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Irving M. Functional control of myosin motors in the cardiac cycle. Nat Rev Cardiol 2024:10.1038/s41569-024-01063-5. [PMID: 39030271 DOI: 10.1038/s41569-024-01063-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/02/2024] [Indexed: 07/21/2024]
Abstract
Contraction of the heart is driven by cyclical interactions between myosin and actin filaments powered by ATP hydrolysis. The modular structure of heart muscle and the organ-level synchrony of the heartbeat ensure tight reciprocal coupling between this myosin ATPase cycle and the macroscopic cardiac cycle. The myosin motors respond to the cyclical activation of the actin and myosin filaments to drive the pressure changes that control the inflow and outflow valves of the heart chambers. Opening and closing of the valves in turn switches the myosin motors between roughly isometric and roughly isotonic contraction modes. Peak filament stress in the heart is much smaller than in fully activated skeletal muscle, although the myosin filaments in the two muscle types have the same number of myosin motors. Calculations indicate that only ~5% of the myosin motors in the heart are needed to generate peak systolic pressure, although many more motors are needed to drive ejection. Tight regulation of the number of active motors is essential for the efficient functioning of the healthy heart - this control is commonly disrupted by gene variants associated with inherited heart disease, and its restoration might be a useful end point in the development of novel therapies.
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Affiliation(s)
- Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics and BHF Centre for Research Excellence, King's College London, London, UK.
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2
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Abstract
Force generation in striated muscle is primarily controlled by structural changes in the actin-containing thin filaments triggered by an increase in intracellular calcium concentration. However, recent studies have elucidated a new class of regulatory mechanisms, based on the myosin-containing thick filament, that control the strength and speed of contraction by modulating the availability of myosin motors for the interaction with actin. This review summarizes the mechanisms of thin and thick filament activation that regulate the contractility of skeletal and cardiac muscle. A novel dual-filament paradigm of muscle regulation is emerging, in which the dynamics of force generation depends on the coordinated activation of thin and thick filaments. We highlight the interfilament signaling pathways based on titin and myosin-binding protein-C that couple thin and thick filament regulatory mechanisms. This dual-filament regulation mediates the length-dependent activation of cardiac muscle that underlies the control of the cardiac output in each heartbeat.
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Affiliation(s)
- Elisabetta Brunello
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom; ,
| | - Luca Fusi
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom; ,
- Centre for Human and Applied Physiological Sciences, School of Basic and Medical Biosciences, King's College London, London, United Kingdom
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3
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Sequeira V, Maack C, Reil GH, Reil JC. Exploring the Connection Between Relaxed Myosin States and the Anrep Effect. Circ Res 2024; 134:117-134. [PMID: 38175910 DOI: 10.1161/circresaha.123.323173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
The Anrep effect is an adaptive response that increases left ventricular contractility following an acute rise in afterload. Although the mechanistic origin remains undefined, recent findings suggest a two-phase activation of resting myosin for contraction, involving strain-sensitive and posttranslational phases. We propose that this mobilization represents a transition among the relaxed states of myosin-specifically, from the super-relaxed (SRX) to the disordered-relaxed (DRX)-with DRX myosin ready to participate in force generation. This hypothesis offers a unified explanation that connects myosin's SRX-DRX equilibrium and the Anrep effect as parts of a singular phenomenon. We underscore the significance of this equilibrium in modulating contractility, primarily studied in the context of hypertrophic cardiomyopathy, the most common inherited cardiomyopathy associated with diastolic dysfunction, hypercontractility, and left ventricular hypertrophy. As we posit that the cellular basis of the Anrep effect relies on a two-phased transition of myosin from the SRX to the contraction-ready DRX configuration, any dysregulation in this equilibrium may result in the pathological manifestation of the Anrep phenomenon. For instance, in hypertrophic cardiomyopathy, hypercontractility is linked to a considerable shift of myosin to the DRX state, implying a persistent activation of the Anrep effect. These valuable insights call for additional research to uncover a clinical Anrep fingerprint in pathological states. Here, we demonstrate through noninvasive echocardiographic pressure-volume measurements that this fingerprint is evident in 12 patients with hypertrophic obstructive cardiomyopathy before septal myocardial ablation. This unique signature is characterized by enhanced contractility, indicated by a leftward shift and steepening of the end-systolic pressure-volume relationship, and a prolonged systolic ejection time adjusted for heart rate, which reverses post-procedure. The clinical application of this concept has potential implications beyond hypertrophic cardiomyopathy, extending to other genetic cardiomyopathies and even noncongenital heart diseases with complex etiologies across a broad spectrum of left ventricular ejection fractions.
