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Schenkl C, Heyne E, Doenst T, Schulze PC, Nguyen TD. Targeting Mitochondrial Metabolism to Save the Failing Heart. Life (Basel) 2023; 13:life13041027. [PMID: 37109556 PMCID: PMC10143865 DOI: 10.3390/life13041027] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/28/2023] [Accepted: 04/11/2023] [Indexed: 04/29/2023] Open
Abstract
Despite considerable progress in treating cardiac disorders, the prevalence of heart failure (HF) keeps growing, making it a global medical and economic burden. HF is characterized by profound metabolic remodeling, which mostly occurs in the mitochondria. Although it is well established that the failing heart is energy-deficient, the role of mitochondria in the pathophysiology of HF extends beyond the energetic aspects. Changes in substrate oxidation, tricarboxylic acid cycle and the respiratory chain have emerged as key players in regulating myocardial energy homeostasis, Ca2+ handling, oxidative stress and inflammation. This work aims to highlight metabolic alterations in the mitochondria and their far-reaching effects on the pathophysiology of HF. Based on this knowledge, we will also discuss potential metabolic approaches to improve cardiac function.
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Affiliation(s)
- Christina Schenkl
- Department of Cardiothoracic Surgery, Jena University Hospital, Friedrich Schiller University Jena, Am Klinikum 1, 07747 Jena, Germany
| | - Estelle Heyne
- Department of Cardiothoracic Surgery, Jena University Hospital, Friedrich Schiller University Jena, Am Klinikum 1, 07747 Jena, Germany
| | - Torsten Doenst
- Department of Cardiothoracic Surgery, Jena University Hospital, Friedrich Schiller University Jena, Am Klinikum 1, 07747 Jena, Germany
| | - Paul Christian Schulze
- Department of Medicine I (Cardiology, Angiology, Critical Care Medicine), Jena University Hospital, Friedrich Schiller University Jena, Am Klinikum 1, 07747 Jena, Germany
| | - Tien Dung Nguyen
- Department of Medicine I (Cardiology, Angiology, Critical Care Medicine), Jena University Hospital, Friedrich Schiller University Jena, Am Klinikum 1, 07747 Jena, Germany
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2
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Dhalla NS, Elimban V, Bartekova M, Adameova A. Involvement of Oxidative Stress in the Development of Subcellular Defects and Heart Disease. Biomedicines 2022; 10:biomedicines10020393. [PMID: 35203602 PMCID: PMC8962363 DOI: 10.3390/biomedicines10020393] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/01/2022] [Accepted: 02/02/2022] [Indexed: 02/01/2023] Open
Abstract
It is now well known that oxidative stress promotes lipid peroxidation, protein oxidation, activation of proteases, fragmentation of DNA and alteration in gene expression for producing myocardial cell damage, whereas its actions for the induction of fibrosis, necrosis and apoptosis are considered to result in the loss of cardiomyocytes in different types of heart disease. The present article is focused on the discussion concerning the generation and implications of oxidative stress from various sources such as defective mitochondrial electron transport and enzymatic reactions mainly due to the activation of NADPH oxidase, nitric oxide synthase and monoamine oxidase in diseased myocardium. Oxidative stress has been reported to promote excessive entry of Ca2+ due to increased permeability of the sarcolemmal membrane as well as depressions of Na+-K+ ATPase and Na+-Ca2+ exchange systems, which are considered to increase the intracellular of Ca2+. In addition, marked changes in the ryanodine receptors and Ca2+-pump ATPase have been shown to cause Ca2+-release and depress Ca2+ accumulation in the sarcoplasmic reticulum as a consequence of oxidative stress. Such alterations in sarcolemma and sarcoplasmic reticulum are considered to cause Ca2+-handling abnormalities, which are associated with mitochondrial Ca2+-overload and loss of myofibrillar Ca2+-sensitivity due to oxidative stress. Information regarding the direct effects of different oxyradicals and oxidants on subcellular organelles has also been outlined to show the mechanisms by which oxidative stress may induce Ca2+-handling abnormalities. These observations support the view that oxidative stress plays an important role in the genesis of subcellular defects and cardiac dysfunction in heart disease.
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Affiliation(s)
- Naranjan S. Dhalla
- St. Boniface Hospital Albrechtsen Research Centre, Institute of Cardiovascular Sciences, Department of Physiology and Pathophysiology, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB R2H 2A6, Canada;
- Correspondence: ; Tel.: +1-204-235-3417; Fax: +1-204-237-0347
| | - Vijayan Elimban
- St. Boniface Hospital Albrechtsen Research Centre, Institute of Cardiovascular Sciences, Department of Physiology and Pathophysiology, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB R2H 2A6, Canada;
| | - Monika Bartekova
- Centre of Experimental Medicine, Institute for Heart Research, Slovak Academy of Sciences, Dubravska cesta 9, 84104 Bratislava, Slovakia; (M.B.); (A.A.)
| | - Adriana Adameova
- Centre of Experimental Medicine, Institute for Heart Research, Slovak Academy of Sciences, Dubravska cesta 9, 84104 Bratislava, Slovakia; (M.B.); (A.A.)
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University Bratislava, Odbojarov 10, 83232 Bratislava, Slovakia
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3
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Bhullar S, Shah A, Dhalla N. Mechanisms for the development of heart failure and improvement of cardiac function by angiotensin-converting enzyme inhibitors. SCRIPTA MEDICA 2022. [DOI: 10.5937/scriptamed53-36256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Angiotensin-converting enzyme (ACE) inhibitors, which prevent the conversion of angiotensin I to angiotensin II, are well-known for the treatments of cardiovascular diseases, such as heart failure, hypertension and acute coronary syndrome. Several of these inhibitors including captopril, enalapril, ramipril, zofenopril and imidapril attenuate vasoconstriction, cardiac hypertrophy and adverse cardiac remodeling, improve clinical outcomes in patients with cardiac dysfunction and decrease mortality. Extensive experimental and clinical research over the past 35 years has revealed that the beneficial effects of ACE inhibitors in heart failure are associated with full or partial prevention of adverse cardiac remodeling. Since cardiac function is mainly determined by coordinated activities of different subcellular organelles, including sarcolemma, sarcoplasmic reticulum, mitochondria and myofibrils, for regulating the intracellular concentration of Ca2+ and myocardial metabolism, there is ample evidence to suggest that adverse cardiac remodelling and cardiac dysfunction in the failing heart are the consequence of subcellular defects. In fact, the improvement of cardiac function by different ACE inhibitors has been demonstrated to be related to the attenuation of abnormalities in subcellular organelles for Ca2+-handling, metabolic alterations, signal transduction defects and gene expression changes in failing cardiomyocytes. Various ACE inhibitors have also been shown to delay the progression of heart failure by reducing the formation of angiotensin II, the development of oxidative stress, the level of inflammatory cytokines and the occurrence of subcellular defects. These observations support the view that ACE inhibitors improve cardiac function in the failing heart by multiple mechanisms including the reduction of oxidative stress, myocardial inflammation and Ca2+-handling abnormalities in cardiomyocytes.
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4
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Bhullar SK, Shah AK, Dhalla NS. Role of angiotensin II in the development of subcellular remodeling
in heart failure. EXPLORATION OF MEDICINE 2021. [DOI: 10.37349/emed.2021.00054] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The development of heart failure under various pathological conditions such as myocardial infarction (MI), hypertension and diabetes are accompanied by adverse cardiac remodeling and cardiac dysfunction. Since heart function is mainly determined by coordinated activities of different subcellular organelles including sarcolemma, sarcoplasmic reticulum, mitochondria and myofibrils for regulating the intracellular concentration of Ca2+, it has been suggested that the occurrence of heart failure is a consequence of subcellular remodeling, metabolic alterations and Ca2+-handling abnormalities in cardiomyocytes. Because of the elevated plasma levels of angiotensin II (ANG II) due to activation of the renin-angiotensin system (RAS) in heart failure, we have evaluated the effectiveness of treatments with angiotensin converting enzyme (ACE) inhibitors and ANG II type 1 receptor (AT1R) antagonists in different experimental models of heart failure. Attenuation of marked alterations in subcellular activities, protein content and gene expression were associated with improvement in cardiac function in MI-induced heart failure by treatment with enalapril (an ACE inhibitor) or losartan (an AT1R antagonist). Similar beneficial effects of ANG II blockade on subcellular remodeling and cardiac performance were also observed in failing hearts due to pressure overload, volume overload or chronic diabetes. Treatments with enalapril and losartan were seen to reduce the degree of RAS activation as well as the level of oxidative stress in failing hearts. These observations provide evidence which further substantiate to support the view that activation of RAS and high level of plasma ANG II play a critical role in inducing subcellular defects and cardiac dys-function during the progression of heart failure.
