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Strutynska N, Strutynskyi R, Mys L, Luchkova A, Korkach Y, Goshovska Y, Chorna S, Sagach V. Exercise restores endogenous H 2 S synthesis and mitochondrial function in the heart of old rats. Eur J Clin Invest 2022; 52:e13829. [PMID: 35778885 DOI: 10.1111/eci.13829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 06/27/2022] [Accepted: 06/29/2022] [Indexed: 12/29/2022]
Abstract
BACKGROUND Ageing is accompanied by a decrease in endogenous hydrogen sulphide (H2 S) synthesis and the development of mitochondrial dysfunction. The aim of our work was to study the possible participation of exercise training-induced regulation of endogenous H2 S production in the restoration of mitochondrial function in old rats. MATERIALS AND METHODS Male rats were divided into three groups: adult, old and exercise-trained old. Exercise training of old rats was performed for 4 weeks. The mRNA expression cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST) were determined using reverse transcription and real-time polymerase chain reaction analysis. Mitochondrial dysfunction was determined by mPTP opening, which was investigated by spectrophotometric registration of the swelling of mitochondria isolated from the rat heart. We also studied the effect of exercise on H2 S content, oxidative stress and mtNOS activity. RESULTS Exercise training in old animals significantly increased the expression of H2 S-synthesizing enzymes CSE and 3-MST and restored endogenous H2 S production in cardiac tissue and cardiac mitochondria to levels of adult animals. In addition, the training significantly reduced oxidative stress in old rats, in particular the rate of formation of •O2 - and H2 O2 , diene conjugates and malondialdehyde levels in the mitochondria of the heart. Simultaneously, in the hearts of these animals, resistance of mPTP to the inducer of its opening of calcium ions was increased. CONCLUSIONS Thus, exercise training restores endogenous H2 S production, and significantly reduces oxidative stress in cardiac mitochondria of old rats that are associated with the inhibition of calcium-induced mPTP opening as an indicator of mitochondrial dysfunction.
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Affiliation(s)
- Nataliіa Strutynska
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Ruslan Strutynskyi
- Department of General and Molecular Pathophysiology, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Lidiia Mys
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Alina Luchkova
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Yuliia Korkach
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Yulia Goshovska
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Snizhana Chorna
- Department of Physiology and Cell Biology, Ohio State University, Columbus, Ohio, USA
| | - Vadym Sagach
- Department of Blood Circulation, Bogomoletz Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
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Analysis of Mitochondrial Function, Structure, and Intracellular Organization In Situ in Cardiomyocytes and Skeletal Muscles. Int J Mol Sci 2022; 23:ijms23042252. [PMID: 35216368 PMCID: PMC8876605 DOI: 10.3390/ijms23042252] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 01/31/2022] [Accepted: 02/07/2022] [Indexed: 01/27/2023] Open
Abstract
Analysis of the function, structure, and intracellular organization of mitochondria is important for elucidating energy metabolism and intracellular energy transfer. In addition, basic and clinically oriented studies that investigate organ/tissue/cell dysfunction in various human diseases, including myopathies, cardiac/brain ischemia-reperfusion injuries, neurodegenerative diseases, cancer, and aging, require precise estimation of mitochondrial function. It should be noted that the main metabolic and functional characteristics of mitochondria obtained in situ (in permeabilized cells and tissue samples) and in vitro (in isolated organelles) are quite different, thereby compromising interpretations of experimental and clinical data. These differences are explained by the existence of the mitochondrial network, which possesses multiple interactions between the cytoplasm and other subcellular organelles. Metabolic and functional crosstalk between mitochondria and extra-mitochondrial cellular environments plays a crucial role in the regulation of mitochondrial metabolism and physiology. Therefore, it is important to analyze mitochondria in vivo or in situ without their isolation from the natural cellular environment. This review summarizes previous studies and discusses existing approaches and methods for the analysis of mitochondrial function, structure, and intracellular organization in situ.