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Affiliation(s)
- Vasco Sequeira
- Department of Translational Science Universitätsklinikum, Deutsche Zentrum für Herzinsuffizienz (DZHI), Würzburg, Germany (V.S., C.M.)
| | - Christoph Maack
- Department of Translational Science Universitätsklinikum, Deutsche Zentrum für Herzinsuffizienz (DZHI), Würzburg, Germany (V.S., C.M.)
| | - Gert-Hinrich Reil
- Klinik für Kardiologie, Klinikum Oldenburg, Innere Medizin I, Germany (G.-H.R.)
| | - Jan-Christian Reil
- Klinik für Allgemeine und Interventionelle Kardiologie, Herz- und Diabetes-Zentrum Nordrhein-Westphalen, Germany (J.-C.R.)
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Balzi APDCC, Otsuki DA, Andrade L, Paiva W, Souza FL, Aureliano LGC, Malbouisson LMS. Can a Therapeutic Strategy for Hypotension Improve Cerebral Perfusion and Oxygenation in an Experimental Model of Hemorrhagic Shock and Severe Traumatic Brain Injury? Neurocrit Care 2023; 39:320-330. [PMID: 37535176 DOI: 10.1007/s12028-023-01802-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 07/03/2023] [Indexed: 08/04/2023]
Abstract
BACKGROUND Restoration of brain tissue perfusion is a determining factor in the neurological evolution of patients with traumatic brain injury (TBI) and hemorrhagic shock (HS). In a porcine model of HS without neurological damage, it was observed that the use of fluids or vasoactive drugs was effective in restoring brain perfusion; however, only terlipressin promoted restoration of cerebral oxygenation and lower expression of edema and apoptosis markers. It is unclear whether the use of vasopressor drugs is effective and beneficial during situations of TBI. The objective of this study is to compare the effects of resuscitation with saline solution and terlipressin on cerebral perfusion and oxygenation in a model of TBI and HS. METHODS Thirty-two pigs weighing 20-30 kg were randomly allocated into four groups: control (no treatment), saline (60 ml/kg of 0.9% NaCl), terlipressin (2 mg of terlipressin), and saline plus terlipressin (20 ml/kg of 0.9% NaCl + 2 mg of terlipressin). Brain injury was induced by lateral fluid percussion, and HS was induced through pressure-controlled bleeding, aiming at a mean arterial pressure (MAP) of 40 mmHg. After 30 min of circulatory shock, resuscitation strategies were initiated according to the group. The systemic and cerebral hemodynamic and oxygenation parameters, lactate levels, and hemoglobin levels were evaluated. The data were subjected to analysis of variance for repeated measures. The significance level established for statistical analysis was p < 0.05. RESULTS The terlipressin and saline plus terlipressin groups showed an increase in MAP that lasted until the end of the experiment (p < 0.05). There was a notable increase in intracranial pressure in all groups after starting treatment for shock. Cerebral perfusion pressure and cerebral oximetry showed no improvement after hemodynamic recovery in any group. The groups that received saline at resuscitation had the lowest hemoglobin concentrations after treatment. CONCLUSIONS The treatment of hypotension in HS with saline and/or terlipressin cannot restore cerebral perfusion or oxygenation in experimental models of HS and severe TBI. Elevated MAP raises intracranial pressure owing to brain autoregulation dysfunction caused by TBI.
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Affiliation(s)
- Ana Paula de Carvalho Canela Balzi
- Anesthesiology Department, Hospital das Clinicas SP, School of Medicine, University of São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 255, Cerqueira César, São Paulo, SP, 05403-000, Brazil.
- Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
- Divisão de Anestesia do ICHC, UTI Cirúrgica Pediátrica, Av. Enéas Carvalho de Aguiar, 255 - 8° Andar, Cerqueira César, São Paulo, SP, 05403-900, Brazil.