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Affiliation(s)
- Sukhwinder K. Bhullar
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba R2H 2A6, Canada
| | - Anureet K. Shah
- School of Kinesiology, Nutrition and Food Science, California State University, Los Angeles, CA 90032, USA
| | - Naranjan S. Dhalla
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre, University of Manitoba, Winnipeg, Manitoba R2H 2A6, Canada; Department of Physiology and Pathophysiology, Max Rady College of Medicine, University of Manitoba, Winnipeg, Manitoba R3E 3P5, Canada
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5
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Non-Coding RNAs in the Cardiac Action Potential and Their Impact on Arrhythmogenic Cardiac Diseases. HEARTS 2021. [DOI: 10.3390/hearts2030026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Cardiac arrhythmias are prevalent among humans across all age ranges, affecting millions of people worldwide. While cardiac arrhythmias vary widely in their clinical presentation, they possess shared complex electrophysiologic properties at cellular level that have not been fully studied. Over the last decade, our current understanding of the functional roles of non-coding RNAs have progressively increased. microRNAs represent the most studied type of small ncRNAs and it has been demonstrated that miRNAs play essential roles in multiple biological contexts, including normal development and diseases. In this review, we provide a comprehensive analysis of the functional contribution of non-coding RNAs, primarily microRNAs, to the normal configuration of the cardiac action potential, as well as their association to distinct types of arrhythmogenic cardiac diseases.
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Oxidative Stress as A Mechanism for Functional Alterations in Cardiac Hypertrophy and Heart Failure. Antioxidants (Basel) 2021; 10:antiox10060931. [PMID: 34201261 PMCID: PMC8228897 DOI: 10.3390/antiox10060931] [Citation(s) in RCA: 74] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/01/2021] [Accepted: 06/06/2021] [Indexed: 12/23/2022] Open
Abstract
Although heart failure due to a wide variety of pathological stimuli including myocardial infarction, pressure overload and volume overload is associated with cardiac hypertrophy, the exact reasons for the transition of cardiac hypertrophy to heart failure are not well defined. Since circulating levels of several vasoactive hormones including catecholamines, angiotensin II, and endothelins are elevated under pathological conditions, it has been suggested that these vasoactive hormones may be involved in the development of both cardiac hypertrophy and heart failure. At initial stages of pathological stimuli, these hormones induce an increase in ventricular wall tension by acting through their respective receptor-mediated signal transduction systems and result in the development of cardiac hypertrophy. Some oxyradicals formed at initial stages are also involved in the redox-dependent activation of the hypertrophic process but these are rapidly removed by increased content of antioxidants in hypertrophied heart. In fact, cardiac hypertrophy is considered to be an adaptive process as it exhibits either normal or augmented cardiac function for maintaining cardiovascular homeostasis. However, exposure of a hypertrophied heart to elevated levels of circulating hormones due to pathological stimuli over a prolonged period results in cardiac dysfunction and development of heart failure involving a complex set of mechanisms. It has been demonstrated that different cardiovascular abnormalities such as functional hypoxia, metabolic derangements, uncoupling of mitochondrial electron transport, and inflammation produce oxidative stress in the hypertrophied failing hearts. In addition, oxidation of catecholamines by monoamine oxidase as well as NADPH oxidase activation by angiotensin II and endothelin promote the generation of oxidative stress during the prolonged period by these pathological stimuli. It is noteworthy that oxidative stress is known to activate metallomatrix proteases and degrade the extracellular matrix proteins for the induction of cardiac remodeling and heart dysfunction. Furthermore, oxidative stress has been shown to induce subcellular remodeling and Ca2+-handling abnormalities as well as loss of cardiomyocytes due to the development of apoptosis, necrosis, and fibrosis. These observations support the view that a low amount of oxyradical formation for a brief period may activate redox-sensitive mechanisms, which are associated with the development of cardiac hypertrophy. On the other hand, high levels of oxyradicals over a prolonged period may induce oxidative stress and cause Ca2+-handling defects as well as protease activation and thus play a critical role in the development of adverse cardiac remodeling and cardiac dysfunction as well as progression of heart failure.
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Mitochondrial Ca 2+ regulation in the etiology of heart failure: physiological and pathophysiological implications. Acta Pharmacol Sin 2020; 41:1301-1309. [PMID: 32694759 PMCID: PMC7608470 DOI: 10.1038/s41401-020-0476-5] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 07/04/2020] [Accepted: 07/06/2020] [Indexed: 12/14/2022] Open
Abstract
Heart failure (HF) represents one of the leading causes of cardiovascular diseases with high rates of hospitalization, morbidity and mortality worldwide. Ample evidence has consolidated a crucial role for mitochondrial injury in the progression of HF. It is well established that mitochondrial Ca2+ participates in the regulation of a wide variety of biological processes, including oxidative phosphorylation, ATP synthesis, reactive oxygen species (ROS) generation, mitochondrial dynamics and mitophagy. Nonetheless, mitochondrial Ca2+ overload stimulates mitochondrial permeability transition pore (mPTP) opening and mitochondrial swelling, resulting in mitochondrial injury, apoptosis, cardiac remodeling, and ultimately development of HF. Moreover, mitochondria possess a series of Ca2+ transport influx and efflux channels, to buffer Ca2+ in the cytoplasm. Interaction at mitochondria-associated endoplasmic reticulum membranes (MAMs) may also participate in the regulation of mitochondrial Ca2+ homeostasis and plays an essential role in the progression of HF. Here, we provide an overview of regulation of mitochondrial Ca2+ homeostasis in maintenance of cardiac function, in an effort to identify novel therapeutic strategies for the management of HF.
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Adameova A, Elimban V, Ganguly PK, Dhalla NS. β-1 adrenoceptors and AT1 receptors may not be involved in catecholamine-induced lethal arrhythmias. Can J Physiol Pharmacol 2019; 97:570-576. [DOI: 10.1139/cjpp-2018-0531] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An excessive amount of catecholamines produce arrhythmias, but the exact mechanisms of this action are not fully understood. For this purpose, Sprague–Dawley rats were treated with or without atenolol, a β1-adrenoceptor blocker (20 mg/kg per day), for 15 days followed by injections of epinephrine for cumulative doses of 4 to 128 μg/kg. Another group of animals were pretreated with losartan, an angiotensin receptor (AT1) blocker (20 mg/kg per day), for comparison. Control animals received saline. Varying degrees of ventricular arrhythmias were seen upon increasing the dose of epinephrine, but the incidence and duration of the rhythm abnormalities as well as the number of episodes and severity of arrhythmias were not affected by treating the animals with atenolol or losartan. The levels of both epinephrine and norepinephrine were increased in the atenolol-treated rats but were unchanged in the losartan-treated animals after the last injection of epinephrine; the severity of arrhythmias did not correlate with the circulating catecholamine levels. These results indicate that both β1-adrenoceptors and AT1 receptors may not be involved in the pathogenesis of catecholamine-induced arrhythmias and support the view that other mechanisms, such as the oxidation products of catecholamines, may play a crucial role in the occurrence of lethal arrhythmias.
