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Burnham HV, Cizauskas HE, Barefield DY. Fine tuning contractility: atrial sarcomere function in health and disease. Am J Physiol Heart Circ Physiol 2024; 326:H568-H583. [PMID: 38156887 DOI: 10.1152/ajpheart.00252.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024]
Abstract
The molecular mechanisms of sarcomere proteins underlie the contractile function of the heart. Although our understanding of the sarcomere has grown tremendously, the focus has been on ventricular sarcomere isoforms due to the critical role of the ventricle in health and disease. However, atrial-specific or -enriched myofilament protein isoforms, as well as isoforms that become expressed in disease, provide insight into ways this complex molecular machine is fine-tuned. Here, we explore how atrial-enriched sarcomere protein composition modulates contractile function to fulfill the physiological requirements of atrial function. We review how atrial dysfunction negatively affects the ventricle and the many cardiovascular diseases that have atrial dysfunction as a comorbidity. We also cover the pathophysiology of mutations in atrial-enriched contractile proteins and how they can cause primary atrial myopathies. Finally, we explore what is known about contractile function in various forms of atrial fibrillation. The differences in atrial function in health and disease underscore the importance of better studying atrial contractility, especially as therapeutics currently in development to modulate cardiac contractility may have different effects on atrial sarcomere function.
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Affiliation(s)
- Hope V Burnham
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States
| | - Hannah E Cizauskas
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States
| | - David Y Barefield
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, United States
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Vue Z, Neikirk K, Vang L, Garza-Lopez E, Christensen TA, Shao J, Lam J, Beasley HK, Marshall AG, Crabtree A, Anudokem J, Rodriguez B, Kirk B, Bacevac S, Barongan T, Shao B, Stephens DC, Kabugi K, Koh HJ, Koh A, Evans CS, Taylor B, Reddy AK, Miller-Fleming T, Actkins KV, Zaganjor E, Daneshgar N, Murray SA, Mobley BC, Damo SM, Gaddy JA, Riggs B, Wanjalla C, Kirabo A, McReynolds M, Gomez JA, Phillips MA, Exil V, Dai DF, Hinton A. Three-dimensional mitochondria reconstructions of murine cardiac muscle changes in size across aging. Am J Physiol Heart Circ Physiol 2023; 325:H965-H982. [PMID: 37624101 PMCID: PMC10977873 DOI: 10.1152/ajpheart.00202.2023] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 07/26/2023] [Accepted: 08/12/2023] [Indexed: 08/26/2023]
Abstract
With sparse treatment options, cardiac disease remains a significant cause of death among humans. As a person ages, mitochondria breakdown and the heart becomes less efficient. Heart failure is linked to many mitochondria-associated processes, including endoplasmic reticulum stress, mitochondrial bioenergetics, insulin signaling, autophagy, and oxidative stress. The roles of key mitochondrial complexes that dictate the ultrastructure, such as the mitochondrial contact site and cristae organizing system (MICOS), in aging cardiac muscle are poorly understood. To better understand the cause of age-related alteration in mitochondrial structure in cardiac muscle, we used transmission electron microscopy (TEM) and serial block facing-scanning electron microscopy (SBF-SEM) to quantitatively analyze the three-dimensional (3-D) networks in cardiac muscle samples of male mice at aging intervals of 3 mo, 1 yr, and 2 yr. Here, we present the loss of cristae morphology, the inner folds of the mitochondria, across age. In conjunction with this, the three-dimensional (3-D) volume of mitochondria decreased. These findings mimicked observed phenotypes in murine cardiac fibroblasts with CRISPR/Cas9 knockout of Mitofilin, Chchd3, Chchd6 (some members of the MICOS complex), and Opa1, which showed poorer oxidative consumption rate and mitochondria with decreased mitochondrial length and volume. In combination, these data show the need to explore if loss of the MICOS complex in the heart may be involved in age-associated mitochondrial and cristae structural changes.NEW & NOTEWORTHY This article shows how mitochondria in murine cardiac changes, importantly elucidating age-related changes. It also is the first to show that the MICOS complex may play a role in outer membrane mitochondrial structure.
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Affiliation(s)
- Zer Vue
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Kit Neikirk
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Larry Vang
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Edgar Garza-Lopez
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States
| | - Trace A Christensen
- Microscopy and Cell Analysis Core Facility, Mayo Clinic, Rochester, Minnesota, United States
| | - Jianqiang Shao
- Central Microscopy Research Facility, University of Iowa, Iowa City, Iowa, United States
| | - Jacob Lam
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States
| | - Heather K Beasley
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Andrea G Marshall
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Amber Crabtree
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Josephs Anudokem
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Benjamin Rodriguez
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Benjamin Kirk
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States
| | - Serif Bacevac
- Department of Internal Medicine, University of Iowa, Iowa City, Iowa, United States
| | - Taylor Barongan
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Bryanna Shao
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Dominique C Stephens
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
- Department of Life and Physical Sciences, Fisk University, Nashville, Tennessee, United States
| | - Kinuthia Kabugi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Ho-Jin Koh
- Department of Biological Sciences, Tennessee State University, Nashville, Tennessee, United States
| | - Alice Koh
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Chantell S Evans
- Department of Cell Biology, Duke University School of Medicine, Durham, North Carolina, United States
| | - Brittany Taylor
- J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, Florida, United States
| | - Anilkumar K Reddy
- Department of Medicine, Baylor College of Medicine, Houston, Texas, United States
| | - Tyne Miller-Fleming
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States
| | - Ky'Era V Actkins
- Division of Genetic Medicine, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States
| | - Elma Zaganjor
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
| | - Nastaran Daneshgar
- Department of Pathology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States
| | - Sandra A Murray
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Bret C Mobley
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States
| | - Steven M Damo
- Department of Life and Physical Sciences, Fisk University, Nashville, Tennessee, United States
| | - Jennifer A Gaddy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States
- Tennessee Valley Healthcare Systems, United States Department of Veterans Affairs, Nashville, Tennessee, United States
| | - Blake Riggs
- Department of Biology at San Francisco State University, San Francisco, California, United States
| | - Celestine Wanjalla
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States
| | - Annet Kirabo
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States
| | - Melanie McReynolds
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, Pennsylvania, United States
| | - Jose A Gomez
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, United States
| | - Mark A Phillips
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States
| | - Vernat Exil
- Division of Cardiology, Department of Pediatrics, St. Louis University School of Medicine, St. Louis, Missouri, United States
- Department of Pediatrics, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States
| | - Dao-Fu Dai
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Antentor Hinton
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, Tennessee, United States
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Gerzen OP, Potoskueva IK, Permyakova YV, Grebenschchikova AV, Selezneva IS, Nikitina LV. SDS-PAGE for Myosin Heavy Chains: Fast and Furious. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022070109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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Single cardiomyocytes from papillary muscles show lower preload-dependent activation of force compared to cardiomyocytes from the left ventricular free wall. J Mol Cell Cardiol 2022; 166:127-136. [DOI: 10.1016/j.yjmcc.2022.02.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 02/05/2022] [Accepted: 02/22/2022] [Indexed: 01/21/2023]
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The Impact of Melatonin Supplementation and NLRP3 Inflammasome Deletion on Age-Accompanied Cardiac Damage. Antioxidants (Basel) 2021; 10:antiox10081269. [PMID: 34439517 PMCID: PMC8389221 DOI: 10.3390/antiox10081269] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 07/29/2021] [Accepted: 08/06/2021] [Indexed: 12/16/2022] Open
Abstract
To investigate the role of NLRP3 inflammasome in cardiac aging, we evaluate here morphological and ultrastructural age-related changes of cardiac muscles fibers in wild-type and NLRP3-knockout mice, as well as studying the beneficial effect of melatonin therapy. The results clarified the beginning of the cardiac sarcopenia at the age of 12 months, with hypertrophy of cardiac myocytes, increased expression of β-MHC, appearance of small necrotic fibers, decline of cadiomyocyte number, destruction of mitochondrial cristae, appearance of small-sized residual bodies, and increased apoptotic nuclei ratio. These changes were progressed in the cardiac myocytes of 24 old mice, accompanied by excessive collagen deposition, higher expressions of IL-1α, IL-6, and TNFα, complete mitochondrial vacuolation and damage, myofibrils disorganization, multivesicular bodies formation, and nuclear fragmentation. Interestingly, cardiac myocytes of NLRP3-/- mice showed less detectable age-related changes compared with WT mice. Oral melatonin therapy preserved the normal cardiomyocytes structure, restored cardiomyocytes number, and reduced β-MHC expression of cardiac hypertrophy. In addition, melatonin recovered mitochondrial architecture, reduced apoptosis and multivesicular bodies' formation, and decreased expressions of β-MHC, IL-1α, and IL-6. Fewer cardiac sarcopenic changes and highly remarkable protective effects of melatonin treatment detected in aged cardiomyocytes of NLRP3-/- mice compared with aged WT animals, confirming implication of the NLRP3 inflammasome in cardiac aging. Thus, NLRP3 suppression and melatonin therapy may be therapeutic approaches for age-related cardiac sarcopenia.
