon hemichannels, which are further assembled from proteins called “connexins.” In this paper, we discuss current knowledge about connexins in diabetes. We also discuss mechanisms of connexin influence and the role of individual connexins in various tissues and how these are affected in diabetes. Connexins may be a future target by both genetic and pharmacological approaches to develop treatments for the treatment of diabetes and its complications.
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21
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Becker DL, Thrasivoulou C, Phillips ARJ. Connexins in wound healing; perspectives in diabetic patients. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:2068-75. [PMID: 22155211 DOI: 10.1016/j.bbamem.2011.11.017] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 11/07/2011] [Accepted: 11/18/2011] [Indexed: 11/19/2022]
Abstract
Skin lesions are common events and we have evolved to rapidly heal them in order to maintain homeostasis and prevent infection and sepsis. Most acute wounds heal without issue, but as we get older our bodies become compromised by poor blood circulation and conditions such as diabetes, leading to slower healing. This can result in stalled or hard-to-heal chronic wounds. Currently about 2% of the Western population develop a chronic wound and this figure will rise as the population ages and diabetes becomes more prevalent [1]. Patient morbidity and quality of life are profoundly altered by chronic wounds [2]. Unfortunately a significant proportion of these chronic wounds fail to respond to conventional treatment and can result in amputation of the lower limb. Life quality and expectancy following amputation is severely reduced. These hard to heal wounds also represent a growing economic burden on Western society with published estimates of costs to healthcare services in the region of $25B annually [3]. There exists a growing need for specific and effective therapeutic agents to improve healing in these wounds. In recent years the gap junction protein Cx43 has been shown to play a pivotal role early on in the acute wound healing process at a number of different levels [4-7]. Conversely, abnormal expression of Cx43 in wound edge keratinocytes was shown to underlie the poor rate of healing in diabetic rats, and targeting its expression with an antisense gel restored normal healing rates [8]. The presence of Cx43 in the wound edge keratinocytes of human chronic wounds has also been reported [9]. Abnormal Cx43 biology may underlie the poor healing of human chronic wounds and be amenable therapeutic intervention [7]. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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Affiliation(s)
- David L Becker
- Department of Cell and Developmental Biology, University College, London, WC1E 6BT, UK.
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22
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Alteration of the cardiac sympathetic innervation is modulated by duration of diabetes in female rats. EXPERIMENTAL DIABETES RESEARCH 2011; 2011:835932. [PMID: 21792353 PMCID: PMC3142701 DOI: 10.1155/2011/835932] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 05/13/2011] [Indexed: 12/02/2022]
Abstract
To evaluate the sympathetic innervation of the female diabetic heart, resting heart rate and sympathetic tone were assessed in vivo, and effect of tyramine on spontaneous beating rate, norepinephrine atrial concentrations, uptake, and release were determined in vitro in streptozotocin- (STZ-) treated rats and respective controls aged 3 months to 2 years. Resting bradycardia, decreased sympathetic tone, deceleration of spontaneous beating rate, and slightly declining carrier-mediated, but preserved exocytotic norepinephrine release from the atria were found in younger diabetic rats while the reactivity of the right atria to tyramine was not affected with age and disease duration. Diabetic two-year-old animals displayed symptoms of partial spontaneous recovery including normoglycemia, increased plasma insulin concentrations, fully recovered sympathetic tone, but putative change, in releasable norepinephrine tissue stores. Our data suggested that female diabetic heart exposed to long-lasting diabetic conditions seems to be more resistant to alteration in sympathetic innervation than the male one.
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23
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Monfredi O, Dobrzynski H, Mondal T, Boyett MR, Morris GM. The anatomy and physiology of the sinoatrial node--a contemporary review. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2010; 33:1392-406. [PMID: 20946278 DOI: 10.1111/j.1540-8159.2010.02838.x] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The sinoatrial node is the primary pacemaker of the heart. Nodal dysfunction with aging, heart failure, atrial fibrillation, and even endurance athletic training can lead to a wide variety of pathological clinical syndromes. Recent work utilizing molecular markers to map the extent of the node, along with the delineation of a novel paranodal area intermediate in characteristics between the node and the surrounding atrial muscle, has shown that pacemaker tissue is more widely spread in the right atrium than previously appreciated. This can explain the phenomenon of a "wandering pacemaker" and concomitant changes in the P-wave morphology. Extensive knowledge now exists regarding the molecular architecture of the node (in particular, the expression of ion channels) and how this relates to pacemaking. This review is an up-to-date summary of the current state of our appreciation of the above topics.