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Affiliation(s)
- Adriana Adameova
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Comenius University 832 32 Bratislava, Odbojarov 10, Slovakia
| | - Vijayan Elimban
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre and Department of Physiology & Pathophysiology, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB R2H 2A6, Canada
| | - Paul K. Ganguly
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre and Department of Physiology & Pathophysiology, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB R2H 2A6, Canada
| | - Naranjan S. Dhalla
- Institute of Cardiovascular Sciences, St. Boniface Hospital Albrechtsen Research Centre and Department of Physiology & Pathophysiology, Max Rady College of Medicine, University of Manitoba, Winnipeg, MB R2H 2A6, Canada
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9
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Abstract
Angiotensin-converting enzyme (ACE) inhibitors improve the prognosis in mild, moderate and severe heart failure, as well as preventing the onset of heart failure in patients with chronic asymptomatic left-ventricular dysfunction and in those with reduced ejection fraction after myocardial infarction (MI). Imidapril is a long-acting ACE inhibitor that is rapidly converted in the liver to its active metabolite, imidaprilat. Maximum plasma concentrations of imidapril and imidaprilat are achieved after 2 and 5—6 hours, respectively, with corresponding elimination half-lives of 1.1—2.5 and 10—19 hours. Imidapril is used in the treatment of hypertension, chronic heart failure, acute MI and diabetic nephropathy. In patients with mild-tomoderate chronic heart failure, imidapril 10 mg once-daily increased exercise time and physical working capacity, decreased plasma atrial natriuretic peptide and brain natriuretic peptide levels and reduced blood pressure. It also improved left ventricular ejection fraction, being significantly more effective than bisoprolol, in patients with acute MI. Imidapril is well tolerated and preliminary studies suggest it has an advantage over captopril and enalapril in terms of a lower incidence of cough. In conclusion, imidapril is a well-investigated versatile ACE inhibitor for the treatment of a range ofACE inhibitor for the treatment of a range of cardiovascular diseases.
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Affiliation(s)
- Tomas Dolezal
- Department of Pharmacology, Charles University, Prague, Czech Republic.
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10
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Babick A, Chapman D, Zieroth S, Elimban V, Dhalla NS. Reversal of subcellular remodelling by losartan in heart failure due to myocardial infarction. J Cell Mol Med 2014; 16:2958-67. [PMID: 22947202 PMCID: PMC4393724 DOI: 10.1111/j.1582-4934.2012.01623.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2012] [Accepted: 08/28/2012] [Indexed: 11/27/2022] Open
Abstract
This study tested the reversal of subcellular remodelling in heart failure due to myocardial infarction (MI) upon treatment with losartan, an angiotensin II receptor antagonist. Twelve weeks after inducing MI, rats were treated with or without losartan (20 mg/kg; daily) for 8 weeks and assessed for cardiac function, cardiac remodelling, subcellular alterations and plasma catecholamines. Cardiac hypertrophy and lung congestion in 20 weeks MI-induced heart failure were associated with increases in plasma catecholamine levels. Haemodynamic examination revealed depressed cardiac function, whereas echocardiographic analysis showed impaired cardiac performance and marked increases in left ventricle wall thickness and chamber dilatation at 20 weeks of inducing MI. These changes in cardiac function, cardiac remodelling and plasma dopamine levels in heart failure were partially or fully reversed by losartan. Sarcoplasmic reticular (SR) Ca2+-pump activity and protein expression, protein and gene expression for phospholamban, as well as myofibrillar (MF) Ca2+-stimulated ATPase activity and α-myosin heavy chain mRNA levels were depressed, whereas β-myosin heavy chain expression was increased in failing hearts; these alterations were partially reversed by losartan. Although SR Ca2+-release activity and mRNA levels for SR Ca2+-pump were decreased in failing heart, these changes were not reversed upon losartan treatment; no changes in mRNA levels for SR Ca2+-release channels were observed in untreated or treated heart failure. These results suggest that the partial improvement of cardiac performance in heart failure due to MI by losartan treatment is associated with partial reversal of cardiac remodelling as well as partial recovery of SR and MF functions.
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Affiliation(s)
- Andrea Babick
- Department of Physiology, Institute of Cardiovascular Sciences, St Boniface Hospital Research, Winnipeg, Manitoba, Canada
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11
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Babick A, Elimban V, Zieroth S, Dhalla NS. Reversal of cardiac dysfunction and subcellular alterations by metoprolol in heart failure due to myocardial infarction. J Cell Physiol 2013; 228:2063-70. [DOI: 10.1002/jcp.24373] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 03/20/2013] [Indexed: 11/07/2022]
Affiliation(s)
- Andrea Babick
- Institute of Cardiovascular Sciences, St Boniface Hospital Research, Department of Physiology and Division of Cardiology, Faculty of Medicine; University of Manitoba; Winnipeg, Manitoba; Canada
| | - Vijayan Elimban
- Institute of Cardiovascular Sciences, St Boniface Hospital Research, Department of Physiology and Division of Cardiology, Faculty of Medicine; University of Manitoba; Winnipeg, Manitoba; Canada
| | - Shelley Zieroth
- Institute of Cardiovascular Sciences, St Boniface Hospital Research, Department of Physiology and Division of Cardiology, Faculty of Medicine; University of Manitoba; Winnipeg, Manitoba; Canada
| | - Naranjan S. Dhalla
- Institute of Cardiovascular Sciences, St Boniface Hospital Research, Department of Physiology and Division of Cardiology, Faculty of Medicine; University of Manitoba; Winnipeg, Manitoba; Canada
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Dhalla NS, Rangi S, Babick AP, Zieroth S, Elimban V. Cardiac remodeling and subcellular defects in heart failure due to myocardial infarction and aging. Heart Fail Rev 2013; 17:671-81. [PMID: 21850540 DOI: 10.1007/s10741-011-9278-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Although several risk factors including hypertension, cardiac hypertrophy, coronary artery disease, and diabetes are known to result in heart failure, elderly subjects are more susceptible to myocardial infarction and more likely to develop heart failure. This article is intended to discuss that cardiac dysfunction in hearts failing due to myocardial infarction and aging is associated with cardiac remodeling and defects in the subcellular organelles such as sarcolemma (SL), sarcoplasmic reticulum (SR), and myofibrils. Despite some differences in the pattern of heart failure due to myocardial infarction and aging with respect to their etiology and sequence of events, evidence has been presented to show that subcellular remodeling plays a critical role in the occurrence of intracellular Ca(2+)-overload and development of cardiac dysfunction in both types of failing heart. In particular, alterations in gene expression for SL and SR proteins induce Ca(2+)-handling abnormalities in cardiomyocytes, whereas those for myofibrillar proteins impair the interaction of Ca(2+) with myofibrils in hearts failing due to myocardial infarction and aging. In addition, different phosphorylation mechanisms, which regulate the activities of Ca(2+)-cycling proteins in SL and SR membranes as well as Ca(2+)-binding proteins in myofibrils, become defective in the failing heart. Accordingly, it is suggested that subcellular remodeling involving defects in Ca(2+)-handling and Ca(2+)-binding proteins as well as their regulatory mechanisms is intimately associated with cardiac remodeling and heart failure due to myocardial infarction and aging.
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Affiliation(s)
- Naranjan S Dhalla
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, 351 Tache Avenue, Winnipeg, MB, Canada.
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Abstract
It is believed that cardiac remodeling due to geometric and structural changes is a major mechanism for the progression of heart failure in different pathologies including hypertension, hypertrophic cardiomyopathy, dilated cardiomyopathy, diabetic cardiomyopathy, and myocardial infarction. Increases in the activities of proteolytic enzymes such as matrix metalloproteinases, calpains, cathepsins, and caspases contribute to the process of cardiac remodeling. In addition to modifying the extracellular matrix, both matrix metalloproteinases and cathepsins have been shown to affect the activities of subcellular organelles in cardiomyocytes. The activation of calpains and caspases has been identified to induce subcellular remodeling in failing hearts. Proteolytic activities associated with different proteins including caspases, calpain, and the ubiquitin-proteasome system have been shown to be involved in cardiomyocyte apoptosis, which is an integral part of cardiac remodeling. This article discusses and compares how the activities of various proteases are involved in different cardiac abnormalities with respect to alterations in apoptotic pathways, cardiac remodeling, and cardiac dysfunction. An imbalance appears to occur between the activities of some proteases and their endogenous inhibitors in various types of hypertrophied and failing hearts, and this is likely to further accentuate subcellular remodeling and cardiac dysfunction. The importance of inhibiting the activities of both extracellular and intracellular proteases specific to distinct etiologies, in attenuating cardiac remodeling and apoptosis as well as biochemical changes of subcellular organelles, in heart failure has been emphasized. It is suggested that combination therapy to inhibit different proteases may prove useful for the treatment of heart failure.