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Alpha and beta myosin isoforms and human atrial and ventricular contraction. Cell Mol Life Sci 2021; 78:7309-7337. [PMID: 34704115 PMCID: PMC8629898 DOI: 10.1007/s00018-021-03971-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 10/03/2021] [Accepted: 10/08/2021] [Indexed: 01/15/2023]
Abstract
Human atrial and ventricular contractions have distinct mechanical characteristics including speed of contraction, volume of blood delivered and the range of pressure generated. Notably, the ventricle expresses predominantly β-cardiac myosin while the atrium expresses mostly the α-isoform. In recent years exploration of the properties of pure α- & β-myosin isoforms have been possible in solution, in isolated myocytes and myofibrils. This allows us to consider the extent to which the atrial vs ventricular mechanical characteristics are defined by the myosin isoform expressed, and how the isoform properties are matched to their physiological roles. To do this we Outline the essential feature of atrial and ventricular contraction; Explore the molecular structural and functional characteristics of the two myosin isoforms; Describe the contractile behaviour of myocytes and myofibrils expressing a single myosin isoform; Finally we outline the outstanding problems in defining the differences between the atria and ventricles. This allowed us consider what features of contraction can and cannot be ascribed to the myosin isoforms present in the atria and ventricles.
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Boldt K, Joumaa V, MacDonald G, Rios JL, Herzog W. Cardiac ventricular muscle mechanical properties through the first year of life in Sprague-Dawley rats. Mech Ageing Dev 2020; 192:111359. [PMID: 32956701 DOI: 10.1016/j.mad.2020.111359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 08/20/2020] [Accepted: 09/14/2020] [Indexed: 10/23/2022]
Abstract
Advanced age has been shown to result in decreased compliance, shortening velocity, and calcium sensitivity of the heart muscle. Even though cardiac health has been studied extensively in elderly populations, relatively little is known about cardiac health and age for the first part of adulthood. The purpose of this study was to compare cardiac contractile properties across the first year of life in rats (between 17-53 weeks), corresponding to early to mid-adulthood. Hearts were harvested from rats aged 17-, 24-, 36-, and 53-weeks. Skinned cardiac trabecular fibre bundle testing was used to evaluate active and passive force properties, maximum shortening velocity, calcium sensitivity, and myosin heavy chain isoforms. Maximum active stress production was not different between age groups. Calcium sensitivity increased progressively, while shortening velocity remained unchanged after an increase from 17-and 24-weeks. Passive stiffness decreased between 17- and 24-weeks, but then increased progressively through to 53-weeks. Thus, many of the observed detrimental changes in systolic function (reduced shortening velocity and calcium sensitivity) associated with aging, do not seem to occur in early to mid-adulthood, while early signs of increased diastolic stiffness manifest within 53 weeks of age and may represent a first sign of decreasing heart function and health.
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Affiliation(s)
- Kevin Boldt
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.
| | - Venus Joumaa
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Graham MacDonald
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Jaqueline Lourdes Rios
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Walter Herzog
- Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada; Biomechanics Laboratory, School of Sports, Federal University of Santa Catarina, Florianopolis, SC, Brazil
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8
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In-silico human electro-mechanical ventricular modelling and simulation for drug-induced pro-arrhythmia and inotropic risk assessment. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 159:58-74. [PMID: 32710902 PMCID: PMC7848595 DOI: 10.1016/j.pbiomolbio.2020.06.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 06/08/2020] [Accepted: 06/28/2020] [Indexed: 12/28/2022]
Abstract
Human-based computational modelling and simulation are powerful tools to accelerate the mechanistic understanding of cardiac patho-physiology, and to develop and evaluate therapeutic interventions. The aim of this study is to calibrate and evaluate human ventricular electro-mechanical models for investigations on the effect of the electro-mechanical coupling and pharmacological action on human ventricular electrophysiology, calcium dynamics, and active contraction. The most recent models of human ventricular electrophysiology, excitation-contraction coupling, and active contraction were integrated, and the coupled models were calibrated using human experimental data. Simulations were then conducted using the coupled models to quantify the effects of electro-mechanical coupling and drug exposure on electrophysiology and force generation in virtual human ventricular cardiomyocytes and tissue. The resulting calibrated human electro-mechanical models yielded active tension, action potential, and calcium transient metrics that are in agreement with experiments for endocardial, epicardial, and mid-myocardial human samples. Simulation results correctly predicted the inotropic response of different multichannel action reference compounds and demonstrated that the electro-mechanical coupling improves the robustness of repolarisation under drug exposure compared to electrophysiology-only models. They also generated additional evidence to explain the partial mismatch between in-silico and in-vitro experiments on drug-induced electrophysiology changes. The human calibrated and evaluated modelling and simulation framework constructed in this study opens new avenues for future investigations into the complex interplay between the electrical and mechanical cardiac substrates, its modulation by pharmacological action, and its translation to tissue and organ models of cardiac patho-physiology.
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9
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Boldt K, Rios JL, Joumaa V, Herzog W. Mechanical function of cardiac fibre bundles is partly protected by exercise in response to diet-induced obesity in rats. Appl Physiol Nutr Metab 2020; 46:46-54. [PMID: 32598858 DOI: 10.1139/apnm-2020-0275] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Decrements in contractile function resulting from obesity are thought to be major reasons for the link between obesity and cardiovascular disease, while exercise has been shown to improve cardiac muscle contractile function. The purpose of this study was to evaluate cardiac contractile properties following obesity induction and the potential protective effect of exercise. Twelve-week-old rats (n = 30) were organized into either a chow diet or a high-fat, high-sucrose (HFHS) diet group. Following 12 weeks of obesity induction the HFHS group animals were stratified and grouped into sedentary (HFHS+Sed) and exercise (HFHS+Ex) groups for an additional 12 weeks. Following 24 weeks of diet intervention, with 12 weeks of aerobic exercise (25 m/min, 30 min/day, 5 days/week) for the HFHS+Ex group, skinned cardiac fibre bundle testing was used to evaluate cardiac contractile properties. Body fat and mass were significantly greater in the HFHS-fed animals compared with the chow controls (p < 0.043). Hearts from rats in the HFHS+Sed group had significantly greater mass (p < 0.03), significantly slower maximum shortening velocity (p = 0.001), and tended to have lower calcium sensitivity (p = 0.077) and a lower proportion of α-myosin heavy chain composition (p = 0.074) than the sedentary chow animals. However, 12 weeks of moderate aerobic exercise partially prevented these decrements in contractile properties. Novelty Cardiac muscle from animals exposed to an obesogenic diet for 24 weeks had impaired contractile properties compared with controls. Obesity-induced impairment of contractile properties of the heart were partially prevented by a 12-week aerobic exercise regime.
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Affiliation(s)
- Kevin Boldt
- Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada.,Human Performance Laboratory, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Jaqueline Lourdes Rios
- Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada.,Human Performance Laboratory, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Venus Joumaa
- Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada.,Human Performance Laboratory, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Walter Herzog
- Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada.,Human Performance Laboratory, University of Calgary, Calgary, AB T2N 1N4, Canada.,Biomechanics Laboratory, School of Sports, Federal University of Santa Catarina, SC 88040-900, Brazil
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Boldt K, MacDonald G, Joumaa V, Herzog W. Mechanical adaptations of skinned cardiac muscle in response to dietary-induced obesity during adolescence in rats. Appl Physiol Nutr Metab 2020; 45:893-901. [PMID: 32134688 DOI: 10.1139/apnm-2019-0726] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Childhood obesity is a major risk factor for heart disease during adulthood, independent of adulthood behaviours. Therefore, it seems that childhood obesity leads to partly irreversible decrements in cardiac function. Little is known about how obesity during maturation affects the mechanical properties of the heart. The purpose of this study was to evaluate contractile properties in developing hearts from animals with dietary-induced obesity (high-fat high-sucrose diet). We hypothesized that obesity induced during adolescence results in decrements in cardiac contractile function. Three-week-old rats (n = 16) were randomized into control (chow) or dietary-induced obesity (high-fat high-sucrose diet) groups. Following 14 weeks on the diet, skinned cardiac trabeculae fibre bundle testing was performed to evaluate active and passive force, maximum shortening velocity, and calcium sensitivity. Rats in the high-fat high-sucrose diet group had significantly larger body mass and total body fat percentage. There were no differences in maximal active or passive properties of hearts between groups. Hearts from the high-fat high-sucrose diet rats had significantly slower maximum shortening velocities and lower calcium sensitivity than controls. Decreased shortening velocity and calcium sensitivity in hearts of obese animals may constitute increased risk of cardiac disease in adulthood. Novelty Cardiac muscle from animals exposed to an obesogenic diet during development had lower shortening velocity and calcium sensitivity than those from animals fed a chow diet. These alterations in mechanical function may be a mechanism for the increased risk of cardiac disease observed in adulthood.
