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Divya KP, Kanwar N, Anuranjana PV, Kumar G, Beegum F, George KT, Kumar N, Nandakumar K, Kanwal A. SIRT6 in Regulation of Mitochondrial Damage and Associated Cardiac Dysfunctions: A Possible Therapeutic Target for CVDs. Cardiovasc Toxicol 2024; 24:598-621. [PMID: 38689163 DOI: 10.1007/s12012-024-09858-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 04/05/2024] [Indexed: 05/02/2024]
Abstract
Cardiovascular diseases (CVDs) can be described as a global health emergency imploring possible prevention strategies. Although the pathogenesis of CVDs has been extensively studied, the role of mitochondrial dysfunction in CVD development has yet to be investigated. Diabetic cardiomyopathy, ischemic-reperfusion injury, and heart failure are some of the CVDs resulting from mitochondrial dysfunction Recent evidence from the research states that any dysfunction of mitochondria has an impact on metabolic alteration, eventually causes the death of a healthy cell and therefore, progressively directing to the predisposition of disease. Cardiovascular research investigating the targets that both protect and treat mitochondrial damage will help reduce the risk and increase the quality of life of patients suffering from various CVDs. One such target, i.e., nuclear sirtuin SIRT6 is strongly associated with cardiac function. However, the link between mitochondrial dysfunction and SIRT6 concerning cardiovascular pathologies remains poorly understood. Although the Role of SIRT6 in skeletal muscles and cardiomyocytes through mitochondrial regulation has been well understood, its specific role in mitochondrial maintenance in cardiomyocytes is poorly determined. The review aims to explore the domain-specific function of SIRT6 in cardiomyocytes and is an effort to know how SIRT6, mitochondria, and CVDs are related.
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Affiliation(s)
- K P Divya
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, 576104, India
| | - Navjot Kanwar
- Department of Pharmaceutical Sciences and Technology, Maharaja Ranjit Singh Punjab, Technical University, Bathinda, Punjab, 151005, India
| | - P V Anuranjana
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, 576104, India
| | - Gautam Kumar
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, 576104, India
- School of Pharmacy, Sharda University, Greater Noida, Uttar Pradesh, 201310, India
| | - Fathima Beegum
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, 576104, India
| | - Krupa Thankam George
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, 576104, India
| | - Nitesh Kumar
- Department of Pharmacology, National Institute of Pharmaceutical Educations and Research, Hajipur, Bihar, 844102, India
| | - K Nandakumar
- Department of Pharmacology, Manipal College of Pharmaceutical Sciences, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka, 576104, India.
| | - Abhinav Kanwal
- Department of Pharmacology, All India Institute of Medical Sciences, Bathinda, Punjab, 151005, India.
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2
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Su W, van Wijk SW, Brundel BJJM. Desmin variants: Trigger for cardiac arrhythmias? Front Cell Dev Biol 2022; 10:986718. [PMID: 36158202 PMCID: PMC9500482 DOI: 10.3389/fcell.2022.986718] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 08/22/2022] [Indexed: 11/30/2022] Open
Abstract
Desmin (DES) is a classical type III intermediate filament protein encoded by the DES gene. Desmin is abundantly expressed in cardiac, skeletal, and smooth muscle cells. In these cells, desmin interconnects several protein-protein complexes that cover cell-cell contact, intracellular organelles such as mitochondria and the nucleus, and the cytoskeletal network. The extra- and intracellular localization of the desmin network reveals its crucial role in maintaining the structural and mechanical integrity of cells. In the heart, desmin is present in specific structures of the cardiac conduction system including the sinoatrial node, atrioventricular node, and His-Purkinje system. Genetic variations and loss of desmin drive a variety of conditions, so-called desminopathies, which include desmin-related cardiomyopathy, conduction system-related atrial and ventricular arrhythmias, and sudden cardiac death. The severe cardiac disease outcomes emphasize the clinical need to understand the molecular and cellular role of desmin driving desminopathies. As the role of desmin in cardiomyopathies has been discussed thoroughly, the current review is focused on the role of desmin impairment as a trigger for cardiac arrhythmias. Here, the molecular and cellular mechanisms of desmin to underlie a healthy cardiac conduction system and how impaired desmin triggers cardiac arrhythmias, including atrial fibrillation, are discussed. Furthermore, an overview of available (genetic) desmin model systems for experimental cardiac arrhythmia studies is provided. Finally, potential implications for future clinical treatments of cardiac arrhythmias directed at desmin are highlighted.