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Jang S, Chapa-Dubocq XR, Fossati S, Javadov S. Analysis of Mitochondrial Calcium Retention Capacity in Cultured Cells: Permeabilized Cells Versus Isolated Mitochondria. Front Physiol 2021; 12:773839. [PMID: 34950052 PMCID: PMC8688924 DOI: 10.3389/fphys.2021.773839] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/17/2021] [Indexed: 12/04/2022] Open
Abstract
In response to various pathological stimuli, such as oxidative and energy stress accompanied by high Ca2+, mitochondria undergo permeability transition (PT) leading to the opening of the non-selective PT pores (PTP) in the inner mitochondrial membrane. Opening of the pores at high conductance allows the passage of ions and solutes <1.5 kD across the membrane, that increases colloid osmotic pressure in the matrix leading to excessive mitochondrial swelling. Calcium retention capacity (CRC) reflects maximum Ca2+ overload of mitochondria that occurs just before PTP opening. Quantification of CRC is important for elucidating the effects of different pathological stimuli and the efficacy of pharmacological agents on the mitochondria. Here, we performed a comparative analysis of CRC in mitochondria isolated from H9c2 cardioblasts, and in permeabilized H9c2 cells in situ to highlight the strengths and weaknesses of the CRC technique in isolated cell mitochondria vs. permeabilized cells. The cells were permeabilized by digitonin or saponin, and the Ca2+-sensitive fluorescence probe Calcium Green-5N was used in both preparations. Results demonstrated the interference of dye-associated fluorescence signals with saponin and the adverse effects of digitonin on mitochondria at high concentrations. Analysis of the CRC in permeabilized cells revealed a higher CRC in the saponin-permeabilized cells in comparison with the digitonin-permeabilized cells. In addition, the mitochondrial CRC in saponin-permeabilized cells was higher than in isolated mitochondria. Altogether, these data demonstrate that the quantification of the mitochondrial CRC in cultured cells permeabilized by saponin has more advantages compared to the isolated mitochondria.
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Affiliation(s)
- Sehwan Jang
- Department of Physiology, University of Puerto Rico School of Medicine, San Juan, PR, United States
| | - Xavier R Chapa-Dubocq
- Department of Physiology, University of Puerto Rico School of Medicine, San Juan, PR, United States
| | - Silvia Fossati
- Alzheimer's Center at Temple, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Sabzali Javadov
- Department of Physiology, University of Puerto Rico School of Medicine, San Juan, PR, United States
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4
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Penna C, Alloatti G, Crisafulli A. Mechanisms Involved in Cardioprotection Induced by Physical Exercise. Antioxid Redox Signal 2020; 32:1115-1134. [PMID: 31892282 DOI: 10.1089/ars.2019.8009] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Significance: Regular exercise training can reduce myocardial damage caused by acute ischemia/reperfusion (I/R). Exercise can reproduce the phenomenon of ischemic preconditioning, due to the capacity of brief periods of ischemia to reduce myocardial damage caused by acute I/R. In addition, exercise may also activate the multiple kinase cascade responsible for cardioprotection even in the absence of ischemia. Recent Advances: Animal and human studies highlighted the fact that, besides to reduce risk factors related to cardiovascular disease, the beneficial effects of exercise are also due to its ability to induce conditioning of the heart. Exercise behaves as a physiological stress that triggers beneficial adaptive cellular responses, inducing a protective phenotype in the heart. The factors contributing to the exercise-induced heart preconditioning include stimulation of the anti-radical defense system and nitric oxide production, opioids, myokines, and adenosine-5'-triphosphate (ATP) dependent potassium channels. They appear to be also involved in the protective effect exerted by exercise against cardiotoxicity related to chemotherapy. Critical Issues and Future Directions: Although several experimental evidences on the protective effect of exercise have been obtained, the mechanisms underlying this phenomenon have not yet been fully clarified. Further studies are warranted to define precise exercise prescriptions in patients at risk of myocardial infarction or undergoing chemotherapy.