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Affiliation(s)
- Kevin Boldt
- Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada.,Human Performance Laboratory, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Graham MacDonald
- Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada.,Human Performance Laboratory, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Venus Joumaa
- Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada.,Human Performance Laboratory, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Walter Herzog
- Faculty of Kinesiology, University of Calgary, Calgary, AB T2N 1N4, Canada.,Human Performance Laboratory, University of Calgary, Calgary, AB T2N 1N4, Canada
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Reda SM, Gollapudi SK, Chandra M. Developmental increase in β-MHC enhances sarcomere length-dependent activation in the myocardium. J Gen Physiol 2019; 151:635-644. [PMID: 30602626 PMCID: PMC6504293 DOI: 10.1085/jgp.201812183] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 10/08/2018] [Accepted: 11/29/2018] [Indexed: 01/10/2023] Open
Abstract
The expression of β-myosin heavy chain (β-MHC) in the guinea pig heart increases during postnatal development. Reda et al. show that this increase in β-MHC enhances length-mediated increases in myofilament Ca2+ sensitivity and sarcomere length–dependent changes in contractile function. Shifts in myosin heavy chain (MHC) isoforms in cardiac myocytes have been shown to alter cardiac muscle function not only in healthy developing hearts but also in diseased hearts. In guinea pig hearts, there is a large age-dependent shift in MHC isoforms from 80% α-MHC/20% β-MHC at 3 wk to 14% α-MHC/86% β-MHC at 11 wk. Because kinetic differences in α- and β-MHC cross-bridges (XBs) are known to impart different cooperative effects on thin filaments, we hypothesize here that differences in α- and β-MHC expression in guinea pig cardiac muscle impact sarcomere length (SL)–dependent contractile function. We therefore measure steady state and dynamic contractile parameters in detergent-skinned cardiac muscle preparations isolated from the left ventricles of young (3 wk old) or adult (11 wk old) guinea pigs at two different SLs: short (1.9 µm) and long (2.3 µm). Our data show that SL-dependent effects on contractile parameters are augmented in adult guinea pig cardiac muscle preparations. Notably, the SL-mediated increase in myofilament Ca2+ sensitivity (ΔpCa50) is twofold greater in adult guinea pig muscle preparations (ΔpCa50 being 0.11 units in adult preparations but only 0.05 units in young preparations). Furthermore, adult guinea pig cardiac muscle preparations display greater SL-dependent changes than young muscle preparations in (1) the magnitude of length-mediated increase in the recruitment of new force-bearing XBs, (2) XB detachment rate, (3) XB strain-mediated effects on other force-bearing XBs, and (4) the rate constant of force redevelopment. Our findings suggest that increased β-MHC expression enhances length-dependent activation in the adult guinea pig cardiac myocardium.
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Affiliation(s)
- Sherif M Reda
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA
| | - Sampath K Gollapudi
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA
| | - Murali Chandra
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, WA
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Rattanasopa C, Kirk JA, Bupha-Intr T, Papadaki M, de Tombe PP, Wattanapermpool J. Estrogen but not testosterone preserves myofilament function from doxorubicin-induced cardiotoxicity by reducing oxidative modifications. Am J Physiol Heart Circ Physiol 2019; 316:H360-H370. [PMID: 30499711 PMCID: PMC6397386 DOI: 10.1152/ajpheart.00428.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Here, we aimed to explore sex differences and the impact of sex hormones on cardiac contractile properties in doxorubicin (DOX)-induced cardiotoxicity. Male and female Sprague-Dawley rats were subjected to sham surgery or gonadectomy and then treated or untreated with DOX (2 mg/kg) every other week for 10 wk. Estrogen preserved maximum active tension (Tmax) with DOX exposure, whereas progesterone and testosterone did not. The effects of sex hormones and DOX correlated with both altered myosin heavy chain isoform expression and myofilament protein oxidation, suggesting both as possible mechanisms. However, acute treatment with oxidative stress (H2O2) or a reducing agent (DTT) indicated that the effects on Tmax were mediated by reversible myofilament oxidative modifications and not only changes in myosin heavy chain isoforms. There were also sex differences in the DOX impact on myofilament Ca2+ sensitivity. DOX increased Ca2+ sensitivity in male rats only in the absence of testosterone and in female rats only in the presence of estrogen. Conversely, DOX decreased Ca2+ sensitivity in female rats in the absence of estrogen. In most instances, this mechanism was through altered phosphorylation of troponin I at Ser23/Ser24. However, there was an additional DOX-induced, estrogen-dependent, irreversible (by DTT) mechanism that altered Ca2+ sensitivity. Our data demonstrate sex differences in cardiac contractile responses to chronic DOX treatment. We conclude that estrogen protects against chronic DOX treatment in the heart, preserving myofilament function. NEW & NOTEWORTHY We identified sex differences in cardiotoxic effects of chronic doxorubicin (DOX) exposure on myofilament function. Estrogen, but not testosterone, decreases DOX-induced oxidative modifications on myofilaments to preserve maximum active tension. In rats, DOX exposure increased Ca2+ sensitivity in the presence of estrogen but decreased Ca2+ sensitivity in the absence of estrogen. In male rats, the DOX-induced shift in Ca2+ sensitivity involved troponin I phosphorylation; in female rats, this was through an estrogen-dependent mechanism.
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Affiliation(s)
- Chutima Rattanasopa
- 1Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Jonathan A. Kirk
- 2Department of Cell and Molecular Physiology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois
| | - Tepmanas Bupha-Intr
- 1Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Maria Papadaki
- 2Department of Cell and Molecular Physiology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois
| | - Pieter P. de Tombe
- 2Department of Cell and Molecular Physiology, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois
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Pinzauti F, Pertici I, Reconditi M, Narayanan T, Stienen GJM, Piazzesi G, Lombardi V, Linari M, Caremani M. The force and stiffness of myosin motors in the isometric twitch of a cardiac trabecula and the effect of the extracellular calcium concentration. J Physiol 2018; 596:2581-2596. [PMID: 29714038 PMCID: PMC6023834 DOI: 10.1113/jp275579] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 04/13/2018] [Indexed: 01/22/2023] Open
Abstract
KEY POINTS Fast sarcomere-level mechanics in intact trabeculae, which allows the definition of the mechano-kinetic properties of cardiac myosin in situ, is a fundamental tool not only for understanding the molecular mechanisms of heart performance and regulation, but also for investigating the mechanisms of the cardiomyopathy-causing mutations in the myosin and testing small molecules for therapeutic interventions. The approach has been applied to measure the stiffness and force of the myosin motor and the fraction of motors attached during isometric twitches of electrically paced trabeculae under different extracellular Ca2+ concentrations. Although the average force of the cardiac myosin motor (∼6 pN) is similar to that of the fast myosin isoform of skeletal muscle, the stiffness (1.07 pN nm-1 ) is 2- to 3-fold smaller. The increase in the twitch force developed in the presence of larger extracellular Ca2+ concentrations is fully accounted for by a proportional increase in the number of attached motors. ABSTRACT The mechano-kinetic properties of the cardiac myosin were studied in situ, in trabeculae dissected from the right ventricle of the rat heart, by measuring the stiffness of the half-sarcomere both at the twitch force peak (Tp ) of an electrically paced intact trabecula at different extracellular Ca2+ concentrations ([Ca2+ ]o ), and in the same trabecula after skinning and induction of rigor. Taking into account the contribution of filament compliance to half-sarcomere compliance and the lattice geometry, we found that the stiffness of the cardiac myosin motor is 1.07 ± 0.09 pN nm-1 , which is slightly larger than that of the slow myosin isoform of skeletal muscle (0.6-0.8 pN nm-1 ) and 2- to 3-fold smaller than that of the fast skeletal muscle isoform. The increase in Tp from 61 ± 4 kPa to 93 ± 9 kPa, induced by raising [Ca2+ ]o from 1 to 2.5 mm at sarcomere length ∼2.2 μm, is accompanied by an increase of the half-sarcomere stiffness that is explained by an increase of the fraction of actin-attached motors from 0.08 ± 0.01 to 0.12 ± 0.02, proportional to Tp . Consequently, each myosin motor bears an average force of 6.14 ± 0.52 pN independently of Tp and [Ca2+ ]o . The application of fast sarcomere-level mechanics to intact trabeculae to define the mechano-kinetic properties of the cardiac myosin in situ represents a powerful tool for investigating cardiomyopathy-causing mutations in the myosin motor and testing specific therapeutic interventions.
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Affiliation(s)
| | | | | | | | - Ger J. M. Stienen
- Department of PhysiologyVU University Medical CenterAmsterdamThe Netherlands
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Martín-Fernández B, Gredilla R. Mitochondrial oxidative stress and cardiac ageing. CLINICA E INVESTIGACION EN ARTERIOSCLEROSIS 2018; 30:74-83. [PMID: 29398015 DOI: 10.1016/j.arteri.2017.12.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 12/11/2017] [Accepted: 12/14/2017] [Indexed: 10/18/2022]
Abstract
According with different international organizations, cardiovascular diseases are becoming the first cause of death in western countries. Although exposure to different risk factors, particularly those related to lifestyle, contribute to the etiopathogenesis of cardiac disorders, the increase in average lifespan and aging are considered major determinants of cardiac diseases events. Mitochondria and oxidative stress have been pointed out as relevant factors both in heart aging and in the development of cardiac diseases such as heart failure, cardiac hypertrophy and diabetic cardiomyopathy. During aging, cellular processes related with mitochondrial function, such as bioenergetics, apoptosis and inflammation are altered leading to cardiac dysfunction. Increasing our knowledge about the mitochondrial mechanisms related with the aging process, will provide new strategies in order to improve this process, particularly the cardiovascular ones.