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Affiliation(s)
- Wei Su
- Physiology, Amsterdam UMC Location Vrije Universiteit Amsterdam, Amsterdam, Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure and Arrhythmias, Amsterdam UMC Location Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Stan W. van Wijk
- Physiology, Amsterdam UMC Location Vrije Universiteit Amsterdam, Amsterdam, Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure and Arrhythmias, Amsterdam UMC Location Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Bianca J. J. M. Brundel
- Physiology, Amsterdam UMC Location Vrije Universiteit Amsterdam, Amsterdam, Netherlands
- Amsterdam Cardiovascular Sciences, Heart Failure and Arrhythmias, Amsterdam UMC Location Vrije Universiteit Amsterdam, Amsterdam, Netherlands
- *Correspondence: Bianca J. J. M. Brundel,
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3
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Wang Y, Li P, Zhang X, Li L, Liu M, Li X, Dai Y, Zhang C, Li S. Mitochondrial-Respiration-Improving Effects of Three Different Gardeniae Fructus Preparations and Their Components. ACS OMEGA 2021; 6:34229-34241. [PMID: 34963909 PMCID: PMC8697009 DOI: 10.1021/acsomega.1c03265] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 11/25/2021] [Indexed: 05/24/2023]
Abstract
The processing method for Chinese traditional herbal medicine is "Pao Zhi" in Chinese. This study examined the efficacy of the Pao Zhi on the preparations of Gardeniae Fructus (GF) on a mitochondrial respiratory function in rats. To determine the efficacy of Pao Zhi, we investigated the effects of GF heat processing on mitochondrial respiratory function. To test the GF components, the rats were randomly divided into a geniposide-alone group, crocin-alone group, and combination groups and treated with geniposide and crocin at different ratios. The results showed that a high dose, raw GF was more effective in improving the neurological function, mitochondrial respiratory function, and activities of Na+-K+-ATPase and Ca2+-Mg2+-ATPase than the preparations that underwent heating. Moreover, mitochondrial ROS production was the lowest in the raw GF-treated group. In addition, treatments with crocin and GC3 were more effective than geniposide in improving the functional deficit in MCAO rats. In conclusion, our results suggest that raw GF is the most suitable preparation for the treatment of cerebral ischemia, and its underlying mechanisms may be associated with the improvement of mitochondrial respiratory function, increased activities of Na+-K+-ATPase and Ca2+-Mg2+-ATPase, and reduced oxidative stress in mitochondria. Our findings suggest that raw GF, especially crocin, could be an ideal therapeutic agent for ischemic stroke.