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Affiliation(s)
- Alison L Müller
- Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, Winnipeg, MB, Canada
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14
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Groban L, Lindsey S, Wang H, Lin MS, Kassik KA, Machado FSM, Carter CS. Differential effects of late-life initiation of low-dose enalapril and losartan on diastolic function in senescent Fischer 344 x Brown Norway male rats. AGE (DORDRECHT, NETHERLANDS) 2012; 34:831-43. [PMID: 21720770 PMCID: PMC3682061 DOI: 10.1007/s11357-011-9283-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Accepted: 06/14/2011] [Indexed: 05/14/2023]
Abstract
No proven pharmacological therapies to delay or reverse age-related diastolic dysfunction exist. We hypothesized that late-life low-dose (non-blood-pressure-lowering) angiotensin-converting enzyme inhibition vs. angiotensin II receptor blockade would be equally efficacious at mitigating diastolic dysfunction in the senescent Fischer 344 × Brown Norway rat. Enalapril (10 mg/kg/day; n = 9) initiated at 24 months of age and continued for 6 months, increased myocardial relaxation (e'), reduced Doppler-derived indices of filling pressure (E/e'), favorably lowered the ratio of phospholamban-SERCA2 and reduced oxidative stress markers, Rac1 and nitrotyrosine, in aged hearts. Treatment with losartan (15 mg/kg/day; n = 9) similarly mitigated signs of cardiac oxidative stress, but impairments in diastolic function persisted when compared with untreated rats (n = 7). Our findings favor the idea that the lusitropic benefit of low-dose angiotensin-converting enzyme inhibitor initiated late in life may be related to an antioxidant-mediated modulation of SERCA2, resulting in improved relaxation rather than via overt effects on cardiac structure or blood pressure.
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Affiliation(s)
- Leanne Groban
- />Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1009 USA
| | - Sarah Lindsey
- />Hypertension and Vascular Research Center, Wake Forest University School of Medicine, Winston-Salem, NC USA
| | - Hao Wang
- />Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1009 USA
| | - Marina S. Lin
- />Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1009 USA
| | - Kimberly A. Kassik
- />Department of Anesthesiology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157-1009 USA
| | - Frederico S. M. Machado
- />Institute of Biological Sciences, Department of Physiology and Biophysics, Federal University of Minas Gerais, Av. Antônio Carlos, 6627, 31270-901 Belo Horizonte, Minas Gerais Brazil
| | - Christy S. Carter
- />Department of Aging and Geriatric Research, Institute on Aging, College of Medicine, University of Florida, 210 E. Mowry Road, P.O. Box 112610, Gainesville, FL 32611 USA
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15
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Milberg P, Pott C, Frommeyer G, Fink M, Ruhe M, Matsuda T, Baba A, Klocke R, Quang TH, Nikol S, Stypmann J, Osada N, Müller FU, Breithardt G, Noble D, Eckardt L. Acute inhibition of the Na(+)/Ca(2+) exchanger reduces proarrhythmia in an experimental model of chronic heart failure. Heart Rhythm 2011; 9:570-8. [PMID: 22075452 DOI: 10.1016/j.hrthm.2011.11.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2011] [Indexed: 11/19/2022]
Abstract
BACKGROUND Molecular remodeling in heart failure includes slowing of repolarization, leading to proarrhythmia. OBJECTIVE To evaluate the effects of Na(+)/Ca(2+) exchanger (NCX) inhibition on repolarization as a novel antiarrhythmic concept in chronic heart failure (CHF). METHODS AND RESULTS CHF was induced by rapid ventricular pacing in rabbits. Left ventricular function was assessed by echocardiography. Monophasic action potentials (MAPs) showed a prolongation of repolarization in CHF after atrioventricular block and stimulation at different cycle lengths. Sotalol (100 μM, n = 13) or veratridine (0.5 μM; n = 15) resulted in a further significant increase in the MAP duration. CHF was associated with an increased dispersion of repolarization, as compared with sotalol-treated (+22 ± 7 ms; P < .05) and veratridine-treated (+20 ± 6 ms; P < .05) sham hearts. In the presence of a low potassium concentration, sotalol and veratridine reproducibly induced early afterdepolarizations (EADs) and polymorphic ventricular tachyarrhythmias (VTs). SEA0400 (1 μM), a pharmacological inhibitor of NCX, significantly shortened the MAP duration (P < .01) and reduced dispersion (P < .05). It suppressed EAD in 6 of 13 sotalol-treated failing hearts and in 9 of 10 veratridine-treated failing hearts, leading to a reduction in VT (60% in sotalol-treated failing hearts and 83% in veratridine-treated failing hearts). Simulations using a mathematical model showed a reduction in the action potential duration and the number of EADs by the NCX block in all subgroups. CONCLUSIONS In an experimental model of CHF, the acute inhibition of NCX (1) reduces the MAP duration, (2) decreases dispersion of repolarization, and (3) suppresses EAD and VT. Our observations indicate for the first time that pharmacological NCX inhibition increases repolarization reserve and protects against VTs in heart failure.
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Affiliation(s)
- Peter Milberg
- Division of Clinical and Experimental Electrophysiology, Department of Cardiology and Angiology, Westfälische Wilhelms-University, University Hospital Münster, Münster, Germany.
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Costa DG, da Silva JS, Kümmerle AE, Sudo RT, Landgraf SS, Caruso-Neves C, Fraga CA, de Lacerda Barreiro EJ, Zapata-Sudo G. LASSBio-294, A compound with inotropic and lusitropic activity, decreases cardiac remodeling and improves Ca²(+) influx into sarcoplasmic reticulum after myocardial infarction. Am J Hypertens 2010; 23:1220-7. [PMID: 20671720 DOI: 10.1038/ajh.2010.157] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Myocardial infarction (MI) is commonly associated with cardiac hypertrophy, reduced Ca²(+) uptake into the sarcoplasmic reticulum (SR) and impaired myocardial relaxation. Treatment to prevent MI-associated complications is currently lacking. The purpose of the present study was to investigate the remodeling and function of hearts subjected to experimental MI and to evaluate the response to treatment with a new thienylhydrazone: 3,4-methylenedioxybenzoyl-2-thienylhydrazone (LASSBio-294), which has demonstrated positive inotropic properties. METHODS LASSBio-294 (2 mg/kg) or vehicle (dimethyl sulfoxide) was administered daily by intraperitoneal injection for 4 weeks in sham-operated rats and rats with MI. Cardiac remodeling and hemodynamic parameters were monitored through histological and intraventricular pressure analyses. Intracellular Ca²(+) regulation (uptake and release) and the sensitivity of contractile proteins to Ca²(+) were evaluated by determining the contractile response of saponin-skinned cardiac cells from infarcted hearts. RESULTS Cardiac hypertrophy occurred at 4 weeks post-MI and was partially reverted by treatment with LASSBio-294. LASSBio-294 treatment also reduced the nuclear density, collagen volume fraction, and left ventricular end-diastolic pressure (LV EDP) induced by MI. MI led to reduced Ca²(+) uptake from the SR, but did not modify the Ca²(+) release or the Ca²(+)-force relationship. LASSBio-294 restored SR function and enhanced the sensitivity of contractile proteins to Ca²(+). CONCLUSION LASSBio-294 is a promising candidate for improving intracellular Ca²(+) regulation and preventing MI-induced cardiac dysfunction, which could potentially prevent heart failure (HF).