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Affiliation(s)
- Beatriz Martín-Fernández
- Departamento de Fisiología, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, España.
| | - Ricardo Gredilla
- Departamento de Fisiología, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, España
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15
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Silva SD, Jara ZP, Peres R, Lima LS, Scavone C, Montezano AC, Touyz RM, Casarini DE, Michelini LC. Temporal changes in cardiac oxidative stress, inflammation and remodeling induced by exercise in hypertension: Role for local angiotensin II reduction. PLoS One 2017; 12:e0189535. [PMID: 29232407 PMCID: PMC5726656 DOI: 10.1371/journal.pone.0189535] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 11/27/2017] [Indexed: 12/15/2022] Open
Abstract
Exercise training reduces renin-angiotensin system (RAS) activation, decreases plasma and tissue oxidative stress and inflammation in hypertension. However, the temporal nature of these phenomena in response to exercise is unknown. We sought to determine in spontaneously hypertensive rats (SHR) and age-matched WKY controls the weekly effects of training on blood pressure (BP), plasma and left ventricle (LV) Ang II and Ang-(1–7) content (HPLC), LV oxidative stress (DHE staining), gene and protein expression (qPCR and WB) of pro-inflammatory cytokines, antioxidant enzymes and their consequence on hypertension-induced cardiac remodeling. SHR and WKY were submitted to aerobic training (T) or maintained sedentary (S) for 8 weeks; measurements were made at weeks 0, 1, 2, 4 and 8. Hypertension-induced cardiac hypertrophy was accompanied by acute plasma Ang II increase with amplified responses during the late phase of LV hypertrophy. Similar pattern was observed for oxidative stress markers, TNF alpha and interleukin-1β, associated with cardiomyocytes’ diameter enlargement and collagen deposition. SHR-T exhibited prompt and marked decrease in LV Ang II content (T1vs T4 in WKY-T), normalized oxidative stress (T2), augmented antioxidant defense (T4) and reduced both collagen deposition and inflammatory profile (T8), without changing cardiomyocytes’ diameter and LV hypertrophy. These changes were accompanied by decreased plasma Ang II content (T2-T4) and reduced BP (T8). SHR-T and WKY-T showed parallel increases in LV and plasma Ang-(1–7) content. Our data indicate that early training-induced downregulation of LV ACE-AngII-AT1 receptor axis is a crucial mechanism to reduce oxidative/pro-inflammatory profile and improve antioxidant defense in SHR-T, showing in addition this effect precedes plasma RAS deactivation.
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Affiliation(s)
- Sebastião D. Silva
- Department of Physiology & Biophysics, Biomedical Sciences Institute, University of Sao Paulo, Sao Paulo, SP, Brazil
- Institute of Cardiovascular and Medical Sciences, BHF GCRC, University of Glasgow, Glasgow, United Kingdom
| | - Zaira P. Jara
- Department of Medicine, Federal University of Sao Paulo, Sao Paulo, SP, Brazil
| | - Roseli Peres
- Department of Medicine, Federal University of Sao Paulo, Sao Paulo, SP, Brazil
| | - Larissa S. Lima
- Department of Pharmacology, Biomedical Sciences Institute, University of Sao Paulo, Sao Paulo, SP, Brazil
| | - Cristóforo Scavone
- Department of Pharmacology, Biomedical Sciences Institute, University of Sao Paulo, Sao Paulo, SP, Brazil
| | - Augusto C. Montezano
- Institute of Cardiovascular and Medical Sciences, BHF GCRC, University of Glasgow, Glasgow, United Kingdom
| | - Rhian M. Touyz
- Institute of Cardiovascular and Medical Sciences, BHF GCRC, University of Glasgow, Glasgow, United Kingdom
| | - Dulce E. Casarini
- Department of Medicine, Federal University of Sao Paulo, Sao Paulo, SP, Brazil
| | - Lisete C. Michelini
- Department of Physiology & Biophysics, Biomedical Sciences Institute, University of Sao Paulo, Sao Paulo, SP, Brazil
- * E-mail:
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16
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Insulin-like growth factor-1 signaling in cardiac aging. Biochim Biophys Acta Mol Basis Dis 2017; 1864:1931-1938. [PMID: 28847512 DOI: 10.1016/j.bbadis.2017.08.029] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 08/22/2017] [Accepted: 08/23/2017] [Indexed: 12/31/2022]
Abstract
Cardiovascular disease (CVD) is the leading cause of death in most developed countries. Aging is associated with enhanced risk of CVD. Insulin-like growth factor-1 (IGF-1) binds to its cognate receptor, IGF-1 receptor (IGF-1R), and exerts pleiotropic effects on cell growth, differentiation, development, and tissue repair. Importantly, IGF-1/IGF-1R signaling is implicated in cardiac aging and longevity. Cardiac aging is an intrinsic process that results in cardiac dysfunction, accompanied by molecular and cellular changes. In this review, we summarize the current state of knowledge regarding the link between the IGF-1/IGF-1R system and cardiac aging. The biological effects of IGF-1R and insulin receptor will be discussed and compared. Furthermore, we describe data regarding how deletion of IGF-1R in cardiomyocytes of aged knockout mice may delay the development of senescence-associated myocardial pathologies. This article is part of a Special issue entitled Cardiac adaptations to obesity, diabetes and insulin resistance, edited by Professors Jan F.C. Glatz, Jason R.B. Dyck and Christine Des Rosiers.
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Sukumaran A, Chang J, Han M, Mintri S, Khaw BA, Kim J. Iron overload exacerbates age-associated cardiac hypertrophy in a mouse model of hemochromatosis. Sci Rep 2017; 7:5756. [PMID: 28720890 PMCID: PMC5516030 DOI: 10.1038/s41598-017-05810-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 06/02/2017] [Indexed: 12/12/2022] Open
Abstract
Cardiac damage associated with iron overload is the most common cause of morbidity and mortality in patients with hereditary hemochromatosis, but the precise mechanisms leading to disease progression are largely unexplored. Here we investigated the effects of iron overload and age on cardiac hypertrophy using 1-, 5- and 12-month old Hfe-deficient mice, an animal model of hemochromatosis in humans. Cardiac iron levels increased progressively with age, which was exacerbated in Hfe-deficient mice. The heart/body weight ratios were greater in Hfe-deficient mice at 5- and 12-month old, compared with their age-matched wild-type controls. Cardiac hypertrophy in 12-month old Hfe-deficient mice was consistent with decreased alpha myosin and increased beta myosin heavy chains, suggesting an alpha-to-beta conversion with age. This was accompanied by cardiac fibrosis and up-regulation of NFAT-c2, reflecting increased calcineurin/NFAT signaling in myocyte hypertrophy. Moreover, there was an age-dependent increase in the cardiac isoprostane levels in Hfe-deficient mice, indicating elevated oxidative stress. Also, rats fed high-iron diet demonstrated increased heart-to-body weight ratios, alpha myosin heavy chain and cardiac isoprostane levels, suggesting that iron overload promotes oxidative stress and cardiac hypertrophy. Our findings provide a molecular basis for the progression of age-dependent cardiac stress exacerbated by iron overload hemochromatosis.
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Affiliation(s)
- Abitha Sukumaran
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - JuOae Chang
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Murui Han
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Shrutika Mintri
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Ban-An Khaw
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Jonghan Kim
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA.
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18
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Martín-Fernández B, Gredilla R. Mitochondria and oxidative stress in heart aging. AGE (DORDRECHT, NETHERLANDS) 2016; 38:225-238. [PMID: 27449187 PMCID: PMC5061683 DOI: 10.1007/s11357-016-9933-y] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 07/12/2016] [Indexed: 05/06/2023]
Abstract
As average lifespan of humans increases in western countries, cardiac diseases become the first cause of death. Aging is among the most important risk factors that increase susceptibility for developing cardiovascular diseases. The heart has very aerobic metabolism, and is highly dependent on mitochondrial function, since mitochondria generate more than 90 % of the intracellular ATP consumed by cardiomyocytes. In the last few decades, several investigations have supported the relevance of mitochondria and oxidative stress both in heart aging and in the development of cardiac diseases such as heart failure, cardiac hypertrophy, and diabetic cardiomyopathy. In the current review, we compile different studies corroborating this role. Increased mitochondria DNA instability, impaired bioenergetic efficiency, enhanced apoptosis, and inflammation processes are some of the events related to mitochondria that occur in aging heart, leading to reduced cellular survival and cardiac dysfunction. Knowing the mitochondrial mechanisms involved in the aging process will provide a better understanding of them and allow finding approaches to more efficiently improve this process.
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Affiliation(s)
- Beatriz Martín-Fernández
- Department of Physiology, Faculty of Medicine, Complutense University, Plaza Ramon y Cajal s/n, 28040, Madrid, Spain.
| | - Ricardo Gredilla
- Department of Physiology, Faculty of Medicine, Complutense University, Plaza Ramon y Cajal s/n, 28040, Madrid, Spain.
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19
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Yin Z, Ren J, Guo W. Sarcomeric protein isoform transitions in cardiac muscle: a journey to heart failure. Biochim Biophys Acta Mol Basis Dis 2014; 1852:47-52. [PMID: 25446994 DOI: 10.1016/j.bbadis.2014.11.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 10/27/2014] [Accepted: 11/04/2014] [Indexed: 01/05/2023]
Abstract
Sarcomeric protein isoforms are mainly governed by alternative promoter-driven expression, distinct gene expression, gene mutation and alternative mRNA splicing. The transitions of sarcomeric proteins have been implicated to play a role in the onset and development of human heart failure. In this mini-review, we summarized isoform transitions of several most widely examined sarcomeric proteins including myosin, actin, troponin, tropomyosin, titin and myosin binding protein-C, and the consequence of these abnormal isoform transitions. Even though the isoform transitions of sarcomeric proteins have been described in individual sarcomeric protein reviews, no concise summary of these results has been presented previously. This review is intended to fill this gap and discuss possible future perspectives.