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Affiliation(s)
- Yun Wang
- Institute
of Chinese Materia Medica, China Academy
of Chinese Medical Sciences, Beijing 100700, China
| | - Puling Li
- Institute
of Chinese Materia Medica, China Academy
of Chinese Medical Sciences, Beijing 100700, China
- School
of Pharmacy, Henan University of TCM, Zhengzhou 450008, China
| | - Xue Zhang
- Institute
of Chinese Materia Medica, China Academy
of Chinese Medical Sciences, Beijing 100700, China
| | - Lingyun Li
- Institute
of Chinese Materia Medica, China Academy
of Chinese Medical Sciences, Beijing 100700, China
- School
of Pharmacy, Henan University of TCM, Zhengzhou 450008, China
| | - Mengjiao Liu
- Institute
of Chinese Materia Medica, China Academy
of Chinese Medical Sciences, Beijing 100700, China
| | - Xiaoqing Li
- Institute
of Chinese Materia Medica, China Academy
of Chinese Medical Sciences, Beijing 100700, China
- School
of Pharmacy, Henan University of TCM, Zhengzhou 450008, China
| | - Yejia Dai
- Institute
of Chinese Materia Medica, China Academy
of Chinese Medical Sciences, Beijing 100700, China
| | - Cun Zhang
- Institute
of Chinese Materia Medica, China Academy
of Chinese Medical Sciences, Beijing 100700, China
- School
of Pharmacy, Henan University of TCM, Zhengzhou 450008, China
| | - Shaojing Li
- Institute
of Chinese Materia Medica, China Academy
of Chinese Medical Sciences, Beijing 100700, China
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4
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Abstract
Mitochondria have been recognized as key organelles in cardiac physiology and are potential targets for clinical interventions to improve cardiac function. Mitochondrial dysfunction has been accepted as a major contributor to the development of heart failure. The main function of mitochondria is to meet the high energy demands of the heart by oxidative metabolism. Ionic homeostasis in mitochondria directly regulates oxidative metabolism, and any disruption in ionic homeostasis causes mitochondrial dysfunction and eventually contractile failure. The mitochondrial ionic homeostasis is closely coupled with inner mitochondrial membrane potential. To regulate and maintain ionic homeostasis, mitochondrial membranes are equipped with ion transporting proteins. Ion transport mechanisms involving several different ion channels and transporters are highly efficient and dynamic, thus helping to maintain the ionic homeostasis of ions as well as their salts present in the mitochondrial matrix. In recent years, several novel proteins have been identified on the mitochondrial membranes and these proteins are actively being pursued in research for roles in the organ as well as organelle physiology. In this article, the role of mitochondrial ion channels in cardiac function is reviewed. In recent times, the major focus of the mitochondrial ion channel field is to establish molecular identities as well as assigning specific functions to them. Given the diversity of mitochondrial ion channels and their unique roles in cardiac function, they present novel and viable therapeutic targets for cardiac diseases.
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Affiliation(s)
- Harpreet Singh
- Department of Physiology and Cell Biology, The Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University College of Medicine, Columbus, Ohio
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5
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Cardiac hybrid imaging: novel tracers for novel targets. JOURNAL OF GERIATRIC CARDIOLOGY : JGC 2021; 18:748-758. [PMID: 34659381 PMCID: PMC8501382 DOI: 10.11909/j.issn.1671-5411.2021.09.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Non-invasive cardiac imaging has explored enormous advances in the last few decades. In particular, hybrid imaging represents the fusion of information from multiple imaging modalities, allowing to provide a more comprehensive dataset compared to traditional imaging techniques in patients with cardiovascular diseases. The complementary anatomical, functional and molecular information provided by hybrid systems are able to simplify the evaluation procedure of various pathologies in a routine clinical setting. The diagnostic capability of hybrid imaging modalities can be further enhanced by introducing novel and specific imaging biomarkers. The aim of this review is to cover the most recent advancements in radiotracers development for SPECT/CT, PET/CT, and PET/MRI for cardiovascular diseases.
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Abstract
PURPOSE OF REVIEW To present a method enabling in vivo quantification of tissue membrane potential (ΔΨT), a proxy of mitochondrial membrane potential (ΔΨm), to review the origin and role of ΔΨm, and to highlight potential applications of myocardial ΔΨT imaging. RECENT FINDINGS Radiolabelled lipophilic cations have been used for decades to measure ΔΨm in vitro. Using similar compounds labeled with positron emitters and appropriate compartment modeling, this technique now allows in vivo quantification of ΔΨT with positron emission tomography. Studies have confirmed the feasibility of measuring myocardial ΔΨT in both animals and humans. In addition, ΔΨT showed very low variability among healthy subjects, suggesting that this method could allow detection of relatively small pathological changes. In vivo assessment of myocardial ΔΨT provides a new tool to study the pathophysiology of cardiovascular diseases and has the potential to serve as a new biomarker to assess disease stage, prognosis, and response to therapy.