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Affiliation(s)
- Claudia Penna
- National Institute for Cardiovascular Research (INRC), Bologna, Italy.,Department of Clinical and Biological Sciences, University of Turin, Torino, Italy
| | | | - Antonio Crisafulli
- Department of Medical Sciences and Public Health, Sports Physiology Lab., University of Cagliari, Cagliari, Italy
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Ziolkowski W, Flis DJ, Halon M, Vadhana DMS, Olek RA, Carloni M, Antosiewicz J, Kaczor JJ, Gabbianelli R. Prolonged swimming promotes cellular oxidative stress and p66Shc phosphorylation, but does not induce oxidative stress in mitochondria in the rat heart. Free Radic Res 2014; 49:7-16. [DOI: 10.3109/10715762.2014.968147] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Ziolkowski W, Vadhana M S D, Kaczor JJ, Olek RA, Flis DJ, Halon M, Wozniak M, Fedeli D, Carloni M, Antosiewicz J, Gabbianelli R. Exercise-induced heart mitochondrial cholesterol depletion influences the inhibition of mitochondrial swelling. Exp Physiol 2013; 98:1457-68. [PMID: 23733522 DOI: 10.1113/expphysiol.2013.073007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The significance of the reduction of the cholesterol pool in heart mitochondria after exercise is still unknown. Recently, published data have suggested that cholesterol may influence the components of mitochondrial contact site and affect mitochondrial swelling. Therefore, the aim of this study was to determine whether the decreased cholesterol content in heart mitochondria caused by prolonged swimming may provoke changes in their bioenergetics and result in an increased resistance to calcium chloride-induced mitochondrial swelling. Male Wistar rats were divided into a sedentary control group and an exercise group. The rats exercised for 3 h, burdened with an additional 3% of their body weight. Their hearts were removed immediately after completing the exercise. The left ventricle was divided and used for experiments. Mitochondrial cholesterol content, membrane fluidity and mitochondrial bioenergetics were measured in the control and exercised rat heart mitochondria. To assess whether mitochondrial modifications are linked to disruption of lipid microdomains, methyl-β-cyclodextrin, a well-known lipid microdomain-disrupting agent and cholesterol chelator, was applied to the mitochondria of the control group. Cholesterol depletion, increased membrane fluidity and increased resistance to calcium chloride-induced swelling were observed in postexercise heart crude mitochondrial fraction. Similar results were achieved in control mitochondria treated with 2% methyl-β-cyclodextrin. All of the mitochondrial bioenergetics parameters were similar between the groups. Therefore, the disruption of raft-like microdomains appears to be an adaptive change in the rat heart following exercise.
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Affiliation(s)
- Wieslaw Ziolkowski
- W. Ziolkowski: Department of Biochemistry, Gdansk University of Physical Education and Sport, 1 K. Gorskiego Street, 80-336 Gdansk, Poland.
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7
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Inhibition of the Mitochondrial Permeability Transition for Cytoprotection: Direct versus Indirect Mechanisms. Biochem Res Int 2012; 2012:213403. [PMID: 22675634 PMCID: PMC3364550 DOI: 10.1155/2012/213403] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 02/07/2012] [Indexed: 11/17/2022] Open
Abstract
Mitochondria are fascinating organelles, which fulfill multiple cellular functions, as diverse as energy production, fatty acid β oxidation, reactive oxygen species (ROS) production and detoxification, and cell death regulation. The coordination of these functions relies on autonomous mitochondrial processes as well as on sustained cross-talk with other organelles and/or the cytosol. Therefore, this implies a tight regulation of mitochondrial functions to ensure cell homeostasis. In many diseases (e.g., cancer, cardiopathies, nonalcoholic fatty liver diseases, and neurodegenerative diseases), mitochondria can receive harmful signals, dysfunction and then, participate to pathogenesis. They can undergo either a decrease of their bioenergetic function or a process called mitochondrial permeability transition (MPT) that can coordinate cell death execution. Many studies present evidence that protection of mitochondria limits disease progression and severity. Here, we will review recent strategies to preserve mitochondrial functions via direct or indirect mechanisms of MPT inhibition. Thus, several mitochondrial proteins may be considered for cytoprotective-targeted therapies.