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Affiliation(s)
- Zhiyong Yin
- Animal Science, College of Agriculture and Natural Resources, University of WY, Laramie WY82071, USA; Department of Cardiology, Xi Jing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Jun Ren
- Center for Cardiovascular Research and Alternative Medicine, College of Health Science, University of WY, Laramie WY82071, USA
| | - Wei Guo
- Animal Science, College of Agriculture and Natural Resources, University of WY, Laramie WY82071, USA; Center for Cardiovascular Research and Alternative Medicine, College of Health Science, University of WY, Laramie WY82071, USA.
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20
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Oliveira-Junior SA, Martinez PF, Guizoni DM, Campos DHS, Fernandes T, Oliveira EM, Okoshi MP, Okoshi K, Padovani CR, Cicogna AC. AT1 receptor blockade attenuates insulin resistance and myocardial remodeling in rats with diet-induced obesity. PLoS One 2014; 9:e86447. [PMID: 24466104 PMCID: PMC3900554 DOI: 10.1371/journal.pone.0086447] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Accepted: 12/09/2013] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Although obesity has been associated with metabolic and cardiac disturbances, the carrier mechanisms for these responses are poorly understood. This study analyzed whether angiotensin II blockade attenuates metabolic and cardiovascular disorders in rats with diet-induced obesity. MATERIAL AND METHODS Wistar-Kyoto (n = 40) rats were subjected to control (C; 3.2 kcal/g) and hypercaloric diets (OB; 4.6 kcal/g) for 30 weeks. Subsequently, rats were distributed to four groups: C, CL, OB, and OBL. L groups received Losartan (30 mg/kg/day) for five weeks. After this period we performed in vivo glucose tolerance and insulin tolerance tests, and measured triacylglycerol, insulin, angiotensin-converting enzyme activity (ACE), and leptin levels. Cardiovascular analyzes included systolic blood pressure (SBP), echocardiography, myocardial morphometric study, myosin heavy chain composition, and measurements of myocardial protein levels of angiotensin, extracellular signal-regulated (ERK1/2), c-Jun amino-terminal kinases (JNK), insulin receptor subunit β (βIR), and phosphatidylinositol 3-kinase (PI3K) by Western Blot. RESULTS Glucose metabolism, insulin, lipid, and ACE activity disorders observed with obesity were minimized by Losartan. Moreover, obesity was associated with increased SBP, myocardial hypertrophy, interstitial fibrosis and improved systolic performance; these effects were also minimized with Losartan. On a molecular level, OB exhibited higher ERK, Tyr-phosphorylated βIR, and PI3K expression, and reduced myocardial angiotensin and JNK expression. ERK and JNK expression were regulated in the presence of Losartan, while angiotensin, Tyr-βRI, total and Tyr-phosphorylated PI3K expression were elevated in the OBL group. CONCLUSION Angiotensin II blockade with Losartan attenuates obesity-induced metabolic and cardiovascular changes.
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Affiliation(s)
- Silvio A. Oliveira-Junior
- Botucatu Medical School, São Paulo State University, Botucatu, Brazil
- School of Physiotherapy, Federal University of Mato Grosso do Sul, Campo Grande, Brazil
| | - Paula F. Martinez
- Botucatu Medical School, São Paulo State University, Botucatu, Brazil
- School of Physiotherapy, Federal University of Mato Grosso do Sul, Campo Grande, Brazil
| | | | | | - Tiago Fernandes
- School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Edilamar M. Oliveira
- School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Marina P. Okoshi
- Botucatu Medical School, São Paulo State University, Botucatu, Brazil
| | - Katashi Okoshi
- Botucatu Medical School, São Paulo State University, Botucatu, Brazil
| | - Carlos R. Padovani
- Botucatu Biosciences Institute, São Paulo State University, Botucatu, Brazil
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21
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Campbell SG, Haynes P, Kelsey Snapp W, Nava KE, Campbell KS. Altered ventricular torsion and transmural patterns of myocyte relaxation precede heart failure in aging F344 rats. Am J Physiol Heart Circ Physiol 2013; 305:H676-86. [PMID: 23792678 DOI: 10.1152/ajpheart.00797.2012] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to identify and explain changes in ventricular and cellular function that contribute to aging-associated cardiovascular disease in aging F344 rats. Three groups of female F344 rats, aged 6, 18, and 22 mo, were studied. Echocardiographic measurements in isoflurane-anesthetized animals showed an increase in peak left ventricular torsion between the 6- and the 18-mo-old groups that was partially reversed in the 22-mo-old animals (P < 0.05). Epicardial, midmyocardial, and endocardial myocytes were subsequently isolated from the left ventricles of each group of rats. Unloaded sarcomere shortening and Ca(2+) transients were then measured in these cells (n = >75 cells for each of the nine age-region groups). The decay time of the Ca(2+) transient and the time required for 50% length relaxation both increased with age but not uniformly across the three regions (P < 0.02). Further analysis revealed a significant shift in the transmural distribution of these properties between 18 and 22 mo of age, with the largest changes occurring in epicardial myocytes. Computational modeling suggested that these changes were due in part to slower Ca(2+) dissociation from troponin in aging epicardial myocytes. Subsequent biochemical assays revealed a >50% reduction in troponin I phosphoprotein content in 22-mo-old epicardium relative to the other regions. These data suggest that between 18 and 22 mo of age (before the onset of heart failure), F344 rats display epicardial-specific myofilament-level modifications that 1) break from the progression observed between 6 and 18 mo and 2) coincide with aberrant patterns of cardiac torsion.
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Affiliation(s)
- Stuart G Campbell
- Department of Physiology and the Center for Muscle Biology, University of Kentucky, Lexington, Kentucky
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22
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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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23
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Chung E, Diffee GM. Moderate intensity, but not high intensity, treadmill exercise training alters power output properties in myocardium from aged rats. J Gerontol A Biol Sci Med Sci 2012; 67:1178-87. [PMID: 22843668 PMCID: PMC3636676 DOI: 10.1093/gerona/gls146] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 05/15/2012] [Indexed: 11/14/2022] Open
Abstract
Aging is characterized by a progressive decline in cardiac function, but endurance exercise training has been shown to retard a number of deleterious effects of aging. However, underlying mechanisms by which exercise training improves age-related decrements in myocardial contractile function are not well understood. The purpose of this study was to determine the effects of exercise training on power output properties in permeablized (skinned) myocytes of old rats. Thirty-month-old rats were divided into sedentary control (C) and groups undergoing 11 weeks of treadmill exercise training at moderate intensity (MI) and at high intensity (HI). Peak power output normalized to maximal force was significantly increased in MI but not in HI compared to C with significant increases in atrial myosin light chain 1 in ventricle. These results suggest that MI exercise training is beneficial as a significant increase was seen in the ability of the myocardium to do work, but this effect was not seen with HI training.
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Affiliation(s)
- Eunhee Chung
- Balke Biodynamics Laboratory, Department of Kinesiology,University of Wisconsin-Madison, Madison, Wisconsin 53706-1121, USA
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Chung E, Diffee GM. Effect of aging on power output properties in rat skinned cardiac myocytes. J Gerontol A Biol Sci Med Sci 2011; 66:1267-73. [PMID: 21896503 PMCID: PMC3210961 DOI: 10.1093/gerona/glr150] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 07/26/2011] [Indexed: 11/12/2022] Open
Abstract
Aging is generally associated with a decline in several indices of cardiac function. The cellular mechanisms for this decline are not completely understood. The ability of the myocardium to perform external work (power output) is a critical aspect of ventricular function. The purpose of this study was to determine the effect of aging on loaded shortening and power output properties. We measured force-velocity properties in permeabilized (skinned) myocytes from the hearts of 9-, 24-, and 33-month-old male Fisher 344 × Brown Norway F1 hybrid rats (F344BN) during loaded contractions using a force-clamp technique. Power output was calculated by multiplying force and shortening velocity values. We found that peak power output normalized to maximal force was significantly decreased by 18% and 31% in myocytes from 24- and 33-month-old group, respectively, compared with 9-month group (p < .05). These results suggest that aging is associated with a significant decrease in the ability of the myocardium to do work.
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Affiliation(s)
- Eunhee Chung
- Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin—Madison
- Present address: Molecular, Cellular, and Developmental Biology, University of Colorado—Boulder, Boulder, Colorado
| | - Gary M. Diffee
- Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin—Madison
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Campbell SG, McCulloch AD. Multi-scale computational models of familial hypertrophic cardiomyopathy: genotype to phenotype. J R Soc Interface 2011; 8:1550-61. [PMID: 21831889 DOI: 10.1098/rsif.2011.0184] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Familial hypertrophic cardiomyopathy (FHC) is an inherited disorder affecting roughly one in 500 people. Its hallmark is abnormal thickening of the ventricular wall, leading to serious complications that include heart failure and sudden cardiac death. Treatment is complicated by variation in the severity, symptoms and risks for sudden death within the patient population. Nearly all of the genetic lesions associated with FHC occur in genes encoding sarcomeric proteins, indicating that defects in cardiac muscle contraction underlie the condition. Detailed biophysical data are increasingly available for computational analyses that could be used to predict heart phenotypes based on genotype. These models must integrate the dynamic processes occurring in cardiac cells with properties of myocardial tissue, heart geometry and haemodynamic load in order to predict strain and stress in the ventricular walls and overall pump function. Recent advances have increased the biophysical detail in these models at the myofilament level, which will allow properties of FHC-linked mutant proteins to be accurately represented in simulations of whole heart function. The short-term impact of these models will be detailed descriptions of contractile dysfunction and altered myocardial strain patterns at the earliest stages of the disease-predictions that could be validated in genetically modified animals. Long term, these multi-scale models have the potential to improve clinical management of FHC through genotype-based risk stratification and personalized therapy.