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7
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Salazar-Ramírez F, Ramos-Mondragón R, García-Rivas G. Mitochondrial and Sarcoplasmic Reticulum Interconnection in Cardiac Arrhythmia. Front Cell Dev Biol 2021; 8:623381. [PMID: 33585462 PMCID: PMC7876262 DOI: 10.3389/fcell.2020.623381] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 12/30/2020] [Indexed: 12/31/2022] Open
Abstract
Ca2+ plays a pivotal role in mitochondrial energy production, contraction, and apoptosis. Mitochondrial Ca2+-targeted fluorescent probes have demonstrated that mitochondria Ca2+ transients are synchronized with Ca2+ fluxes occurring in the sarcoplasmic reticulum (SR). The presence of specialized proteins tethering SR to mitochondria ensures the local Ca2+ flux between these organelles. Furthermore, communication between SR and mitochondria impacts their functionality in a bidirectional manner. Mitochondrial Ca2+ uptake through the mitochondrial Ca2+ uniplex is essential for ATP production and controlled reactive oxygen species levels for proper cellular signaling. Conversely, mitochondrial ATP ensures the proper functioning of SR Ca2+-handling proteins, which ensures that mitochondria receive an adequate supply of Ca2+. Recent evidence suggests that altered SR Ca2+ proteins, such as ryanodine receptors and the sarco/endoplasmic reticulum Ca2+ ATPase pump, play an important role in maintaining proper cardiac membrane excitability, which may be initiated and potentiated when mitochondria are dysfunctional. This recognized mitochondrial role offers the opportunity to develop new therapeutic approaches aimed at preventing cardiac arrhythmias in cardiac disease.
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Affiliation(s)
- Felipe Salazar-Ramírez
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Cátedra de Cardiología y Medicina Cardiovascular, Monterrey, Mexico
| | - Roberto Ramos-Mondragón
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States.,Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Gerardo García-Rivas
- Tecnologico de Monterrey, Escuela de Medicina y Ciencias de la Salud, Cátedra de Cardiología y Medicina Cardiovascular, Monterrey, Mexico.,TecSalud, Centro de Investigación Biomédica, Hospital Zambrano-Hellion, San Pedro Garza García, Mexico.,TecSalud, Centro de Medicina Funcional, Hospital Zambrano-Hellion, San Pedro Garza García, Mexico
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8
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Manolis AS, Manolis AA, Manolis TA, Apostolaki NE, Apostolopoulos EJ, Melita H, Katsiki N. Mitochondrial dysfunction in cardiovascular disease: Current status of translational research/clinical and therapeutic implications. Med Res Rev 2020; 41:275-313. [PMID: 32959403 DOI: 10.1002/med.21732] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 09/04/2020] [Accepted: 09/07/2020] [Indexed: 12/14/2022]
Abstract
Mitochondria provide energy to the cell during aerobic respiration by supplying ~95% of the adenosine triphosphate (ATP) molecules via oxidative phosphorylation. These organelles have various other functions, all carried out by numerous proteins, with the majority of them being encoded by nuclear DNA (nDNA). Mitochondria occupy ~1/3 of the volume of myocardial cells in adults, and function at levels of high-efficiency to promptly meet the energy requirements of the myocardial contractile units. Mitochondria have their own DNA (mtDNA), which contains 37 genes and is maternally inherited. Over the last several years, a variety of functions of these organelles have been discovered and this has led to a growing interest in their involvement in various diseases, including cardiovascular (CV) diseases. Mitochondrial dysfunction relates to the status where mitochondria cannot meet the demands of a cell for ATP and there is an enhanced formation of reactive-oxygen species. This dysfunction may occur as a result of mtDNA and/or nDNA mutations, but also as a response to aging and various disease and environmental stresses, leading to the development of cardiomyopathies and other CV diseases. Designing mitochondria-targeted therapeutic strategies aiming to maintain or restore mitochondrial function has been a great challenge as a result of variable responses according to the etiology of the disorder. There have been several preclinical data on such therapies, but clinical studies are scarce. A major challenge relates to the techniques needed to eclectically deliver the therapeutic agents to cardiac tissues and to damaged mitochondria for successful clinical outcomes. All these issues and progress made over the last several years are herein reviewed.