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Zhang W, Elimban V, Xu YJ, Zhang M, Nijjar MS, Dhalla NS. Alterations of cardiac ERK1/2 expression and activity due to volume overload were attenuated by the blockade of RAS. J Cardiovasc Pharmacol Ther 2010; 15:84-92. [PMID: 20100902 DOI: 10.1177/1074248409356430] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The activities and protein content of extracellular signal-regulated kinase (ERK)1/2 in the heart were measured in rats at 4 and 16 weeks after volume overload due to aortocaval shunt. Protein content of phosphorylated ERK1/2 was increased at both 4 and 16 weeks, whereas protein content of total ERK1/2 was increased only at 16 weeks of inducing volume overload. The ERK1/2 activities, estimated as phospho-Elk-1 content, were also increased at 4 and 16 weeks of inducing volume overload. The increased phosphorylated ERK1/2 and E-26-like (Elk)-1 protein content in 16 weeks failing hearts was much greater than that in 4 weeks hypertrophied hearts. These changes in phosphorylated ERK1/2 and Elk-1 protein content in both 4 and 16 weeks volume overloaded animals were attenuated by treatment with enalapril and/or losartan. The results indicate that activation of ERK1/2 may be involved in the development of cardiac hypertrophy and heart failure due to volume overload, and these changes are partially prevented by blockade of the renin-angiotensin system (RAS).
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Affiliation(s)
- Weihua Zhang
- Institute of Cardiovascular Sciences, St Boniface General Hospital Research Centre, Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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18
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Tappia PS, Sandhu H, Abbi T, Aroutiounova N. Alterations in the expression of myocardial calcium cycling genes in rats fed a low protein diet in utero. Mol Cell Biochem 2008; 324:93-9. [DOI: 10.1007/s11010-008-9988-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Accepted: 12/10/2008] [Indexed: 12/01/2022]
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Dhalla NS, Saini-Chohan HK, Rodriguez-Leyva D, Elimban V, Dent MR, Tappia PS. Subcellular remodelling may induce cardiac dysfunction in congestive heart failure. Cardiovasc Res 2008; 81:429-38. [DOI: 10.1093/cvr/cvn281] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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Cardiac contractility modulation electrical signals normalize activity, expression, and phosphorylation of the Na+-Ca2+ exchanger in heart failure. J Card Fail 2008; 15:48-56. [PMID: 19181294 DOI: 10.1016/j.cardfail.2008.08.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 08/18/2008] [Accepted: 08/29/2008] [Indexed: 11/20/2022]
Abstract
BACKGROUND Expression and phosphorylation of the cardiac Na(+)-Ca(2+) exchanger-1 (NCX-1) are up-regulated in heart failure (HF). We examined the effects of chronic cardiac contractility modulation (CCM) therapy on the expression and phosphorylation of NCX-1 and its regulators GATA-4 and FOG-2 in HF dogs. METHODS AND RESULTS Studies were performed in LV tissue from 7 CCM-treated HF dogs, 7 untreated HF dogs, and 6 normal (NL) dogs. mRNA expression of NCX-1, GATA-4, and FOG-2 was measured using reverse transcriptase polymerase chain reaction, and protein level was determined by Western blotting. Phosphorylated NCX-1 (P-NCX) was determined using a phosphoprotein enrichment kit. Compared with NL dogs, NCX-1 mRNA and protein expression and GATA-4 mRNA and protein expression increased in untreated HF dogs, whereas FOG-2 expression decreased. Compared with NL dogs, the level of P-NCX-1 normalized to total NCX-1 increased in untreated HF dogs (0.80+/-0.10 vs 0.37+/-0.04; P < .05). CCM therapy normalized NCX-1 expression, GATA-4, and FOG-2 expression, and the ratio of P-NCX-1 to total NCX-1 (0.62+/-0.10). CONCLUSION Chronic monotherapy with CCM restores expression and phosphorylation of NCX-1. These findings are consistent with previous observations of improved LV function and normalized sarcoplasmic reticulum calcium cycling in the left ventricles of HF dogs treated with CCM therapy.
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Guo X, Wang J, Elimban V, Dhalla NS. Both enalapril and losartan attenuate sarcolemmal Na+-K+-ATPase remodeling in failing rat heart due to myocardial infarctionThis article is one of a selection of papers published in the special issue Bridging the Gap: Where Progress in Cardiovascular and Neurophysiologic Research Meet. Can J Physiol Pharmacol 2008; 86:139-47. [DOI: 10.1139/y08-006] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate the mechanisms underlying the depressed sarcolemmal (SL) Na+-K+-ATPase activity in congestive heart failure (CHF), different isoforms and gene expression of Na+-K+-ATPase were examined in the failing left ventricle (LV) at 8 weeks after myocardial infarction (MI). In view of the increased activity of renin–angiotensin system (RAS) in CHF, these parameters were also studied after 5 weeks of treatment with enalapril (10 mg·kg–1·day–1), an angiotensin-converting enzyme inhibitor, and losartan (20 mg·kg–1·day–1), an angiotensin II type 1 receptor antagonist, starting at 3 weeks after the coronary ligation in rats. The infarcted animals showed LV dysfunction and depressed SL Na+-K+-ATPase activity. Protein content and mRNA levels for Na+-K+-ATPase α2isoform were decreased whereas those for Na+-K+-ATPase α3isoform were increased in the failing LV. On the other hand, no significant changes were observed in protein content or mRNA levels for Na+-K+-ATPase α1and β1isoforms. The treatment of infarcted animals with enalapril or losartan improved LV function and attenuated the depression in Na+-K+-ATPase α2isoform as well as the increase in α3isoform, at both the protein and mRNA levels; however, combination therapy with enalapril and losartan did not produce any additive effects. These results provide further evidence that CHF due to MI is associated with remodeling of SL membrane and suggest that the blockade of RAS plays an important role in preventing these alterations in the failing heart.
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Affiliation(s)
- Xiaobing Guo
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre and Department of Physiology, 351 Tache Ave, Faculty of Medicine, University of Manitoba, Winnipeg, MB R2H 2A6, Canada
| | - Jingwei Wang
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre and Department of Physiology, 351 Tache Ave, Faculty of Medicine, University of Manitoba, Winnipeg, MB R2H 2A6, Canada
| | - Vijayan Elimban
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre and Department of Physiology, 351 Tache Ave, Faculty of Medicine, University of Manitoba, Winnipeg, MB R2H 2A6, Canada
| | - Naranjan S. Dhalla
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre and Department of Physiology, 351 Tache Ave, Faculty of Medicine, University of Manitoba, Winnipeg, MB R2H 2A6, Canada
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O'Rourke B, Maack C. The role of Na dysregulation in cardiac disease and how it impacts electrophysiology. ACTA ACUST UNITED AC 2007; 4:207-217. [PMID: 18650959 DOI: 10.1016/j.ddmod.2007.11.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Ca(2+) is well known as the central player in cardiac cell physiology, mediating Ca(2+) activation of myosin ATPase and contraction, the stimulation of Ca(2+)-activated signaling pathways and modulation of mitochondrial energy production. Abnormalities of Ca(2+) handling are a well-studied mechanism of decompensation in heart failure. Less appreciated is the role of cytosolic Na(+) (Na(i) (+)), which can dramatically influence the transfer rates and distribution of Ca(2+) among the intracellular compartments of the myocyte. Since Na(i) (+) can vary widely under different physiological and pathological conditions, and its effects depend on multiple ion gradients and membrane electrical potentials, unraveling the global influence of Na(i) (+) on cell function is complex, requiring an integrative view of cardiomyocyte physiology. Here, we discuss how abnormal Na(i) (+) regulation not only influences the cytosolic Ca(2+) transient and the cellular action potential but also alters mitochondrial Ca(2+) uptake and the balance of energy supply and demand of the cardiomyocyte, which may contribute to oxidative stress and cardiac decompensation. The implications for sudden cardiac death and the potential for novel therapeutic interventions are discussed.