| | - Denise Aya Otsuki
- Medical Research Laboratory -LIM-08, Anesthesiology Department, School of Medicine, University of São Paulo, São Paulo, Brazil
- Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Lucia Andrade
- Nephrology Department, Hospital das Clinicas SP, School of Medicine, University of São Paulo, São Paulo, Brazil
- Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Wellingson Paiva
- Neurosurgery Department, Hospital das Clinicas SP, School of Medicine, University of São Paulo, São Paulo, Brazil
- Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Felipe Lima Souza
- Medical Research Laboratory, Nephrology Department, School of Medicine, University of São Paulo, São Paulo, Brazil
- Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Luiz Guilherme Cernaglia Aureliano
- Pathology Department, Hospital das Clinicas SP, School of Medicine, University of São Paulo, São Paulo, Brazil
- Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
| | - Luiz Marcelo Sá Malbouisson
- Anesthesiology Department, Hospital das Clinicas SP, School of Medicine, University of São Paulo, Av. Dr. Enéas de Carvalho Aguiar, 255, Cerqueira César, São Paulo, SP, 05403-000, Brazil
- Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil
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Morbach C, Simon I, Danner E, Gelbrich G, Stefenelli U, Sahiti F, Scholz N, Cejka V, Albert J, Ertl G, Angermann CE, Güder G, Frantz S, Heuschmann PU, Maack C, Störk S. Heart rate-corrected systolic ejection time: population-based reference values and differential prognostic utility in acute heart failure. EUROPEAN HEART JOURNAL. IMAGING METHODS AND PRACTICE 2023; 1:qyad020. [PMID: 39045077 PMCID: PMC11195710 DOI: 10.1093/ehjimp/qyad020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 08/12/2023] [Indexed: 07/25/2024]
Abstract
Aims Systolic ejection time (SET) is discussed as a treatment target in patients with heart failure (HF) and a reduced left ventricular (LV) ejection fraction (EF). We derived reference values for SET correcting for its dependence on heart rate (SETc), and explored its prognostic utility in patients admitted with decompensated HF. Methods and results SETc was derived in 4836 participants of the population-based STAAB study (mean age 55 ± 12 years, 52% women). There, mean SETc was 328 ± 18 ms, increased with age (+4.7 ms per decade), was shorter in men than women (-14.9 ms), and correlated with arterial elastance (r = 0.30; all P < 0.001). In 134 patients hospitalized with acute HF, SETc at admission was shorter when compared with the general population and differed between patients with HF with reduced EF (HFrEF; LVEF ≤40%; 269 ± 35 ms), HF with mildly reduced EF (HFmrEF; LVEF 41-49%; 294 ± 27 ms), and HF with preserved EF (HFpEF; LVEF ≥50%; 317 ± 35 ms; P < 0.001). In proportional hazard regression, an in-hospital increase in SETc was associated with an age- and sex-adjusted hazard ratio of 0.38 (95% confidence interval 0.18-0.79) in patients with HFrEF, but a hazard ratio of 2.39 (95% confidence interval 1.24-4.64) in patients with HFpEF. Conclusion In the general population, SETc increased with age and an elevated afterload. SETc was mildly reduced in patients hospitalized with HFpEF, but markedly reduced in patients with HFrEF. In-hospital prolongation of SETc predicted a favourable outcome in HFrEF, but an adverse outcome in HFpEF. Our results support the concept of a U-shaped relationship between cardiac systolic function and risk, providing a rationale for a more individualized treatment approach in patients with HF.
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Affiliation(s)
- Caroline Morbach
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
- Department Medicine I, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Isabelle Simon
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
| | - Elisabeth Danner
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
| | - Götz Gelbrich
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
- Institute of Clinical Epidemiology and Biometry, University Würzburg, Joseph-Schneider-Str. 2, 97080 Würzburg, Germany
- Clinical Trial Center, University Hospital Würzburg, Joseph-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Ulrich Stefenelli
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
| | - Floran Sahiti
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
- Department Medicine I, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Nina Scholz
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
| | - Vladimir Cejka
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
| | - Judith Albert
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
- Department Medicine I, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Georg Ertl
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
- Department Medicine I, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Christiane E Angermann
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
- Department Medicine I, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Gülmisal Güder
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
- Department Medicine I, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Stefan Frantz
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
- Department Medicine I, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Peter U Heuschmann
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
- Institute of Clinical Epidemiology and Biometry, University Würzburg, Joseph-Schneider-Str. 2, 97080 Würzburg, Germany
- Clinical Trial Center, University Hospital Würzburg, Joseph-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Christoph Maack
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
- Department Medicine I, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Stefan Störk
- Department Clinical Research and Epidemiology, Comprehensive Heart Failure Center, University Hospital Würzburg, Am Schwarzenberg 15, 97078 Würzburg, Germany
- Department Medicine I, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
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Nag S, Gollapudi SK, Del Rio CL, Spudich JA, McDowell R. Mavacamten, a precision medicine for hypertrophic cardiomyopathy: From a motor protein to patients. SCIENCE ADVANCES 2023; 9:eabo7622. [PMID: 37506209 DOI: 10.1126/sciadv.abo7622] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2022] [Accepted: 06/23/2023] [Indexed: 07/30/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) is a primary myocardial disorder characterized by left ventricular hypertrophy, hyperdynamic contraction, and impaired relaxation of the heart. These functional derangements arise directly from altered sarcomeric function due to either mutations in genes encoding sarcomere proteins, or other defects such as abnormal energetics. Current treatment options do not directly address this causal biology but focus on surgical and extra-sarcomeric (sarcolemmal) pharmacological symptomatic relief. Mavacamten (formerly known as MYK-461), is a small molecule designed to regulate cardiac function at the sarcomere level by selectively but reversibly inhibiting the enzymatic activity of myosin, the fundamental motor of the sarcomere. This review summarizes the mechanism and translational progress of mavacamten from proteins to patients, describing how the mechanism of action and pharmacological characteristics, involving both systolic and diastolic effects, can directly target pathophysiological derangements within the cardiac sarcomere to improve cardiac structure and function in HCM. Mavacamten was approved by the Food and Drug Administration in April 2022 for the treatment of obstructive HCM and now goes by the commercial name of Camzyos. Full information about the risks, limitations, and side effects can be found at www.accessdata.fda.gov/drugsatfda_docs/label/2022/214998s000lbl.pdf.