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Affiliation(s)
- Antonis S Manolis
- First Department of Cardiology, Athens University School of Medicine, Athens, Greece
| | | | | | | | | | | | - Niki Katsiki
- First Department of Internal Medicine, Division of Endocrinology and Metabolism, Diabetes Center, Medical School, AHEPA University Hospital, Thessaloniki, Greece
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9
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Pelletier-Galarneau M, Petibon Y, Ma C, Han P, Kim SJW, Detmer FJ, Yokell D, Guehl N, Normandin M, El Fakhri G, Alpert NM. In vivo quantitative mapping of human mitochondrial cardiac membrane potential: a feasibility study. Eur J Nucl Med Mol Imaging 2020; 48:414-420. [PMID: 32719915 DOI: 10.1007/s00259-020-04878-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 05/19/2020] [Indexed: 12/30/2022]
Abstract
PURPOSE Alteration in mitochondrial membrane potential (ΔΨm) is an important feature of many pathologic processes, including heart failure, cardiotoxicity, ventricular arrhythmia, and myocardial hypertrophy. We present the first in vivo, non-invasive, assessment of regional ΔΨm in the myocardium of normal human subjects. METHODS Thirteen healthy subjects were imaged using [18F]-triphenylphosphonium ([18F]TPP+) on a PET/MR scanner. The imaging protocol consisted of a bolus injection of 300 MBq followed by a 120-min infusion of 0.6 MBq/min. A 60 min, dynamic PET acquisition was started 1 h after bolus injection. The extracellular space fraction (fECS) was simultaneously measured using MR T1-mapping images acquired at baseline and 15 min after gadolinium injection with correction for the subject's hematocrit level. Serial venous blood samples were obtained to calculate the plasma tracer concentration. The tissue membrane potential (ΔΨT), a proxy of ΔΨm, was calculated from the myocardial tracer concentration at secular equilibrium, blood concentration, and fECS measurements using a model based on the Nernst equation. RESULTS In 13 healthy subjects, average tissue membrane potential (ΔΨT), representing the sum of cellular membrane potential (ΔΨc) and ΔΨm, was - 160.7 ± 3.7 mV, in excellent agreement with previous in vitro assessment. CONCLUSION In vivo quantification of the mitochondrial function has the potential to provide new diagnostic and prognostic information for several cardiac diseases as well as allowing therapy monitoring. This feasibility study lays the foundation for further investigations to assess these potential roles. Clinical trial identifier: NCT03265431.
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Affiliation(s)
- Matthieu Pelletier-Galarneau
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, 125 Nashua Street, #6604, Boston, MA, 02114, USA
| | - Yoann Petibon
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, 125 Nashua Street, #6604, Boston, MA, 02114, USA
| | - Chao Ma
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, 125 Nashua Street, #6604, Boston, MA, 02114, USA
| | - Paul Han
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, 125 Nashua Street, #6604, Boston, MA, 02114, USA
| | - Sally Ji Who Kim
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, 125 Nashua Street, #6604, Boston, MA, 02114, USA
| | - Felicitas J Detmer
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, 125 Nashua Street, #6604, Boston, MA, 02114, USA
| | - Daniel Yokell
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, 125 Nashua Street, #6604, Boston, MA, 02114, USA
| | - Nicolas Guehl
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, 125 Nashua Street, #6604, Boston, MA, 02114, USA
| | - Marc Normandin
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, 125 Nashua Street, #6604, Boston, MA, 02114, USA
| | - Georges El Fakhri
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, 125 Nashua Street, #6604, Boston, MA, 02114, USA.
| | - Nathaniel M Alpert
- Department of Radiology, Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, 125 Nashua Street, #6604, Boston, MA, 02114, USA.