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Affiliation(s)
- Brian O'Rourke
- The Johns Hopkins University, Institute of Molecular Cardiobiology, Division of Cardiology, Baltimore, MD, USA
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Maack C, O'Rourke B. Excitation-contraction coupling and mitochondrial energetics. Basic Res Cardiol 2007; 102:369-92. [PMID: 17657400 PMCID: PMC2785083 DOI: 10.1007/s00395-007-0666-z] [Citation(s) in RCA: 188] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2007] [Revised: 06/12/2007] [Accepted: 06/13/2007] [Indexed: 12/20/2022]
Abstract
Cardiac excitation-contraction (EC) coupling consumes vast amounts of cellular energy, most of which is produced in mitochondria by oxidative phosphorylation. In order to adapt the constantly varying workload of the heart to energy supply, tight coupling mechanisms are essential to maintain cellular pools of ATP, phosphocreatine and NADH. To our current knowledge, the most important regulators of oxidative phosphorylation are ADP, Pi, and Ca2+. However, the kinetics of mitochondrial Ca2+-uptake during EC coupling are currently a matter of intense debate. Recent experimental findings suggest the existence of a mitochondrial Ca2+ microdomain in cardiac myocytes, justified by the close proximity of mitochondria to the sites of cellular Ca2+ release, i. e., the ryanodine receptors of the sarcoplasmic reticulum. Such a Ca2+ microdomain could explain seemingly controversial results on mitochondrial Ca2+ uptake kinetics in isolated mitochondria versus whole cardiac myocytes. Another important consideration is that rapid mitochondrial Ca2+ uptake facilitated by microdomains may shape cytosolic Ca2+ signals in cardiac myocytes and have an impact on energy supply and demand matching. Defects in EC coupling in chronic heart failure may adversely affect mitochondrial Ca2+ uptake and energetics, initiating a vicious cycle of contractile dysfunction and energy depletion. Future therapeutic approaches in the treatment of heart failure could be aimed at interrupting this vicious cycle.
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Affiliation(s)
- Christoph Maack
- Klinik für Innere Medizin III, Universitätsklinikum des Saarlandes, 66421, Homburg/Saar, Germany.
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Saini HK, Dhalla NS. Sarcolemmal cation channels and exchangers modify the increase in intracellular calcium in cardiomyocytes on inhibiting Na+-K+-ATPase. Am J Physiol Heart Circ Physiol 2007; 293:H169-81. [PMID: 17322410 DOI: 10.1152/ajpheart.00007.2007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Although inhibition of the sarcolemmal (SL) Na+-K+-ATPase is known to cause an increase in the intracellular concentration of Ca2+([Ca2+]i) by stimulating the SL Na+/Ca2+exchanger (NCX), the involvement of other SL sites in inducing this increase in [Ca2+]iis not fully understood. Isolated rat cardiomyocytes were treated with or without different agents that modify Ca2+movements by affecting various SL sites and were then exposed to ouabain. Ouabain was observed to increase the basal levels of both [Ca2+]iand intracellular Na+concentration ([Na+]i) as well as to augment the KCl-induced increases in both [Ca2+]iand [Na+]iin a concentration-dependent manner. The ouabain-induced changes in [Na+]iand [Ca2+]iwere attenuated by treatment with inhibitors of SL Na+/H+exchanger and SL Na+channels. Both the ouabain-induced increase in basal [Ca2+]iand augmentation of the KCl response were markedly decreased when cardiomyocytes were exposed to 0–10 mM Na+. Inhibitors of SL NCX depressed but decreasing extracellular Na+from 105–35 mM augmented the ouabain-induced increase in basal [Ca2+]iand the KCl response. Not only was the increase in [Ca2+]iby ouabain dependent on the extracellular Ca2+concentration, but it was also attenuated by inhibitors of SL L-type Ca2+channels and store-operated Ca2+channels (SOC). Unlike the SL L-type Ca2+-channel blocker, the blockers of SL Na+channel and SL SOC, when used in combination with SL NCX inhibitor, showed additive effects in reducing the ouabain-induced increase in basal [Ca2+]i. These results support the view that in addition to SL NCX, SL L-type Ca2+channels and SL SOC may be involved in raising [Ca2+]ion inhibition of the SL Na+-K+-ATPase by ouabain. Furthermore, both SL Na+/H+exchanger and Na+channels play a critical role in the ouabain-induced Ca2+increase in cardiomyocytes.
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Affiliation(s)
- Harjot K Saini
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, 351 Tache Avenue, Winnipeg, Manitoba, Canada
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25
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Liu X, Suzuki H, Sethi R, Tappia PS, Takeda N, Dhalla NS. Blockade of the renin-angiotensin system attenuates sarcolemma and sarcoplasmic reticulum remodeling in chronic diabetes. Ann N Y Acad Sci 2007; 1084:141-54. [PMID: 17151298 DOI: 10.1196/annals.1372.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Although the defects in the sarcolemma (SL) and sarcoplasmic reticulum (SR) membranes are known to be associated with cardiac dysfunction in chronic diabetes, very little information regarding the mechanisms of these membrane abnormalities is available in the literature. For this reason, rats were treated daily for 8 weeks with and without enalapril, an angiotensin-converting enzyme inhibitor, or losartan, an angiotensin receptor antagonist, 3 days after inducing diabetes with an injection of streptozocin. Treatment of diabetic animals with both enalapril and losartan attenuated alterations in cardiac function and the left ventricular redox potential without any changes in the increased plasma glucose or reduced plasma insulin levels. The SL Na+-K+ ATPase, Ca2+ pump, Na+-dependent Ca2+-uptake, Ca2+-channel density, and low-affinity Ca2+-binding activities were depressed whereas Ca2+ ecto-ATPase activity was increased in the diabetic heart. Furthermore, the SR Ca2+-release and Ca2+-pump activities in the diabetic hearts were decreased without any changes in the Mg2+-ATPase activity. These alterations in SL and SR membranes in diabetic animals were partly prevented by treatments with enalapril and losartan. The results suggest that the activation of the renin-angiotensin system plays an important role in diabetes-induced changes in SL and SR membranes as well as cardiac function.
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Affiliation(s)
- Xueliang Liu
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, 351 Tache Avenue, Winnipeg, Manitoba, Canada R2H 2A6
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Tappia PS, Dent MR, Aroutiounova N, Babick AP, Weiler H. Gender differences in the modulation of cardiac gene expression by dietary conjugated linoleic acid isomersThis paper is one of a selection of papers published in this Special Issue, entitled The Cellular and Molecular Basis of Cardiovascular Dysfunction, Dhalla 70th Birthday Tribute. Can J Physiol Pharmacol 2007; 85:465-75. [PMID: 17612656 DOI: 10.1139/y06-104] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In an earlier study, we showed that dietary conjugated linoleic acid (CLA) isomers can exert differential effects on heart function in male and female rats, but the underlying mechanisms for these actions are not known. Cardiomyocyte Ca2+ cycling is a key event in normal cardiac contractile function and defects in Ca2+ cycling are associated with cardiac dysfunction and heart disease. We therefore hypothesized that abnormalities in the sarcolemmal (SL) and sarcoplasmic reticulum (SR)-mediated regulation of intracellular Ca2+ contribute to altered cardiac contractile function of male and female rats owing to dietary CLA isomers. Healthy male and female Sprague–Dawley rats were fed different CLA isomers, (cis-9, trans-11 (c9,t11) and trans-10, cis-12 (t10,c12)) individually and in combination (50:50 mix as triglyceride or fatty acids) from 4 to 20 weeks of age. We determined the mRNA levels of sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) 2a, ryanodine receptor, phospholamban, calsequestrin, Na+–Ca2+-exchanger (NCX), and L-type Ca2+ channel in the left ventricle (LV) by RT-PCR. The SR function was assessed by measurement of Ca2+-uptake and -release. Significant gender differences were seen in the LV NCX, L-type Ca2+ channel, and ryanodine receptor mRNA expression levels in control male and female rats. Dietary CLA isomers in the various forms induced changes in the mRNA levels of SERCA 2a, NCX, and L-type Ca2+ channel in the LV of both male and female hearts. Whereas protein contents of the Ca2+ cycling proteins were altered, changes in SR Ca2+-uptake and -release were also detected in both male and female rats in response to dietary CLA. The results of this study demonstrate that long-term dietary supplementation can modulate cardiac gene expression and SR function in a gender-related manner and may, in part, contribute to altered cardiac contractility.