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Affiliation(s)
- Suman Nag
- MyoKardia Inc., a wholly owned subsidiary of Bristol Myers Squibb, Brisbane, CA 94005, USA
| | - Sampath K Gollapudi
- MyoKardia Inc., a wholly owned subsidiary of Bristol Myers Squibb, Brisbane, CA 94005, USA
| | - Carlos L Del Rio
- MyoKardia Inc., a wholly owned subsidiary of Bristol Myers Squibb, Brisbane, CA 94005, USA
- Cardiac Consulting, 1630 S Delaware St. #56426, San Mateo, CA 94403, USA
| | | | - Robert McDowell
- MyoKardia Inc., a wholly owned subsidiary of Bristol Myers Squibb, Brisbane, CA 94005, USA
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Marcucci L. Muscle Mechanics and Thick Filament Activation: An Emerging Two-Way Interaction for the Vertebrate Striated Muscle Fine Regulation. Int J Mol Sci 2023; 24:ijms24076265. [PMID: 37047237 PMCID: PMC10094676 DOI: 10.3390/ijms24076265] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 03/12/2023] [Accepted: 03/21/2023] [Indexed: 03/29/2023] Open
Abstract
Contraction in striated muscle is classically described as regulated by calcium-mediated structural changes in the actin-containing thin filaments, which release the binding sites for the interaction with myosin motors to produce force. In this view, myosin motors, arranged in the thick filaments, are basically always ready to interact with the thin filaments, which ultimately regulate the contraction. However, a new “dual-filament” activation paradigm is emerging, where both filaments must be activated to generate force. Growing evidence from the literature shows that the thick filament activation has a role on the striated muscle fine regulation, and its impairment is associated with severe pathologies. This review is focused on the proposed mechanical feedback that activates the inactive motors depending on the level of tension generated by the active ones, the so-called mechanosensing mechanism. Since the main muscle function is to generate mechanical work, the implications on muscle mechanics will be highlighted, showing: (i) how non-mechanical modulation of the thick filament activation influences the contraction, (ii) how the contraction influences the activation of the thick filament and (iii) how muscle, through the mechanical modulation of the thick filament activation, can regulate its own mechanics. This description highlights the crucial role of the emerging bi-directional feedback on muscle mechanical performance.
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Affiliation(s)
- Lorenzo Marcucci
- Department of Biomedical Sciences, University of Padova, 35131 Padova, Italy;
- Center for Biosystems Dynamics Research, RIKEN, Suita 565-0874, Japan
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Rupert C, López JE, Cortez-Toledo E, De la Cruz Cabrera O, Chesler NC, Simpson PC, Campbell SG, Baker AJ. Increased length-dependent activation of human engineered heart tissue after chronic α 1A-adrenergic agonist treatment: testing a novel heart failure therapy. Am J Physiol Heart Circ Physiol 2023; 324:H293-H304. [PMID: 36637971 PMCID: PMC9886349 DOI: 10.1152/ajpheart.00279.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 12/06/2022] [Accepted: 12/23/2022] [Indexed: 01/14/2023]
Abstract
Chronic stimulation of cardiac α1A-adrenergic receptors (α1A-ARs) improves symptoms in multiple preclinical models of heart failure. However, the translational significance remains unclear. Human engineered heart tissues (EHTs) provide a means of quantifying the effects of chronic α1A-AR stimulation on human cardiomyocyte physiology. EHTs were created from thin slices of decellularized pig myocardium seeded with human induced pluripotent stem cell (iPSC)-derived cardiomyocytes and fibroblasts. With a paired experimental design, EHTs were cultured for 3 wk, mechanically tested, cultured again for 2 wk with α1A-AR agonist A61603 (10 nM) or vehicle control, and retested after drug washout for 24 h. Separate control experiments determined the effects of EHT age (3-5 wk) or repeat mechanical testing. We found that chronic A61603 treatment caused a 25% increase of length-dependent activation (LDA) of contraction compared with vehicle treatment (n = 7/group, P = 0.035). EHT force was not increased after chronic A61603 treatment. However, after vehicle treatment, EHT force was increased by 35% relative to baseline testing (n = 7/group, P = 0.022), suggesting EHT maturation. Control experiments suggested that increased EHT force resulted from repeat mechanical testing, not from EHT aging. RNA-seq analysis confirmed that the α1A-AR is