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10
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Alpert NM, Pelletier-Galarneau M, Kim SJW, Petibon Y, Sun T, Ramos-Torres KM, Normandin MD, El Fakhri G. In-vivo Imaging of Mitochondrial Depolarization of Myocardium With Positron Emission Tomography and a Proton Gradient Uncoupler. Front Physiol 2020; 11:491. [PMID: 32499721 PMCID: PMC7243673 DOI: 10.3389/fphys.2020.00491] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 04/21/2020] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND We recently reported a method using positron emission tomography (PET) and the tracer 18F-labeled tetraphenylphosphonium (18F-TPP+) for mapping the tissue (i.e., cellular plus mitochondrial) membrane potential (ΔΨT) in the myocardium. The purpose of this work is to provide additional experimental evidence that our methods can be used to observe transient changes in the volume of distribution for 18F-TPP+ and mitochondrial membrane potential (ΔΨm). METHODS We tested these hypotheses by measuring decreases of 18F-TPP+ concentration elicited when a proton gradient uncoupler, BAM15, is administered by intracoronary infusion during PET scanning. BAM15 is the first proton gradient uncoupler shown to affect the mitochondrial membrane without affecting the cellular membrane potential. Preliminary dose response experiments were conducted in two pigs to determine the concentration of BAM15 infusate necessary to perturb the 18F-TPP+ concentration. More definitive experiments were performed in two additional pigs, in which we administered an intravenous bolus plus infusion of 18F-TPP+ to reach secular equilibrium followed by an intracoronary infusion of BAM15. RESULTS Intracoronary BAM15 infusion led to a clear decrease in 18F-TPP+ concentration, falling to a lower level, and then recovering. A second BAM15 infusion reduced the 18F-TPP+ level in a similar fashion. We observed a maximum depolarization of 10 mV as a result of the BAM15 infusion. SUMMARY This work provides evidence that the total membrane potential measured with 18F-TPP+ PET is sensitive to temporal changes in mitochondrial membrane potential.
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Affiliation(s)
- Nathaniel M. Alpert
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Matthieu Pelletier-Galarneau
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
- Department of Medical Imaging, Montreal Heart Institute, Montreal, QC, Canada
| | - Sally Ji Who Kim
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Yoann Petibon
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Tao Sun
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Karla M. Ramos-Torres
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Marc D. Normandin
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
| | - Georges El Fakhri
- Gordon Center for Medical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States
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11
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Chadda KR, Fazmin IT, Ahmad S, Valli H, Edling CE, Huang CLH, Jeevaratnam K. Arrhythmogenic mechanisms of obstructive sleep apnea in heart failure patients. Sleep 2019; 41:5054592. [PMID: 30016501 DOI: 10.1093/sleep/zsy136] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 07/13/2018] [Indexed: 01/01/2023] Open
Abstract
Heart failure (HF) affects 23 million people worldwide and results in 300000 annual deaths. It is associated with many comorbidities, such as obstructive sleep apnea (OSA), and risk factors for both conditions overlap. Eleven percent of HF patients have OSA and 7.7% of OSA patients have left ventricular ejection fraction <50% with arrhythmias being a significant comorbidity in HF and OSA patients. Forty percent of HF patients develop atrial fibrillation (AF) and 30%-50% of deaths from cardiac causes in HF patients are from sudden cardiac death. OSA is prevalent in 32%-49% of patients with AF and there is a dose-dependent relationship between OSA severity and resistance to anti-arrhythmic therapies. HF and OSA lead to various downstream arrhythmogenic mechanisms, including metabolic derangement, remodeling, inflammation, and autonomic imbalance. (1) Metabolic derangement and production of reactive oxidative species increase late Na+ currents, decrease outward K+ currents and downregulate connexin-43 and cell-cell coupling. (2) remodeling also features downregulated K+ currents in addition to decreased Na+/K+ ATPase currents, altered Ca2+ homeostasis, and increased density of If current. (3) Chronic inflammation leads to downregulation of both Nav1.5 channels and K+ channels, altered Ca2+ homeostasis and reduced cellular coupling from alterations of connexin expression. (4) Autonomic imbalance causes arrhythmias by evoking triggered activity through increased Ca2+ transients and reduction of excitation wavefront wavelength. Thus, consideration of these multiple pathophysiological pathways (1-4) will enable the development of novel therapeutic strategies that can be targeted against arrhythmias in the context of complex disease, such as the comorbidities of HF and OSA.