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Affiliation(s)
- Oliver Monfredi
- Cardiovascular Medicine, Faculty of Medical and Human Sciences, University of Manchester, Core Technology Facility, Manchester, United Kingdom
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24
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A large-scale genome-wide association study of Asian populations uncovers genetic factors influencing eight quantitative traits. Nat Genet 2009; 41:527-34. [PMID: 19396169 DOI: 10.1038/ng.357] [Citation(s) in RCA: 786] [Impact Index Per Article: 52.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Accepted: 02/12/2009] [Indexed: 11/08/2022]
Abstract
To identify genetic factors influencing quantitative traits of biomedical importance, we conducted a genome-wide association study in 8,842 samples from population-based cohorts recruited in Korea. For height and body mass index, most variants detected overlapped those reported in European samples. For the other traits examined, replication of promising GWAS signals in 7,861 independent Korean samples identified six previously unknown loci. For pulse rate, signals reaching genome-wide significance mapped to chromosomes 1q32 (rs12731740, P = 2.9 x 10(-9)) and 6q22 (rs12110693, P = 1.6 x 10(-9)), with the latter approximately 400 kb from the coding sequence of GJA1. For systolic blood pressure, the most compelling association involved chromosome 12q21 and variants near the ATP2B1 gene (rs17249754, P = 1.3 x 10(-7)). For waist-hip ratio, variants on chromosome 12q24 (rs2074356, P = 7.8 x 10(-12)) showed convincing associations, although no regional transcript has strong biological candidacy. Finally, we identified two loci influencing bone mineral density at multiple sites. On chromosome 7q31, rs7776725 (within the FAM3C gene) was associated with bone density at the radius (P = 1.0 x 10(-11)), tibia (P = 1.6 x 10(-6)) and heel (P = 1.9 x 10(-10)). On chromosome 7p14, rs1721400 (mapping close to SFRP4, a frizzled protein gene) showed consistent associations at the same three sites (P = 2.2 x 10(-3), P = 1.4 x 10(-7) and P = 6.0 x 10(-4), respectively). This large-scale GWA analysis of well-characterized Korean population-based samples highlights previously unknown biological pathways.
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Howarth FC, Jacobson M, Qureshi MA, Shafiullah M, Hameed RS, Zilahi E, Al Haj A, Nowotny N, Adeghate E. Altered gene expression may underlie prolonged duration of the QT interval and ventricular action potential in streptozotocin-induced diabetic rat heart. Mol Cell Biochem 2009; 328:57-65. [DOI: 10.1007/s11010-009-0074-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2008] [Accepted: 02/24/2009] [Indexed: 12/16/2022]
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Makino A, Platoshyn O, Suarez J, Yuan JXJ, Dillmann WH. Downregulation of connexin40 is associated with coronary endothelial cell dysfunction in streptozotocin-induced diabetic mice. Am J Physiol Cell Physiol 2008; 295:C221-30. [PMID: 18463230 PMCID: PMC2493564 DOI: 10.1152/ajpcell.00433.2007] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2007] [Accepted: 05/05/2008] [Indexed: 01/31/2023]
Abstract
Vascular endothelial cells (ECs) play a major role in regulating vascular tone and in revascularization. There is increasing evidence showing endothelial dysfunction in diabetes, although little is known about the contribution of connexins (Cxs) to vascular complications in the diabetic heart. This study was designed to investigate the role of Cxs in coronary endothelial dysfunction in diabetic mice. Coronary ECs isolated from diabetic mice exhibit lowered protein levels of Cx37 and Cx40 (but not Cx43) and a loss of gap junction intercellular communication (GJIC). Vasodilatation induced by the assumed contribution of EC-dependent hyperpolarization was significantly reduced in the diabetic coronary artery (CA). Cx40-specific inhibitory peptide (40)GAP27 strongly attenuated endothelium-dependent relaxation in diabetic CA at the concentration that does not affect the relaxation in control CA, suggesting that the total amount of Cx40 is lower in diabetic CA than in control CA. In diabetic mice, coronary capillary density was significantly decreased in vivo. In vitro, GJIC inhibitor attenuated the ability of EC capillary network formation. High-glucose treatment caused a decrease in Cx40 protein expression in ECs and impaired endothelial capillary network formation, which was restored by Cx40 overexpression. Furthermore, we found that the hyperglycemia-induced decrease in Cx40 was associated with inhibited protein expression of Sp1, a transcriptional factor that regulates Cx40 expression. These data suggest that downregulation of Cx40 protein expression and resultant inhibition of GJIC contribute to coronary vascular dysfunction in diabetes.
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Affiliation(s)
- Ayako Makino
- Division of Endocrinology and Metabolism, Department of Medicine, University of California San Diego, La Jolla, CA 92093-0618, USA
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