expressed in human EHTs and found chronic A61603 treatment affected gene expression in biological pathways known to be activated by α1A-ARs, including the MAP kinase signaling pathway. In conclusion, increased LDA in human EHT after chronic A61603 treatment raises the possibility that chronic stimulation of the α1A-AR might be beneficial for increasing LDA in human myocardium and might be beneficial for treating human heart failure by restoring LDA.NEW & NOTEWORTHY Chronic stimulation of α1A-adrenergic receptors (α1A-ARs) is known to mediate therapeutic effects in animal heart failure models. To investigate the effects of chronic α1A-AR stimulation in human cardiomyocytes, we tested engineered heart tissue (EHT) created with iPSC-derived cardiomyocytes. RNA-seq analysis confirmed human EHT expressed α1A-ARs. Chronic (2 wk) α1A-AR stimulation with A61603 (10 nM) increased length-dependent activation (LDA) of contraction. Chronic α1A-AR stimulation might be beneficial for treating human heart failure by restoring LDA.
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Affiliation(s)
- C. Rupert
- Propria LLC, Branford, Connecticut, United States
| | - J. E. López
- Division of Cardiovascular Medicine, Department of Internal Medicine,
University of California Davis, Davis, California, United States
| | - E. Cortez-Toledo
- Division of Cardiovascular Medicine, Department of Internal Medicine,
University of California Davis, Davis, California, United States
| | | | - N. C. Chesler
- Edwards Lifesciences Foundation Cardiovascular Innovation Research Center, Irvine, California, United States
- Department of Biomedical Engineering, University of California, Irvine, California, United States
| | - P. C. Simpson
- Cardiology Division, Veterans Affairs Medical Center, San Francisco, California, United States
- Department of Medicine, University of California, San Francisco, California, United States
| | - S. G. Campbell
- Departments of Biomedical Engineering and Cellular and Molecular Physiology, Yale University, New Haven, Connecticut, United States
| | - A. J. Baker
- Cardiology Division, Veterans Affairs Medical Center, San Francisco, California, United States
- Department of Medicine, University of California, San Francisco, California, United States
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9
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Sevrieva IR, Ponnam S, Yan Z, Irving M, Kampourakis T, Sun YB. Phosphorylation-dependent interactions of myosin-binding protein C and troponin coordinate the myofilament response to protein kinase A. J Biol Chem 2023; 299:102767. [PMID: 36470422 PMCID: PMC9826837 DOI: 10.1016/j.jbc.2022.102767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 11/23/2022] [Accepted: 11/24/2022] [Indexed: 12/12/2022] Open
Abstract
PKA-mediated phosphorylation of sarcomeric proteins enhances heart muscle performance in response to β-adrenergic stimulation and is associated with accelerated relaxation and increased cardiac output for a given preload. At the cellular level, the latter translates to a greater dependence of Ca2+ sensitivity and maximum force on sarcomere length (SL), that is, enhanced length-dependent activation. However, the mechanisms by which PKA phosphorylation of the most notable sarcomeric PKA targets, troponin I (cTnI) and myosin-binding protein C (cMyBP-C), lead to these effects remain elusive. Here, we specifically altered the phosphorylation level of cTnI in heart muscle cells and characterized the structural and functional effects at different levels of background phosphorylation of cMyBP-C and with two different SLs. We found Ser22/23 bisphosphorylation of cTnI was indispensable for the enhancement of length-dependent activation by PKA, as was cMyBP-C phosphorylation. This high level of coordination between cTnI and cMyBP-C may suggest coupling between their regulatory mechanisms. Further evidence for this was provided by our finding that cardiac troponin (cTn) can directly interact with cMyBP-C in vitro, in a phosphorylation- and Ca2+-dependent manner. In addition, bisphosphorylation at Ser22/Ser23 increased Ca2+ sensitivity at long SL in the presence of endogenously phosphorylated cMyBP-C. When cMyBP-C was dephosphorylated, bisphosphorylation of cTnI increased Ca2+ sensitivity and decreased cooperativity at both SLs, which may translate to deleterious effects in physiological settings. Our results could have clinical relevance for disease pathways, where PKA phosphorylation of cTnI may be functionally uncoupled from cMyBP-C phosphorylation due to mutations or haploinsufficiency.