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Affiliation(s)
- Karan R Chadda
- Faculty of Health and Medical Science, University of Surrey, Guildford, United Kingdom.,Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, United Kingdom
| | - Ibrahim T Fazmin
- Faculty of Health and Medical Science, University of Surrey, Guildford, United Kingdom.,Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, United Kingdom
| | - Shiraz Ahmad
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, United Kingdom
| | - Haseeb Valli
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, United Kingdom
| | - Charlotte E Edling
- Faculty of Health and Medical Science, University of Surrey, Guildford, United Kingdom
| | - Christopher L-H Huang
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, United Kingdom.,Department of Biochemistry, Hopkins Building, University of Cambridge, Cambridge, United Kingdom
| | - Kamalan Jeevaratnam
- Faculty of Health and Medical Science, University of Surrey, Guildford, United Kingdom.,Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, United Kingdom
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12
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Alpert NM, Guehl N, Ptaszek L, Pelletier-Galarneau M, Ruskin J, Mansour MC, Wooten D, Ma C, Takahashi K, Zhou Y, Shoup TM, Normandin MD, El Fakhri G. Quantitative in vivo mapping of myocardial mitochondrial membrane potential. PLoS One 2018; 13:e0190968. [PMID: 29338024 PMCID: PMC5770041 DOI: 10.1371/journal.pone.0190968] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 12/22/2017] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Mitochondrial membrane potential (ΔΨm) arises from normal function of the electron transport chain. Maintenance of ΔΨm within a narrow range is essential for mitochondrial function. Methods for in vivo measurement of ΔΨm do not exist. We use 18F-labeled tetraphenylphosphonium (18F-TPP+) to measure and map the total membrane potential, ΔΨT, as the sum of ΔΨm and cellular (ΔΨc) electrical potentials. METHODS Eight pigs, five controls and three with a scar-like injury, were studied. Pigs were studied with a dynamic PET scanning protocol to measure 18F-TPP+ volume of distribution, VT. Fractional extracellular space (fECS) was measured in 3 pigs. We derived equations expressing ΔΨT as a function of VT and the volume-fractions of mitochondria and fECS. Seventeen segment polar maps and parametric images of ΔΨT were calculated in millivolts (mV). RESULTS In controls, mean segmental ΔΨT = -129.4±1.4 mV (SEM). In pigs with segmental tissue injury, ΔΨT was clearly separated from control segments but variable, in the range -100 to 0 mV. The quality of ΔΨT maps was excellent, with low noise and good resolution. Measurements of ΔΨT in the left ventricle of pigs agree with previous in in-vitro measurements. CONCLUSIONS We have analyzed the factors affecting the uptake of voltage sensing tracers and developed a minimally invasive method for mapping ΔΨT in left ventricular myocardium of pigs. ΔΨT is computed in absolute units, allowing for visual and statistical comparison of individual values with normative data. These studies demonstrate the first in vivo application of quantitative mapping of total tissue membrane potential, ΔΨT.