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Affiliation(s)
- Stuart G Campbell
- Department of Bioengineering, University of California San Diego, , 9500 Gilman Drive, La Jolla, CA 92093-0412, USA
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26
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Tellez JO, Mczewski M, Yanni J, Sutyagin P, Mackiewicz U, Atkinson A, Inada S, Beresewicz A, Billeter R, Dobrzynski H, Boyett MR. Ageing-dependent remodelling of ion channel and Ca2+ clock genes underlying sino-atrial node pacemaking. Exp Physiol 2011; 96:1163-78. [PMID: 21724736 DOI: 10.1113/expphysiol.2011.057752] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The function of the sino-atrial node (SAN), the pacemaker of the heart, is known to decline with age, resulting in pacemaker disease in the elderly. The aim of the study was to investigate the effects of ageing on the SAN by characterizing electrophysiological changes and determining whether changes in gene expression are involved. In young and old rats, SAN function was characterized in the anaesthetized animal, isolated heart and isolated right atrium using ECG and action potential recordings; gene expression was characterized using quantitative PCR. The SAN function declined with age as follows: the intrinsic heart rate declined by 18 ± 3%; the corrected SAN recovery time increased by 43 ± 13%; and the SAN action potential duration increased by 11 ± 3% (at 75% repolarization). Gene expression in the SAN changed considerably with age, e.g. there was an age-dependent decrease in the Ca(2+) clock gene, RYR2, and changes in many ion channels (e.g. increases in Na(v)1.5, Na(v)β1 and Ca(v)1.2 and decreases in K(v)1.5 and HCN1). In conclusion, with age, there are changes in the expression of ion channel and Ca(2+) clock genes in the SAN, and the changes may provide a partial explanation for the age-dependent decline in pacemaker function.
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Cazorla O, Lacampagne A. Regional variation in myofilament length-dependent activation. Pflugers Arch 2011; 462:15-28. [DOI: 10.1007/s00424-011-0933-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Revised: 02/01/2011] [Accepted: 02/03/2011] [Indexed: 12/17/2022]
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29
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MacDonald JR, Oellermann M, Rynbeck S, Chang G, Ruggiero K, Cooper GJS, Hickey AJR. Transmural differences in respiratory capacity across the rat left ventricle in health, aging, and streptozotocin-induced diabetes mellitus: evidence that mitochondrial dysfunction begins in the subepicardium. Am J Physiol Cell Physiol 2010; 300:C246-55. [PMID: 21084644 DOI: 10.1152/ajpcell.00294.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
In diabetic cardiomyopathy, ventricular dysfunction occurs in the absence of hypertension or atherosclerosis and is accompanied by altered myocardial substrate utilization and depressed mitochondrial respiration. It is not known if mitochondrial function differs across the left ventricular (LV) wall in diabetes. In the healthy heart, the inner subendocardial region demonstrates higher rates of blood flow, oxygen consumption, and ATP turnover compared with the outer subepicardial region, but published transmural respirometric measurements have not demonstrated differences. We aim to measure mitochondrial function in Wistar rat LV to determine the effects of age, streptozotocin-diabetes, and LV layer. High-resolution respirometry measured indexes of respiration in saponin-skinned fibers dissected from the LV subendocardium and subepicardium of 3-mo-old rats after 1 mo of streptozotocin-induced diabetes and 4-mo-old rats following 2 mo of diabetes. Heart rate and heartbeat duration were measured under isoflurane-anesthesia using a fetal-Doppler, and transmission electron microscopy was employed to observe ultrastructural differences. Heart rate decreased with age and diabetes, whereas heartbeat duration increased with diabetes. While there were no transmural respirational differences in young healthy rat hearts, both myocardial layers showed a respiratory depression with age (30-40%). In 1-mo diabetic rat hearts only subepicardial respiration was depressed, whereas after 2 mo diabetes, respiration in subendocardial and subepicardial layers was depressed and showed elevated leak (state 2) respiration. These data provide evidence that mitochondrial dysfunction is first detectable in the subepicardium of diabetic rat LV, whereas there are measureable changes in LV mitochondria after only 4 mo of aging.
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Affiliation(s)
- J R MacDonald
- University of Auckland, School of Biological Sciences, Private Bag 92019, Auckland Mail Centre, Auckland 1142, New Zealand
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Chen Y, Somji A, Yu X, Stelzer JE. Altered in vivo left ventricular torsion and principal strains in hypothyroid rats. Am J Physiol Heart Circ Physiol 2010; 299:H1577-87. [PMID: 20729398 DOI: 10.1152/ajpheart.00406.2010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The twisting and untwisting motions of the left ventricle (LV) lead to efficient ejection of blood during systole and filling of the ventricle during diastole. Global LV mechanical performance is dependent on the contractile properties of cardiac myocytes; however, it is not known how changes in contractile protein expression affect the pattern and timing of LV rotation. At the myofilament level, contractile performance is largely dependent on the isoforms of myosin heavy chain (MHC) that are expressed. Therefore, in this study, we used MRI to examine the in vivo mechanical consequences of altered MHC isoform expression by comparing the contractile properties of hypothyroid rats, which expressed only the slow β-MHC isoform, and euthyroid rats, which predominantly expressed the fast α-MHC isoform. Unloaded shortening velocity (V(o)) and apparent rate constants of force development (k(tr)) were measured in the skinned ventricular myocardium isolated from euthyroid and hypothyroid hearts. Increased expression of β-MHC reduced LV torsion and fiber strain and delayed the development of peak torsion and strain during systole. Depressed in vivo mechanical performance in hypothyroid rats was related to slowed cross-bridge performance, as indicated by significantly slower V(o) and k(tr), compared with euthyroid rats. Dobutamine infusion in hypothyroid hearts produced smaller increases in torsion and strain and aberrant transmural torsion patterns, suggesting that the myocardial response to β-adrenergic stress is compromised. Thus, increased expression of β-MHC alters the pattern and decreases the magnitude of LV rotation, contributing to reduced mechanical performance during systole, especially in conditions of increased workload.
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Affiliation(s)
- Yong Chen
- Department of Biomedical Engineering, School of Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA
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31
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Campbell KS. Short-range mechanical properties of skeletal and cardiac muscles. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 682:223-46. [PMID: 20824529 DOI: 10.1007/978-1-4419-6366-6_13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Striated muscles are disproportionately stiff for small movements. This facet of their behavior can be demonstrated by measuring the force produced when the muscle is stretched more than about 1% of its initial length. When this is done, it can be seen that force rises rapidly during the initial phases of the movement and much less rapidly during the latter stages of the stretch. Experiments performed using chemically permeabilized skeletal and cardiac muscles show that the initial stiffness of the preparations increases in proportion with isometric force as the free Ca²(+) concentration in the bathing solution is raised from a minimal to a saturating value. This is strong evidence that the short-range mechanical properties of activated muscle result from stretching myosin cross-bridges that are attached between the thick and thin filaments. Relaxed intact muscles also exhibit short-range mechanical properties but the molecular mechanisms underlying this behavior are less clear. This chapter summarizes some of the interesting features of short-range mechanical properties in different types of muscle preparation, describes some of the likely underlying mechanisms and discusses the potential physiological significance of the behavior.
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Affiliation(s)
- Kenneth S Campbell
- Department of Physiology & Center for Muscle Biology, University of Kentucky, Lexington, KY 40503, USA.
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32
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Locher MR, Razumova MV, Stelzer JE, Norman HS, Patel JR, Moss RL. Determination of rate constants for turnover of myosin isoforms in rat myocardium: implications for in vivo contractile kinetics. Am J Physiol Heart Circ Physiol 2009; 297:H247-56. [PMID: 19395549 DOI: 10.1152/ajpheart.00922.2008] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ventricles of small mammals express mostly alpha-myosin heavy chain (alpha-MHC), a fast isoform, whereas the ventricles of large mammals, including humans, express approximately 10% alpha-MHC on a predominately beta-MHC (slow isoform) background. In failing human ventricles, the amount of alpha-MHC is dramatically reduced, leading to the hypothesis that even small amounts of alpha-MHC on a predominately beta-MHC background confer significantly higher rates of force development in healthy ventricles. To test this hypothesis, it is necessary to determine the fundamental rate constants of cross-bridge attachment (f(app)) and detachment (g(app)) for myosins composed of 100% alpha-MHC or beta-MHC, which can then be used to calculate twitch time courses for muscles expressing variable ratios of MHC isoforms. In the present study, rat skinned trabeculae expressing either 100% alpha-MHC or 100% beta-MHC were used to measure ATPase activity, isometric force, and the rate constant of force redevelopment (k(tr)) in solutions of varying Ca(2+) concentrations. The rate of ATP utilization was approximately 2.5-fold higher in preparations expressing 100% alpha-MHC compared with those expressing only beta-MHC, whereas k(tr) was 2-fold faster in the alpha-MHC myocardium. From these variables, we calculated f(app) to be approximately threefold higher for alpha-MHC than beta-MHC and g(app) to be twofold higher in alpha-MHC. Mathematical modeling of isometric twitches predicted that small increases in alpha-MHC significantly increased the rate of force development. These results suggest that low-level expression of alpha-MHC has significant effects on contraction kinetics.