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Affiliation(s)
- Ivanka R Sevrieva
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom.
| | - Saraswathi Ponnam
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Ziqian Yan
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Malcolm Irving
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
| | - Yin-Biao Sun
- Randall Centre for Cell and Molecular Biophysics, and British Heart Foundation Centre of Research Excellence, King's College London, London, United Kingdom
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10
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Han J, Taberner AJ, Loiselle DS, Tran K. Cardiac efficiency and Starling's Law of the Heart. J Physiol 2022; 600:4265-4285. [PMID: 35998082 PMCID: PMC9826111 DOI: 10.1113/jp283632] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 08/18/2022] [Indexed: 01/11/2023] Open
Abstract
The formulation by Starling of The Law of the Heart states that 'the [mechanical] energy of contraction, however measured, is a function of the length of the muscle fibre'. Starling later also stated that 'the oxygen consumption of the isolated heart … is determined by its diastolic volume, and therefore by the initial length of its muscular fibres'. This phrasing has motivated us to extend Starling's Law of the Heart to include consideration of the efficiency of contraction. In this study, we assessed both mechanical efficiency and crossbridge efficiency by studying the heat output of isolated rat ventricular trabeculae performing force-length work-loops over ranges of preload and afterload. The combination of preload and afterload allowed us, using our modelling frameworks for the end-systolic zone and the heat-force zone, to simulate cases by recreating physiologically feasible loading conditions. We found that across all cases examined, both work output and change of enthalpy increased with initial muscle length; hence it can only be that the former increases more than the latter to yield increased mechanical efficiency. In contrast, crossbridge efficiency increased with initial muscle length in cases where the extent of muscle shortening varied greatly with preload. We conclude that the efficiency of cardiac contraction increases with increasing initial muscle length and preload. An implication of our conclusion is that the length-dependent activation mechanism underlying the cellular basis of Starling's Law of the Heart is an energetically favourable process that increases the efficiency of cardiac contraction. KEY POINTS: Ernest Starling in 1914 formulated the Law of the Heart to describe the mechanical property of cardiac muscle whereby force of contraction increases with muscle length. He subsequently, in 1927, showed that the oxygen consumption of the heart is also a function of the length of the muscle fibre, but left the field unclear as to whether cardiac efficiency follows the same dependence. A century later, the field has gained an improved understanding of the factors, including the distinct effects of preload and afterload, that affect cardiac efficiency. This understanding presents an opportunity for us to investigate the elusive length-dependence of cardiac efficiency. We found that, by simulating physiologically feasible loading conditions using a mechano-energetics framework, cardiac efficiency increased with initial muscle length. A broader physiological importance of our findings is that the underlying cellular basis of Starling's Law of the Heart is an energetically favourable process that yields increased efficiency.
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Affiliation(s)
- June‐Chiew Han
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand
| | - Andrew J. Taberner
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand,Department of Engineering ScienceUniversity of AucklandAucklandNew Zealand
| | - Denis S. Loiselle
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand,Department of PhysiologyUniversity of AucklandAucklandNew Zealand
| | - Kenneth Tran
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand
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11
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Solís C, Russell B. Striated muscle proteins are regulated both by mechanical deformation and by chemical post-translational modification. Biophys Rev 2021; 13:679-695. [PMID: 34777614 DOI: 10.1007/s12551-021-00835-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 08/23/2021] [Indexed: 01/09/2023] Open
Abstract
All cells sense force and build their cytoskeleton to optimize function. How is this achieved? Two major systems are involved. The first is that load deforms specific protein structures in a proportional and orientation-dependent manner. The second is post-translational modification of proteins as a consequence of signaling pathway activation. These two processes work together in a complex way so that local subcellular assembly as well as overall cell function are controlled. This review discusses many cell types but focuses on striated muscle. Detailed information is provided on how load deforms the structure of proteins in the focal adhesions and filaments, using α-actinin, vinculin, talin, focal adhesion kinase, LIM domain-containing proteins, filamin, myosin, titin, and telethonin as examples. Second messenger signals arising from external triggers are distributed throughout the cell causing post-translational or chemical modifications of protein structures, with the actin capping protein CapZ and troponin as examples. There are numerous unanswered questions of how mechanical and chemical signals are integrated by muscle proteins to regulate sarcomere structure and function yet to be studied. Therefore, more research is needed to see how external triggers are integrated with local tension generated within the cell. Nonetheless, maintenance of tension in the sarcomere is the essential and dominant mechanism, leading to the well-known phrase in exercise physiology: "use it or lose it."