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8
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Ascah A, Khairallah M, Daussin F, Bourcier-Lucas C, Godin R, Allen BG, Petrof BJ, Des Rosiers C, Burelle Y. Stress-induced opening of the permeability transition pore in the dystrophin-deficient heart is attenuated by acute treatment with sildenafil. Am J Physiol Heart Circ Physiol 2011; 300:H144-53. [DOI: 10.1152/ajpheart.00522.2010] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Susceptibility of cardiomyocytes to stress-induced damage has been implicated in the development of cardiomyopathy in Duchenne muscular dystrophy, a disease caused by the lack of the cytoskeletal protein dystrophin in which heart failure is frequent. However, the factors underlying the disease progression are unclear and treatments are limited. Here, we tested the hypothesis of a greater susceptibility to the opening of the mitochondrial permeability transition pore (PTP) in hearts from young dystrophic ( mdx) mice (before the development of overt cardiomyopathy) when subjected to a stress protocol and determined whether the prevention of a PTP opening is involved in the cardioprotective effect of sildenafil, which we have previously reported in mdx mice. Using the 2-deoxy-[3H]glucose method to quantify the PTP opening in ex vivo perfused hearts, we demonstrate that when compared with those of controls, the hearts from young mdx mice subjected to ischemia-reperfusion (I/R) display an excessive PTP opening as well as enhanced activation of cell death signaling, mitochondrial oxidative stress, cardiomyocyte damage, and poorer recovery of contractile function. Functional analyses in permeabilized cardiac fibers from nonischemic hearts revealed that in vitro mitochondria from mdx hearts display normal respiratory function and reactive oxygen species handling, but enhanced Ca2+ uptake velocity and premature opening of the PTP, which may predispose to I/R-induced injury. The administration of a single dose of sildenafil to mdx mice before I/R prevented excessive PTP opening and its downstream consequences and reduced tissue Ca2+ levels. Furthermore, mitochondrial Ca2+ uptake velocity was reduced following sildenafil treatment. In conclusion, beyond our documentation that an increased susceptibility to the opening of the mitochondrial PTP in the mdx heart occurs well before clinical signs of overt cardiomyopathy, our results demonstrate that sildenafil, which is already administered in other pediatric populations and is reported safe and well tolerated, provides efficient protection against this deleterious event, likely by reducing cellular Ca2+ loading and mitochondrial Ca2+ uptake.
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Affiliation(s)
| | | | | | | | | | - Bruce G. Allen
- Montreal Heart Institute and
- Medicine, Université de Montréal; and
| | - Basil J. Petrof
- Meakins-Christie Laboratories and Respiratory Division, McGill University, Montreal, Quebec, Canada
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9
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Acute exercise protects against calcium-induced cardiac mitochondrial permeability transition pore opening in doxorubicin-treated rats. Clin Sci (Lond) 2010; 120:37-49. [PMID: 20666733 DOI: 10.1042/cs20100254] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The use of DOX (doxorubicin), an antibiotic used in oncological treatments, is limited by a dose-related cardiotoxicity against which acute exercise is protective. However, the mitochondrial-related mechanisms of this protection remain unknown. Therefore the present study aimed to determine the effects of an acute endurance exercise bout performed 24 h before DOX treatment on heart and liver mitochondrial function. A total of 20 adult male Wistar rats were divided into groups as follows: non-exercised with saline (NE + SAL), non-exercised DOX-treated (NE + DOX), exercised with saline (EX + SAL) and exercised DOX-treated (EX + DOX). The animals performed a 60 min exercise bout on a treadmill or remained sedentary 24 h before receiving either a DOX bolus (20 mg/kg of body weight) or saline. Heart and liver mitochondrial function [oxygen consumption, membrane potential (DeltaPsi) and cyclosporin-A-sensitive calcium-induced MPTP (mitochondrial permeability transition pore) opening] were evaluated. The activities of the respiratory complex, Mn-SOD (superoxide dismutase), caspases 3 and 9, as well as the levels of ANT (adenine nucleotide translocase), VDAC (voltage-dependent anion channel), CypD (cyclophilin D), Bax and Bcl-2, were measured. Acute exercise prevented the decreased cardiac mitochondrial function (state 3, phosphorylative lagphase; maximal DeltaPsi generated both with complex I- and II-linked substrates and calcium-induced MPTP opening) induced by DOX treatment. Exercise also prevented the DOX-induced decreased activity of cardiac mitochondrial chain complexes I and V, and increased caspase 3 and 9 activities. DOX administration and exercise caused increased cardiac mitochondrial SOD activity. Exercise ameliorated liver mitochondrial complex activities. No alterations were observed in the measured MPTP and apoptosis-related proteins in heart and liver mitochondria. The results demonstrate that acute exercise protects against cardiac mitochondrial dysfunction, preserving mitochondrial phosphorylation capacity and attenuating DOX-induced decreased tolerance to MPTP opening.