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Affiliation(s)
- Matthew R Locher
- Department of Physiology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53711, USA.
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33
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Campbell SG, Howard E, Aguado-Sierra J, Coppola BA, Omens JH, Mulligan LJ, McCulloch AD, Kerckhoffs RCP. Effect of transmurally heterogeneous myocyte excitation-contraction coupling on canine left ventricular electromechanics. Exp Physiol 2009; 94:541-52. [PMID: 19251984 DOI: 10.1113/expphysiol.2008.044057] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The excitation-contraction coupling properties of cardiac myocytes isolated from different regions of the mammalian left ventricular wall have been shown to vary considerably, with uncertain effects on ventricular function. We embedded a cell-level excitation-contraction coupling model with region-dependent parameters within a simple finite element model of left ventricular geometry to study effects of electromechanical heterogeneity on local myocardial mechanics and global haemodynamics. This model was compared with one in which heterogeneous myocyte parameters were assigned randomly throughout the mesh while preserving the total amount of each cell subtype. The two models displayed nearly identical transmural patterns of fibre and cross-fibre strains at end-systole, but showed clear differences in fibre strains at earlier points during systole. Haemodynamic function, including peak left ventricular pressure, maximal rate of left ventricular pressure development and stroke volume, were essentially identical in the two models. These results suggest that in the intact ventricle heterogeneously distributed myocyte subtypes primarily impact local deformation of the myocardium, and that these effects are greatest during early systole.
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Affiliation(s)
- Stuart G Campbell
- Department of Bioengineering, University of California, San Diego, La Jolla, CA 92093-0412, USA
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34
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Davis J, Westfall MV, Townsend D, Blankinship M, Herron TJ, Guerrero-Serna G, Wang W, Devaney E, Metzger JM. Designing heart performance by gene transfer. Physiol Rev 2008; 88:1567-651. [PMID: 18923190 DOI: 10.1152/physrev.00039.2007] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The birth of molecular cardiology can be traced to the development and implementation of high-fidelity genetic approaches for manipulating the heart. Recombinant viral vector-based technology offers a highly effective approach to genetically engineer cardiac muscle in vitro and in vivo. This review highlights discoveries made in cardiac muscle physiology through the use of targeted viral-mediated genetic modification. Here the history of cardiac gene transfer technology and the strengths and limitations of viral and nonviral vectors for gene delivery are reviewed. A comprehensive account is given of the application of gene transfer technology for studying key cardiac muscle targets including Ca(2+) handling, the sarcomere, the cytoskeleton, and signaling molecules and their posttranslational modifications. The primary objective of this review is to provide a thorough analysis of gene transfer studies for understanding cardiac physiology in health and disease. By comparing results obtained from gene transfer with those obtained from transgenesis and biophysical and biochemical methodologies, this review provides a global view of cardiac structure-function with an eye towards future areas of research. The data presented here serve as a basis for discovery of new therapeutic targets for remediation of acquired and inherited cardiac diseases.
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Affiliation(s)
- Jennifer Davis
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
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Campbell SG, Flaim SN, Leem CH, McCulloch AD. Mechanisms of transmurally varying myocyte electromechanics in an integrated computational model. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2008; 366:3361-80. [PMID: 18593662 PMCID: PMC2556206 DOI: 10.1098/rsta.2008.0088] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The mechanical properties of myocardium vary across the transmural aspect of the left ventricular wall. Some of these functional heterogeneities may be related to differences in excitation-contraction coupling characteristics that have been observed in cells isolated from the epicardial, mid-myocardial and endocardial regions of the left ventricle of many species, including canine. Integrative models of coupled myocyte electromechanics are reviewed and used here to investigate sources of heterogeneous electromechanical behaviour in these cells. The simulations (i) illustrate a previously unrecognized role of the transient outward potassium current in mechanical function and (ii) suggest that there may also exist additional heterogeneities affecting crossbridge cycling rates in cells from different transmural regions.
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Affiliation(s)
- Stuart G. Campbell
- Department of Bioengineering, University of California, San Diego9500 Gilman Drive no. 0412, La Jolla, CA 92093, USA
| | - Sarah N. Flaim
- Computing Laboratory, University of OxfordWolfson Building, Parks Road, Oxford OX1 3QD, UK
| | - Chae H. Leem
- Department of Physiology, University of Ulsan College of Medicine388-1 Poongnap-Dong Songpa-Ku, Seoul 138-736, South Korea
| | - Andrew D. McCulloch
- Department of Bioengineering, University of California, San Diego9500 Gilman Drive no. 0412, La Jolla, CA 92093, USA
- Author for correspondence ()
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36
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Stelzer JE, Norman HS, Chen PP, Patel JR, Moss RL. Transmural variation in myosin heavy chain isoform expression modulates the timing of myocardial force generation in porcine left ventricle. J Physiol 2008; 586:5203-14. [PMID: 18787035 DOI: 10.1113/jphysiol.2008.160390] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Recent studies have shown that the sequence and timing of mechanical activation of myocardium vary across the ventricular wall. However, the contributions of variable expression of myofilament protein isoforms in mediating the timing of myocardial activation in ventricular systole are not well understood. To assess the functional consequences of transmural differences in myofilament protein expression, we studied the dynamic mechanical properties of multicellular skinned preparations isolated from the sub-endocardial and sub-epicardial regions of the porcine ventricular midwall. Compared to endocardial fibres, epicardial fibres exhibited significantly faster rates of stretch activation and force redevelopment (k(tr)), although the amount of force produced at a given [Ca2+] was not significantly different. Consistent with these results, SDS-PAGE analysis revealed significantly elevated expression of alpha myosin heavy chain (MHC) isoform in epicardial fibres (13 +/- 1%) versus endocardial fibres (3 +/- 1%). Linear regression analysis revealed that the apparent rates of delayed force development and force decay following stretch correlated with MHC isoform expression (r2 = 0.80 and r2 = 0.73, respectively, P < 0.05). No differences in the relative abundance or phosphorylation status of other myofilament proteins were detected. These data show that transmural differences in MHC isoform expression contribute to regional differences in dynamic mechanical function of porcine left ventricles, which in turn modulate the timing of force generation across the ventricular wall and work production during systole.
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Affiliation(s)
- Julian E Stelzer
- Department of Physiology, University of Wisconsin School of Medicine and Public Health, 601 Science Drive, Madison, WI 53711, USA.
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37
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Hankiewicz JH, Goldspink PH, Buttrick PM, Lewandowski ED. Principal strain changes precede ventricular wall thinning during transition to heart failure in a mouse model of dilated cardiomyopathy. Am J Physiol Heart Circ Physiol 2008; 294:H330-6. [DOI: 10.1152/ajpheart.01109.2007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study was performed to elucidate the relation between in vivo measurements of two-dimensional principal strains and the progression of left ventricle (LV) wall thinning during development of dilated cardiomyopathy in the protein kinase C-ε (PKC-ε) transgenic (TG) overexpressing mouse heart. Principal two-dimensional strains, E1 and E2, were determined in the LV wall of the anesthetized mouse using cardiac MRI tagging at 14.1 T. PKC-ε TG provided a model of pure dilated cardiomyopathy without evidence of hypertrophy (PKC-ε TG, n = 6). Ejection fraction, wall thickness, and principal strains were determined at 1-mo intervals in hearts of PKC-ε TG vs. age-matched, nontransgenic mice (NTG, n = 5) from age 6 to 13 mo. Through the study, PKC-ε TG displayed lower ejection fraction than NTG. At 7 mo, average principal strain E1 in PKC-ε TG hearts was lower compared with NTG (PKC-ε TG = 0.14 ± 0.03, NTG = 0.19 ± 0.03, P < 0.05). The greatest reductions in regional E1 occurred in the lateral segments. The principal strain E2 did not change significantly in either group. At 9 mo, LV wall thinning occurred in PKC-ε TG mice ( P < 0.01 vs. 8 mo) to 21% below values in NTG ( P < 0.001). Average E1 strain diverged between PKC-ε TG and NTG hearts by 25–43%. These E1 changes preceded LV wall thinning and predated the eventual transition from a compensated circumstance to the dilated phenotype. The findings indicate a near step function in E1 depression that precedes the onset of LV wall thinning and suggest E1 as a prognostic indicator of dilated cardiomyopathy.
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38
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Hamdani N, Kooij V, van Dijk S, Merkus D, Paulus WJ, Remedios CD, Duncker DJ, Stienen GJM, van der Velden J. Sarcomeric dysfunction in heart failure. Cardiovasc Res 2007; 77:649-58. [PMID: 18055579 DOI: 10.1093/cvr/cvm079] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Sarcomeric dysfunction plays a central role in reduced cardiac pump function in heart failure. This review focuses on the alterations in sarcomeric proteins in diseased myocardium that range from altered isoform expression to post-translational protein changes such as proteolysis and phosphorylation. Recent studies in animal models of heart failure and human failing myocardium converge and indicate that sarcomeric dysfunction, including altered maximum force development, Ca(2+) sensitivity, and increased passive stiffness, largely originates from altered protein phosphorylation, caused by neurohumoral-induced alterations in the kinase-phosphatase balance inside the cardiomyocytes. Novel therapies, which specifically target phosphorylation sites within sarcomeric proteins or the kinases and phosphatases involved, might improve cardiac function in heart failure.