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Affiliation(s)
- Christopher Solís
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612 USA
| | - Brenda Russell
- Department of Physiology and Biophysics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60612 USA
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12
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Loescher CM, Hobbach AJ, Linke WA. Titin (TTN): from molecule to modifications, mechanics and medical significance. Cardiovasc Res 2021; 118:2903-2918. [PMID: 34662387 PMCID: PMC9648829 DOI: 10.1093/cvr/cvab328] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 10/13/2021] [Indexed: 12/19/2022] Open
Abstract
The giant sarcomere protein titin is a major determinant of cardiomyocyte stiffness and contributor to cardiac strain sensing. Titin-based forces are highly regulated in health and disease, which aids in the regulation of myocardial function, including cardiac filling and output. Due to the enormous size, complexity, and malleability of the titin molecule, titin properties are also vulnerable to dysregulation, as observed in various cardiac disorders. This review provides an overview of how cardiac titin properties can be changed at a molecular level, including the role isoform diversity and post-translational modifications (acetylation, oxidation, and phosphorylation) play in regulating myocardial stiffness and contractility. We then consider how this regulation becomes unbalanced in heart disease, with an emphasis on changes in titin stiffness and protein quality control. In this context, new insights into the key pathomechanisms of human cardiomyopathy due to a truncation in the titin gene (TTN) are discussed. Along the way, we touch on the potential for titin to be therapeutically targeted to treat acquired or inherited cardiac conditions, such as HFpEF or TTN-truncation cardiomyopathy.
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Affiliation(s)
- Christine M Loescher
- Institute of Physiology II, University Hospital Münster, Robert-Koch-Str. 27B, Münster, 48149 Germany
| | - Anastasia J Hobbach
- Department of Cardiology I, Coronary, Peripheral Vascular Disease and Heart Failure, University Hospital Münster, Münster, Germany
| | - Wolfgang A Linke
- Institute of Physiology II, University Hospital Münster, Robert-Koch-Str. 27B, Münster, 48149 Germany
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13
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Kosta S, Dauby PC. Frank-Starling mechanism, fluid responsiveness, and length-dependent activation: Unravelling the multiscale behaviors with an in silico analysis. PLoS Comput Biol 2021; 17:e1009469. [PMID: 34634040 PMCID: PMC8504729 DOI: 10.1371/journal.pcbi.1009469] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Accepted: 09/22/2021] [Indexed: 11/18/2022] Open
Abstract
The Frank-Starling mechanism is a fundamental regulatory property which underlies the cardiac output adaptation to venous filling. Length-dependent activation is generally assumed to be the cellular origin of this mechanism. At the heart scale, it is commonly admitted that an increase in preload (ventricular filling) leads to an increased cellular force and an increased volume of ejected blood. This explanation also forms the basis for vascular filling therapy. It is actually difficult to unravel the exact nature of the relationship between length-dependent activation and the Frank-Starling mechanism, as three different scales (cellular, ventricular and cardiovascular) are involved. Mathematical models are powerful tools to overcome these limitations. In this study, we use a multiscale model of the cardiovascular system to untangle the three concepts (length-dependent activation, Frank-Starling, and vascular filling). We first show that length-dependent activation is required to observe both the Frank-Starling mechanism and a positive response to high vascular fillings. Our results reveal a dynamical length dependent activation-driven response to changes in preload, which involves interactions between the cellular, ventricular and cardiovascular levels and thus highlights fundamentally multiscale behaviors. We show however that the cellular force increase is not enough to explain the cardiac response to rapid changes in preload. We also show that the absence of fluid responsiveness is not related to a saturating Frank-Starling effect. As it is challenging to study those multiscale phenomena experimentally, this computational approach contributes to a more comprehensive knowledge of the sophisticated length-dependent properties of cardiac muscle. It is commonly admitted that the length-dependent activation is the cellular property underlying the Frank-Starling mechanism. However, it is challenging to assess the cardiac cell length in vivo, and to link it to system-level variables. In this study, we investigated the relationship between length-dependent activation (LDA), the Frank-Starling mechanism, and vascular filling therapy using a multiscale model of the cardiovascular system. We showed that the Frank-Starling mechanism is a multiscale, dynamical and LDA-driven phenomenon involving essential connections between the three cellular, ventricular and cardiovascular scales. We also demonstrated that the response to vascular filling therapy is similarly multiscale and LDA-driven, and that afterload is an important factor to account for when trying to predict the system fluid responsiveness.