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10
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Halestrap AP, Pasdois P. The role of the mitochondrial permeability transition pore in heart disease. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1787:1402-15. [PMID: 19168026 DOI: 10.1016/j.bbabio.2008.12.017] [Citation(s) in RCA: 277] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 12/19/2008] [Accepted: 12/20/2008] [Indexed: 01/17/2023]
Abstract
Like Dr. Jeckyll and Mr. Hyde, mitochondria possess two distinct persona. Under normal physiological conditions they synthesise ATP to meet the energy needs of the beating heart. Here calcium acts as a signal to balance the rate of ATP production with ATP demand. However, when the heart is overloaded with calcium, especially when this is accompanied by oxidative stress, mitochondria embrace their darker side, and induce necrotic cell death of the myocytes. This happens acutely in reperfusion injury and chronically in congestive heart failure. Here calcium overload, adenine nucleotide depletion and oxidative stress combine forces to induce the opening of a non-specific pore in the mitochondrial membrane, known as the mitochondrial permeability transition pore (mPTP). The molecular nature of the mPTP remains controversial but current evidence implicates a matrix protein, cyclophilin-D (CyP-D) and two inner membrane proteins, the adenine nucleotide translocase (ANT) and the phosphate carrier (PiC). Inhibition of mPTP opening can be achieved with inhibitors of each component, but targeting CyP-D with cyclosporin A (CsA) and its non-immunosuppressive analogues is the best described. In animal models, inhibition of mPTP opening by either CsA or genetic ablation of CyP-D provides strong protection from both reperfusion injury and congestive heart failure. This confirms the mPTP as a promising drug target in human cardiovascular disease. Indeed, the first clinical trials have shown CsA treatment improves recovery after treatment of a coronary thrombosis with angioplasty.
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Affiliation(s)
- Andrew P Halestrap
- Department of Biochemistry and Bristol Heart Institute, University of Bristol, School of Medical Sciences, University Walk, Bristol BS8 1TD, UK.
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Burelle Y, Khairallah M, Ascah A, Allen BG, Deschepper CF, Petrof BJ, Des Rosiers C. Alterations in mitochondrial function as a harbinger of cardiomyopathy: lessons from the dystrophic heart. J Mol Cell Cardiol 2009; 48:310-21. [PMID: 19769982 DOI: 10.1016/j.yjmcc.2009.09.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Revised: 09/03/2009] [Accepted: 09/09/2009] [Indexed: 10/20/2022]
Abstract
While compelling evidence supports the central role of mitochondrial dysfunction in the pathogenesis of heart failure, there is comparatively less information available on mitochondrial alterations that occur prior to failure. Building on our recent work with the dystrophin-deficient mdx mouse heart, this review focuses on how early changes in mitochondrial functional phenotype occur prior to overt cardiomyopathy and may be a determinant for the development of adverse cardiac remodelling leading to failure. These include alterations in energy substrate utilization and signalling of cell death through increased permeability of mitochondrial membranes, which may result from abnormal calcium handling, and production of reactive oxygen species. Furthermore, we will discuss evidence supporting the notion that these alterations in the dystrophin-deficient heart may represent an early "subclinical" signature of a defective nitric oxide/cGMP signalling pathway, as well as the potential benefit of mitochondria-targeted therapies. While the mdx mouse is an animal model of Duchenne muscular dystrophy (DMD), changes in the structural integrity of dystrophin, the mutated cytoskeletal protein responsible for DMD, have also recently been implicated as a common mechanism for contractile dysfunction in heart failure. In fact, altogether our findings support a critical role for dystrophin in maintaining optimal coupling between metabolism and contraction in the heart.