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Affiliation(s)
- Paramjit S Tappia
- Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre and Department of Human Nutritional Sciences, Faculties of Human Ecology and Medicine, University of Manitoba, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada.
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27
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Babick AP, Dhalla NS. Role of subcellular remodeling in cardiac dysfunction due to congestive heart failure. Med Princ Pract 2007; 16:81-9. [PMID: 17303941 DOI: 10.1159/000098358] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2005] [Accepted: 07/06/2006] [Indexed: 11/19/2022] Open
Abstract
Although alterations in the size and shape of the heart (cardiac remodeling) are considered in explaining cardiac dysfunction during the development of congestive heart failure (CHF), there are several conditions including initial stages of cardiac hypertrophy, where cardiac remodeling has also been found to be associated with either an increased or no change in heart function. Extensive studies have indicated that cardiac dysfunction is related to defects in one or more subcellular organelles such as myofibrils, sarcoplasmic reticulum and sarcolemma, depending upon the stage of CHF. Such subcellular abnormalities in the failing hearts have been shown to occur at both genetic and protein levels. Blockade of the renin-angiotensin system has been reported to partially attenuate changes in subcellular protein, gene expression, functional activities and cardiac performance in CHF. These observations provide support for the role of subcellular remodeling (alterations in molecular and biochemical composition of subcellular organelles) in cardiac dysfunction in the failing heart. On the basis of existing knowledge, it appears that subcellular remodeling during the process of cardiac remodeling plays a major role in the development of cardiac dysfunction in CHF.
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Affiliation(s)
- Andrea P Babick
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Center and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada
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Chakraborti S, Das S, Kar P, Ghosh B, Samanta K, Kolley S, Ghosh S, Roy S, Chakraborti T. Calcium signaling phenomena in heart diseases: a perspective. Mol Cell Biochem 2006; 298:1-40. [PMID: 17119849 DOI: 10.1007/s11010-006-9355-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2006] [Accepted: 10/12/2006] [Indexed: 01/24/2023]
Abstract
Ca(2+) is a major intracellular messenger and nature has evolved multiple mechanisms to regulate free intracellular (Ca(2+))(i) level in situ. The Ca(2+) signal inducing contraction in cardiac muscle originates from two sources. Ca(2+) enters the cell through voltage dependent Ca(2+) channels. This Ca(2+) binds to and activates Ca(2+) release channels (ryanodine receptors) of the sarcoplasmic reticulum (SR) through a Ca(2+) induced Ca(2+) release (CICR) process. Entry of Ca(2+) with each contraction requires an equal amount of Ca(2+) extrusion within a single heartbeat to maintain Ca(2+) homeostasis and to ensure relaxation. Cardiac Ca(2+) extrusion mechanisms are mainly contributed by Na(+)/Ca(2+) exchanger and ATP dependent Ca(2+) pump (Ca(2+)-ATPase). These transport systems are important determinants of (Ca(2+))(i) level and cardiac contractility. Altered intracellular Ca(2+) handling importantly contributes to impaired contractility in heart failure. Chronic hyperactivity of the beta-adrenergic signaling pathway results in PKA-hyperphosphorylation of the cardiac RyR/intracellular Ca(2+) release channels. Numerous signaling molecules have been implicated in the development of hypertrophy and failure, including the beta-adrenergic receptor, protein kinase C, Gq, and the down stream effectors such as mitogen activated protein kinases pathways, and the Ca(2+) regulated phosphatase calcineurin. A number of signaling pathways have now been identified that may be key regulators of changes in myocardial structure and function in response to mutations in structural components of the cardiomyocytes. Myocardial structure and signal transduction are now merging into a common field of research that will lead to a more complete understanding of the molecular mechanisms that underlie heart diseases. Recent progress in molecular cardiology makes it possible to envision a new therapeutic approach to heart failure (HF), targeting key molecules involved in intracellular Ca(2+) handling such as RyR, SERCA2a, and PLN. Controlling these molecular functions by different agents have been found to be beneficial in some experimental conditions.
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Affiliation(s)
- Sajal Chakraborti
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani, 741235, West Bengal, India.
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Sethi R, Saini HK, Wang X, Elimban V, Babick A, Dhalla NS. Differential changes in β-adrenoceptor signal transduction in left and right ventricles of infarcted ratsThis paper is one of a selection of papers published in this Special issue, entitled Second Messengers and Phosphoproteins—12th International Conference. Can J Physiol Pharmacol 2006; 84:747-54. [PMID: 16998538 DOI: 10.1139/y05-150] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although different experimental and clinical studies have revealed varying degrees of defects in β-adrenoceptors (β-ARs) during the development of heart failure, the mechanisms for differences in β-AR signal transduction between the left (LV) and right ventricle (RV) are not understood. Because biochemical alterations in the myocardium depend on the stage of heart disease, this study was undertaken to assess the status of β-ARs in the LV and RV at different stages of heart failure. Myocardial infarction was induced in rats by occluding the left coronary artery for 8 and 24 weeks. The β-AR signal transduction was monitored by measuring β1-AR density, the isoproterenol-induced positive inotropic effect, the increase in [Ca2+]i in cardiomyocytes, and the activation of adenylyl cyclase. The β-AR signal transduction parameters in the 8- and 24-week failing LV were depressed, whereas the RV showed upregulation at 8 weeks and downregulation at 24 weeks of these mechanisms. These results suggest that β-AR-mediated signal transduction in the LV and RV are differentially regulated and are dependent upon the stage of development of congestive heart failure due to myocardial infarction.
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Affiliation(s)
- Rajat Sethi
- Irma Lerma Rangel College of Pharmacy, Department of Pharmaceutical Sciences, TX A&M University, TX, USA
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Dhalla NS, Dent MR, Tappia PS, Sethi R, Barta J, Goyal RK. Subcellular remodeling as a viable target for the treatment of congestive heart failure. J Cardiovasc Pharmacol Ther 2006; 11:31-45. [PMID: 16703218 DOI: 10.1177/107424840601100103] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
It is now well known that congestive heart failure (CHF) is invariably associated with cardiac hypertrophy, and changes in the shape and size of cardiomyocytes (cardiac remodeling) are considered to explain cardiac dysfunction in CHF. However, the mechanisms responsible for the transition of cardiac hypertrophy to heart failure are poorly understood. Several lines of evidence both from various experimental models of CHF and from patients with different types of CHF have indicated that the functions of different subcellular organelles such as extracellular matrix, sarcolemma, sarcoplasmic reticulum, myofibrils, mitochondria, and nucleus are defective. Subcellular abnormalities for protein contents, gene expression, and enzyme activities in the failing heart become evident as a consequence of prolonged hormonal imbalance, metabolic derangements, and cation maldistribution. In particular, the occurrence of oxidative stress, development of intracellular Ca2+ overload, activation of proteases and phospholipases, and alterations in cardiac gene expression result in changes in the biochemical composition, molecular structure, and function of different subcellular organelles (subcellular remodeling). Not only does subcellular remodeling appear to be intimately involved in the transition of cardiac hypertrophy to heart failure, the mismatching of the function of different subcellular organelles leads to the development of cardiac dysfunction. Although blockade of the renin-angiotensin system, sympathetic nervous system, and various other hormonal actions have been reported to produce beneficial effects on cardiac remodeling and heart dysfunction in CHF, the actions of various cardiac drugs on subcellular remodeling have not been examined extensively. Some recent studies have indicated that both the angiotensin-converting enzyme inhibitors and angiotensin receptor antagonists attenuate changes in sarcolemma, sarcoplasmic reticulum, and myofibril enzyme activities, protein contents, and gene expression, and partly improve cardiac function in the failing hearts. It is suggested that subcellular remodeling is an excellent target for the development of improved drug therapy for CHF. Furthermore, extensive studies should investigate the effects of different agents individually or in combination on reverse subcellular remodeling, cardiac remodeling, and cardiac dysfunction in various experimental models of CHF.