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Affiliation(s)
- Nazha Hamdani
- Laboratory for Physiology, Institute for Cardiovascular Research, VU University Medical Center, van der Boechorststraat 7, Amsterdam, The Netherlands
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39
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Vida VL, Angelini A, Ausoni S, Bilardi A, Ori C, Vlassich F, Zoso V, Milanesi O, Sartore S, della Barbera M, Zaglia T, Thiene G, Stellin G. Age is a risk factor for maladaptive changes in rats exposed to increased pressure loading of the right ventricular myocardium. Cardiol Young 2007; 17:202-11. [PMID: 17381884 DOI: 10.1017/s1047951107000376] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 05/24/2006] [Indexed: 11/06/2022]
Abstract
OBJECTIVE To study the adaptive potential of the right ventricular myocardium after 30 days of mechanical-induced overload in rats from two different age groups. MATERIALS AND METHODS We banded the pulmonary trunk, so as to increase the systolic work load of the right ventricle, in 19 adult Sprague-Dawley rats at the age of 10 weeks, and 16 weanlings when they were 3 weeks-old, using 10 adults and 10 weanlings as controls. We analysed the functional adaptation and structural changes of the right ventricular myocardium, blood vessels and interstitial tissue after 30 days of increased afterload. RESULTS The increased workload induced an increase of the right ventricular weight and free wall thickness in animals from both age groups when compared to controls. These changes were mostly related to cardiomyocytic hypertrophy, as confirmed by the expression of myocardial hypertrophic markers, without any apparent increase of their number, a "reactive" fibrosis especially evident in the adult rats, with p-value less than 0.0001, and a more extensive neocapillary network in the weanlings compared to the adults aubsequent to banding, the p-value being less than 0.0001. CONCLUSION In response to right ventricular afterload, weanlings showed a higher adaptive capillary growth, which hampered the development of fibrosis as seen in the adult rats. Age seems to be a risk factor for adverse structural-functional changes of right ventricle subjected to increased workload.
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Affiliation(s)
- Vladimiro L Vida
- Department of Pediatric Cardiac Surgery, University of Padua, Padua, Italy.
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40
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Herron TJ, Vandenboom R, Fomicheva E, Mundada L, Edwards T, Metzger JM. Calcium-independent negative inotropy by beta-myosin heavy chain gene transfer in cardiac myocytes. Circ Res 2007; 100:1182-90. [PMID: 17363698 DOI: 10.1161/01.res.0000264102.00706.4e] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Increased relative expression of the slow molecular motor of the heart (beta-myosin heavy chain [MyHC]) is well known to occur in many rodent models of cardiovascular disease and in human heart failure. The direct effect of increased relative beta-MyHC expression on intact cardiac myocyte contractility, however, is unclear. To determine the direct effects of increased relative beta-MyHC expression on cardiac contractility, we used acute genetic engineering with a recombinant adenoviral vector (AdMYH7) to genetically titrate beta-MyHC protein expression in isolated rodent ventricular cardiac myocytes that predominantly expressed alpha-MyHC (fast molecular motor). AdMYH7-directed beta-MyHC protein expression and sarcomeric incorporation was observed as soon as 1 day after gene transfer. Effects of beta-MyHC expression on myocyte contractility were determined in electrically paced single myocytes (0.2 Hz, 37 degrees C) by measuring sarcomere shortening and intracellular calcium cycling. Gene transfer-based replacement of alpha-MyHC with beta-MyHC attenuated contractility in a dose-dependent manner, whereas calcium transients were unaffected. For example, when beta-MyHC expression accounted for approximately 18% of the total sarcomeric myosin, the amplitude of sarcomere-length shortening (nanometers, nm) was depressed by 42% (151.0+/-10.7 [control] versus 87.0+/-5.4 nm [AdMYH7 transduced]); and genetic titration of beta-MyHC, leading to 38% beta-MyHC content, attenuated shortening by 57% (138.9+/-13.0 versus 59.7+/-7.1 nm). Maximal isometric cross-bridge cycling rate was also slower in AdMYH7-transduced myocytes. Results indicate that small increases of beta-MyHC expression (18%) have Ca2+ transient-independent physiologically relevant effects to decrease intact cardiac myocyte function. We conclude that beta-MyHC is a negative inotrope among the cardiac myofilament proteins.
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Affiliation(s)
- Todd J Herron
- Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109-0622, USA.
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41
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Stelzer JE, Brickson SL, Locher MR, Moss RL. Role of myosin heavy chain composition in the stretch activation response of rat myocardium. J Physiol 2006; 579:161-73. [PMID: 17138609 PMCID: PMC2075383 DOI: 10.1113/jphysiol.2006.119719] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The speed and force of myocardial contraction during systolic ejection is largely dependent on the intrinsic contractile properties of cardiac myocytes. As the myosin heavy chain (MHC) isoform of cardiac muscle is an important determinant of the contractile properties of individual myocytes, we studied the effects of altered MHC isoform expression in rat myocardium on the mechanical properties of skinned ventricular preparations. Skinned myocardium from thyroidectomized rats expressing only the beta MHC isoform displayed rates of force redevelopment that were about 2.5-fold slower than in myocardium from hyperthyroid rats expressing only the alpha MHC isoform, but the amount of force generated at a given level of Ca2+ activation was not different. Because recent studies suggest that the stretch activation response in myocardium has an important role in systolic function, we also examined the effect of MHC isoform expression on the stretch activation response by applying a rapid stretch (1% of muscle length) to an otherwise isometrically contracting muscle fibre. Sudden stretch of myocardium resulted in a concomitant increase in force that quickly decayed to a minimum and was followed by a delayed redevelopment of force (i.e. stretch activation) to levels greater than prestretch force. beta MHC expression dramatically slowed the overall rate of the stretch activation response compared to expression of alpha MHC isoform; specifically, the rate of force decay was approximately 2-fold slower and the rate of delayed force development was approximately 2.5-fold slower. In contrast, MHC isoform had no effect on the amplitude of the stretch activation response. Collectively, these data show that expression of beta MHC in myocardium dramatically slows rates of cross-bridge recruitment and detachment which would be expected to decrease power output and contribute to depressed systolic function in end-stage heart failure.
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Affiliation(s)
- Julian E Stelzer
- Department of Physiology, University of Wisconsin Medical School, 601 Science Drive, Madison, WI 53711, USA.
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42
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Li SY, Yang X, Ceylan-Isik AF, Du M, Sreejayan N, Ren J. Cardiac contractile dysfunction in Lep/Lep obesity is accompanied by NADPH oxidase activation, oxidative modification of sarco(endo)plasmic reticulum Ca2+-ATPase and myosin heavy chain isozyme switch. Diabetologia 2006; 49:1434-46. [PMID: 16612592 DOI: 10.1007/s00125-006-0229-0] [Citation(s) in RCA: 134] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2005] [Accepted: 02/13/2006] [Indexed: 12/11/2022]
Abstract
AIMS/HYPOTHESIS Obesity is an independent risk factor for heart diseases but the underlying mechanism is not clear. This study examined cardiac contraction, oxidative stress, oxidative modification of sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) and the myosin heavy chain (MHC) isoform switch in obese mice. METHODS Mechanical properties were evaluated in ventricular myocytes from C57BL/6J lean and Lep/Lep obese mice (formerly known as ob/ob mice), including peak shortening (PS), time to 50 or 90% PS, time to 50 or 90% relengthening (TR50, TR90), maximal velocity of shortening/relengthening (+/-dL/dt), intracellular Ca2+ and its decay (tau). Oxidative stress, lipid peroxidation, protein damage and SERCA activity were assessed by glutathione/glutathione disulfide, malondialdehyde, protein carbonyl and 45Ca2+ uptake, respectively. NADPH oxidase was determined by immunoblotting. RESULTS Myocytes from Lep/Lep mice displayed depressed PS and +/- dL/dt, prolonged TR50, TR90, elevated resting [Ca2+]i, prolonged tau, reduced contractile capacity at high stimulus frequencies and diminished responsiveness to extracellular Ca2+ compared with lean controls. Cardiac glutathione/glutathione disulfide was decreased whereas malondialdehyde, protein carbonyl, membrane p47(phox) and membrane gp91(phox) were increased in the Lep/Lep group. SERCA isoenzyme 2a was markedly modified by oxidation in Lep/Lep hearts and associated with decreased 45Ca2+ uptake. The MHC isozyme displayed a shift from the alpha to the beta isoform in Lep/Lep hearts. Short-term incubation of angiotensin II with myocytes mimicked the mechanical defects, SERCA oxidation and 45Ca2+ uptake seen in Lep/Lep myocytes. Incubation of the NADPH oxidase inhibitor apocynin with Lep/Lep myocytes alleviated contractile defects without reversing SERCA oxidation or activity. CONCLUSIONS/INTERPRETATION These data indicate that obesity-related cardiac defects may be related to NADPH oxidase activation, oxidative damage to SERCA and the MHC isozyme switch.
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Affiliation(s)
- S-Y Li
- Division of Pharmaceutical Sciences and Center for Cardiovascular Research and Alternative Medicine, University of Wyoming, 1000 E. University Avenue, Laramie, WY 82071, USA
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