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Affiliation(s)
- Yan Burelle
- Department of Kinesiology, Université de Montréal, Montreal, Quebec, Canada
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Javadov S, Karmazyn M, Escobales N. Mitochondrial permeability transition pore opening as a promising therapeutic target in cardiac diseases. J Pharmacol Exp Ther 2009; 330:670-8. [PMID: 19509316 DOI: 10.1124/jpet.109.153213] [Citation(s) in RCA: 180] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
In addition to their central role in ATP synthesis, mitochondria play a critical role in cell death. Oxidative stress accompanied by calcium overload, ATP depletion, and elevated phosphate levels induces mitochondrial permeability transition (MPT) with formation of nonspecific MPT pores (MPTP) in the inner mitochondrial membrane. Pore opening results in mitochondrial dysfunction with uncoupled oxidative phosphorylation and ATP hydrolysis, ultimately leading to cell death. For the past 20 years, three proteins have been accepted as key structural components of the MPTP: adenine nucleotide translocase (ANT) in the inner membrane, cyclophilin D (CyP-D) in the matrix, and the voltage-dependent anion channel (VDAC) in the outer membrane. However, most recent studies have questioned the molecular identity of the pores. Genetic studies have eliminated the VDAC as an essential component of MPTP and attributed a regulatory (rather than structural) role to ANT. Currently, the phosphate carrier appears to play a crucial role in MPTP formation. MPTP opening has been examined extensively in cardiac pathological conditions, including ischemia/reperfusion as well as heart failure. Accordingly, MPTP is accepted as a therapeutic target for both pharmacological and conditional strategies to block pore formation by direct interaction with MPTP components or indirectly by decreasing MPTP inducers. Inhibition of MPTP opening by reduction of CyP-D activity by nonimmunosuppressive analogs of cyclosporine A or sanglifehrin A, as well as attenuation of reactive oxygen species accumulation through mitochondria-targeted antioxidants, is the most promising. This review outlines our current knowledge of the structure and function of the MPTP and describes possible approaches for cardioprotection.
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Affiliation(s)
- Sabzali Javadov
- Department of Physiology, School of Medicine, University of Puerto Rico, P. O. Box 365067, San Juan, PR.
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13
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Abstract
It is now well established that exercise can result in cardioprotection against ischemia-reperfusion (I-R) injury; however, the adaptations within the heart that provide the protection are still in doubt. The cytoprotective proteins receiving the most attention to date are antioxidant enzymes and heat shock proteins. The extent of I-R injury is dependent on the interactions of several events, including energy depletion, metabolite accumulation, oxidant stress, and calcium overload. Adaptations that directly influence any of these could affect I-R outcome. Thus, the exercise-induced cardioprotective phenotype is likely to include additional cytoprotective proteins beyond antioxidant enzymes or heat shock proteins. In this review, we will consider evidence for some of these in the cytosol, mitochondria, and sarcolemma of the cardiomyocyte. We will not consider potentially important adaptations within vascular tissue or the autonomic nervous system. Results of recent studies support the hypothesis that exercise leads to cardioprotective adaptations that are unique from other forms of preconditioning against I-R injury.
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Affiliation(s)
- Joseph W Starnes
- Cardiac Metabolism Laboratory, Department of Kinesiology and Health Education, The University of Texas at Austin, Austin, TX 78712-0360, USA.
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