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Affiliation(s)
- Naranjan S Dhalla
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, and Department of Physiology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
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31
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Dent MR, Aroutiounova N, Dhalla NS, Tappia PS. Losartan attenuates phospholipase C isozyme gene expression in hypertrophied hearts due to volume overload. J Cell Mol Med 2006; 10:470-9. [PMID: 16796812 PMCID: PMC3933134 DOI: 10.1111/j.1582-4934.2006.tb00412.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2006] [Accepted: 05/16/2006] [Indexed: 11/29/2022] Open
Abstract
Because the left ventricular (LV) hypertrophy due to volume overload induced by arteriovenous (AV) shunt was associated with an increase in phospholipase C (PLC) isozyme mRNA levels, PLC is considered to be involved in the development of cardiac hypertrophy. Since the renin-angiotensin system (RAS) is activated in cardiac hypertrophy, the role of RAS in the stimulation of PLC isozyme gene expression in hypertrophied heart was investigated by inducing AV shunt in Sprague-Dawley rats. The animals were treated with or without losartan (20 mg/kg, daily) for 3 days as well as 1, 2 and 4 weeks, and atria, right ventricle (RV) and LV were used for analysis. The increased muscle mass as well as the mRNA levels for PLC beta1 and beta3 in atria and RV, unlike PLC beta3 gene expression in LV, at 3 days of AVshunt were attenuated by losartan. The increased gene expression for PLC beta1 at 2 weeks in atria, at 1 and 4 weeks in RV, and at 2 and 4 weeks in LV was also depressed by losartan treatment. Likewise, the elevated mRNA levels for PLC beta3 in RV at 1 week and in LVat 4 weeks of cardiac hypertrophy were decreased by losartan. On the other hand, the increased levels of mRNA for PLC gamma1 in RV and LV at 2 and 4 weeks of inducing hypertrophy, unlike in atria at 4 weeks were not attenuated by losartan treatment. While the increased mRNA level for PLC delta1 in LV was reduced by losartan, gene expression for PLC delta1 was unaltered in atria and decreased in RV at 3 days of inducing AV shunt. These results suggest that changes in PLC isozyme gene expression were chamber specific and time-dependent upon inducing cardiac hypertrophy due to AV shunt. Furthermore, partial attenuation of the increased gene expression for some of the PLC isozymes and no effect of losartan on others indicate that both RAS dependent and independent mechanisms may be involved in hypertrophied hearts due to volume overload.
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Affiliation(s)
- Melissa R Dent
- Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, Canada Department of Physiology, Faculty of Medicine, University of Manitoba WinnipegCanada
| | - Nina Aroutiounova
- Department of Human Nutritional Sciences, Faculty of Human Ecology, University of ManitobaWinnipeg, Canada
| | - N S Dhalla
- Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, Canada Department of Physiology, Faculty of Medicine, University of Manitoba WinnipegCanada
| | - P S Tappia
- Department of Human Nutritional Sciences, Faculty of Human Ecology, University of ManitobaWinnipeg, Canada
- Department of Human Anatomy and Cell Science, Faculty of Medicine, University of ManitobaWinnipeg, Canada
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32
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Zhang XQ, Moorman JR, Ahlers BA, Carl LL, Lake DE, Song J, Mounsey JP, Tucker AL, Chan YM, Rothblum LI, Stahl RC, Carey DJ, Cheung JY. Phospholemman overexpression inhibits Na+-K+-ATPase in adult rat cardiac myocytes: relevance to decreased Na+ pump activity in postinfarction myocytes. J Appl Physiol (1985) 2005; 100:212-20. [PMID: 16195392 PMCID: PMC1351072 DOI: 10.1152/japplphysiol.00757.2005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Messenger RNA levels of phospholemman (PLM), a member of the FXYD family of small single-span membrane proteins with putative ion-transport regulatory properties, were increased in postmyocardial infarction (MI) rat myocytes. We tested the hypothesis that the previously observed reduction in Na+-K+-ATPase activity in MI rat myocytes was due to PLM overexpression. In rat hearts harvested 3 and 7 days post-MI, PLM protein expression was increased by two- and fourfold, respectively. To simulate increased PLM expression post-MI, PLM was overexpressed in normal adult rat myocytes by adenovirus-mediated gene transfer. PLM overexpression did not affect the relative level of phosphorylation on serine68 of PLM. Na+-K+-ATPase activity was measured as ouabain-sensitive Na+-K+ pump current (Ip). Compared with control myocytes overexpressing green fluorescent protein alone, Ip measured in myocytes overexpressing PLM was significantly (P < 0.0001) lower at similar membrane voltages, pipette Na+ ([Na+]pip) and extracellular K+ ([K+]o) concentrations. From -70 to +60 mV, neither [Na+]pip nor [K+]o required to attain half-maximal Ip was significantly different between control and PLM myocytes. This phenotype of decreased V(max) without appreciable changes in K(m) for Na+ and K+ in PLM-overexpressed myocytes was similar to that observed in MI rat myocytes. Inhibition of Ip by PLM overexpression was not due to decreased Na+-K+-ATPase expression because there were no changes in either protein or messenger RNA levels of either alpha1- or alpha2-isoforms of Na+-K+-ATPase. In native rat cardiac myocytes, PLM coimmunoprecipitated with alpha-subunits of Na+-K+-ATPase. Inhibition of Na+-K+-ATPase by PLM overexpression, in addition to previously reported decrease in Na+-K+-ATPase expression, may explain altered V(max) but not K(m) of Na+-K+-ATPase in postinfarction rat myocytes.
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Affiliation(s)
- Xue-Qian Zhang
- Department of Cellular and Molecular Physiology and
- Weis Center for Research, Geisinger Medical Center, Danville, PA 17822; and
| | - J. Randall Moorman
- Department of Internal Medicine (Cardiovascular Division), University of Virginia Health Sciences Center, Charlottesville, VA 22908
| | - Belinda A. Ahlers
- Department of Cellular and Molecular Physiology and
- Weis Center for Research, Geisinger Medical Center, Danville, PA 17822; and
| | - Lois L. Carl
- Department of Cellular and Molecular Physiology and
- Weis Center for Research, Geisinger Medical Center, Danville, PA 17822; and
| | - Douglas E. Lake
- Department of Internal Medicine (Cardiovascular Division), University of Virginia Health Sciences Center, Charlottesville, VA 22908
| | - Jianliang Song
- Department of Cellular and Molecular Physiology and
- Weis Center for Research, Geisinger Medical Center, Danville, PA 17822; and
| | - J. Paul Mounsey
- Department of Internal Medicine (Cardiovascular Division), University of Virginia Health Sciences Center, Charlottesville, VA 22908
| | - Amy L. Tucker
- Department of Internal Medicine (Cardiovascular Division), University of Virginia Health Sciences Center, Charlottesville, VA 22908
| | - Yiu-mo Chan
- Weis Center for Research, Geisinger Medical Center, Danville, PA 17822; and
| | | | - Richard C. Stahl
- Weis Center for Research, Geisinger Medical Center, Danville, PA 17822; and
| | - David J. Carey
- Weis Center for Research, Geisinger Medical Center, Danville, PA 17822; and
| | - Joseph Y. Cheung
- Department of Cellular and Molecular Physiology and
- Department of Medicine, Milton S. Hershey Medical Center, Pennsylvania State University, PA 17033
- Weis Center for Research, Geisinger Medical Center, Danville, PA 17822; and
- Address Correspondence To: Joseph Y. Cheung, M.D., Ph.D., Department of Cellular and Molecular Physiology, Milton S. Hershey Medical Center MC-H166, Hershey, PA 17033, Tel. 717-531-5748, Fax. 717-531-7667,
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