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Affiliation(s)
- Nathaniel M. Alpert
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Nicolas Guehl
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Leon Ptaszek
- Cardiac Arrhythmia Service, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Matthieu Pelletier-Galarneau
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jeremy Ruskin
- Cardiac Arrhythmia Service, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Moussa C. Mansour
- Cardiac Arrhythmia Service, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Dustin Wooten
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Chao Ma
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Kazue Takahashi
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Yun Zhou
- The Russell H. Morgan Department of Radiology and Radiological Science, School of Medicine Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Timothy M. Shoup
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Marc D. Normandin
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Georges El Fakhri
- Gordon Center for Medical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
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Emelyanova L, Ashary Z, Cosic M, Negmadjanov U, Ross G, Rizvi F, Olet S, Kress D, Sra J, Tajik AJ, Holmuhamedov EL, Shi Y, Jahangir A. Selective downregulation of mitochondrial electron transport chain activity and increased oxidative stress in human atrial fibrillation. Am J Physiol Heart Circ Physiol 2016; 311:H54-63. [PMID: 27199126 PMCID: PMC4967212 DOI: 10.1152/ajpheart.00699.2015] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 04/27/2016] [Indexed: 12/19/2022]
Abstract
Mitochondria are critical for maintaining normal cardiac function, and a deficit in mitochondrial energetics can lead to the development of the substrate that promotes atrial fibrillation (AF) and its progression. However, the link between mitochondrial dysfunction and AF in humans is still not fully defined. The aim of this study was to elucidate differences in the functional activity of mitochondrial oxidative phosphorylation (OXPHOS) complexes and oxidative stress in right atrial tissue from patients without (non-AF) and with AF (AF) who were undergoing open-heart surgery and were not significantly different for age, sex, major comorbidities, and medications. The overall functional activity of the electron transport chain (ETC), NADH:O2 oxidoreductase activity, was reduced by 30% in atrial tissue from AF compared with non-AF patients. This was predominantly due to a selective reduction in complex I (0.06 ± 0.007 vs. 0.09 ± 0.006 nmol·min(-1)·citrate synthase activity(-1), P = 0.02) and II (0.11 ± 0.012 vs. 0.16 ± 0.012 nmol·min(-1)·citrate synthase activity(-1), P = 0.003) functional activity in AF patients. Conversely, complex V activity was significantly increased in AF patients (0.21 ± 0.027 vs. 0.12 ± 0.01 nmol·min(-1)·citrate synthase activity(-1), P = 0.005). In addition, AF patients exhibited a higher oxidative stress with increased production of mitochondrial superoxide (73 ± 17 vs. 11 ± 2 arbitrary units, P = 0.03) and 4-hydroxynonenal level (77.64 ± 30.2 vs. 9.83 ± 2.83 ng·mg(-1) protein, P = 0.048). Our findings suggest that AF is associated with selective downregulation of ETC activity and increased oxidative stress that can contribute to the progression of the substrate for AF.
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Affiliation(s)
- Larisa Emelyanova
- Sheikh Khalifa bin Hamad Al Thani Center for Integrative Research on Cardiovascular Aging, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin
| | - Zain Ashary
- Sheikh Khalifa bin Hamad Al Thani Center for Integrative Research on Cardiovascular Aging, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin
| | - Milanka Cosic
- Sheikh Khalifa bin Hamad Al Thani Center for Integrative Research on Cardiovascular Aging, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin
| | - Ulugbek Negmadjanov
- Sheikh Khalifa bin Hamad Al Thani Center for Integrative Research on Cardiovascular Aging, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin
| | - Gracious Ross
- Sheikh Khalifa bin Hamad Al Thani Center for Integrative Research on Cardiovascular Aging, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin
| | - Farhan Rizvi
- Sheikh Khalifa bin Hamad Al Thani Center for Integrative Research on Cardiovascular Aging, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin
| | - Susan Olet
- Patient-Centered Research, Aurora Research Institute, Aurora Health Care, Milwaukee, Wisconsin; and
| | - David Kress
- Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin
| | - Jasbir Sra
- Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin
| | - A Jamil Tajik
- Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin
| | - Ekhson L Holmuhamedov
- Sheikh Khalifa bin Hamad Al Thani Center for Integrative Research on Cardiovascular Aging, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin
| | - Yang Shi
- Sheikh Khalifa bin Hamad Al Thani Center for Integrative Research on Cardiovascular Aging, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin
| | - Arshad Jahangir
- Sheikh Khalifa bin Hamad Al Thani Center for Integrative Research on Cardiovascular Aging, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin; Patient-Centered Research, Aurora Research Institute, Aurora Health Care, Milwaukee, Wisconsin; and Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke's Medical Centers, Milwaukee, Wisconsin
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