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Affiliation(s)
- Sarah Kosta
- GIGA–In Silico Medicine, University of Liège, Liège, Belgium
- * E-mail:
| | - Pierre C. Dauby
- GIGA–In Silico Medicine, University of Liège, Liège, Belgium
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14
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Crocini C, Gotthardt M. Cardiac sarcomere mechanics in health and disease. Biophys Rev 2021; 13:637-652. [PMID: 34745372 PMCID: PMC8553709 DOI: 10.1007/s12551-021-00840-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Accepted: 08/27/2021] [Indexed: 12/23/2022] Open
Abstract
The sarcomere is the fundamental structural and functional unit of striated muscle and is directly responsible for most of its mechanical properties. The sarcomere generates active or contractile forces and determines the passive or elastic properties of striated muscle. In the heart, mutations in sarcomeric proteins are responsible for the majority of genetically inherited cardiomyopathies. Here, we review the major determinants of cardiac sarcomere mechanics including the key structural components that contribute to active and passive tension. We dissect the molecular and structural basis of active force generation, including sarcomere composition, structure, activation, and relaxation. We then explore the giant sarcomere-resident protein titin, the major contributor to cardiac passive tension. We discuss sarcomere dynamics exemplified by the regulation of titin-based stiffness and the titin life cycle. Finally, we provide an overview of therapeutic strategies that target the sarcomere to improve cardiac contraction and filling.
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Affiliation(s)
- Claudia Crocini
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Neuromuscular and Cardiovascular Cell Biology, Berlin, Germany
- German Center for Cardiovascular Research (DZHK) Partner Site Berlin, Berlin, Germany
- BioFrontiers Institute & Department of Molecular and Cellular Development, University of Colorado Boulder, Boulder, USA
| | - Michael Gotthardt
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), Neuromuscular and Cardiovascular Cell Biology, Berlin, Germany
- German Center for Cardiovascular Research (DZHK) Partner Site Berlin, Berlin, Germany
- Charité-Universitätsmedizin Berlin, 10117 Berlin, Germany
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15
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Abstract
PURPOSE OF REVIEW This review aims to give an update on recent findings related to the cardiac splicing factor RNA-binding motif protein 20 (RBM20) and RBM20 cardiomyopathy, a form of dilated cardiomyopathy caused by mutations in RBM20. RECENT FINDINGS While most research on RBM20 splicing targets has focused on titin (TTN), multiple studies over the last years have shown that other splicing targets of RBM20 including Ca2+/calmodulin-dependent kinase IIδ (CAMK2D) might be critically involved in the development of RBM20 cardiomyopathy. In this regard, loss of RBM20 causes an abnormal intracellular calcium handling, which may relate to the arrhythmogenic presentation of RBM20 cardiomyopathy. In addition, RBM20 presents clinically in a highly gender-specific manner, with male patients suffering from an earlier disease onset and a more severe disease progression. Further research on RBM20, and treatment of RBM20 cardiomyopathy, will need to consider both the multitude and relative contribution of the different splicing targets and related pathways, as well as gender differences.
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16
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Stress-dependent activation of myosin in the heart requires thin filament activation and thick filament mechanosensing. Proc Natl Acad Sci U S A 2021; 118:2023706118. [PMID: 33850019 PMCID: PMC8072254 DOI: 10.1073/pnas.2023706118] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The efficiency of the heart as a pump depends on an autoregulatory mechanism, the Frank–Starling law of the heart, that potentiates the strength of contraction in response to an increase in ventricular filling. Disruption of this mechanism compromises the ability of the heart to pump blood, potentially leading to heart failure. We used fluorescent probes on myosin in heart muscle cells to investigate the molecular basis of the Frank–Starling mechanism. Our results show that the stronger contraction of heart muscle at longer lengths is due to a calcium-dependent interfilament signaling pathway that links stress sensing in the myosin-containing filaments with calcium activation of the actin-containing filaments. This pathway can potentially be targeted for treating heart failure. Myosin-based regulation in the heart muscle modulates the number of myosin motors available for interaction with calcium-regulated thin filaments, but the signaling pathways mediating the stronger contraction triggered by stretch between heartbeats or by phosphorylation of the myosin regulatory light chain (RLC) remain unclear. Here, we used RLC probes in demembranated cardiac trabeculae to investigate the molecular structural basis of these regulatory pathways. We show that in relaxed trabeculae at near-physiological temperature and filament lattice spacing, the RLC-lobe orientations are consistent with a subset of myosin motors being folded onto the filament surface in the interacting-heads motif seen in isolated filaments. The folded conformation of myosin is disrupted by cooling relaxed trabeculae, similar to the effect induced by maximal calcium activation. Stretch or increased RLC phosphorylation in the physiological range have almost no effect on RLC conformation at a calcium concentration corresponding to that between beats. These results indicate that in near-physiological conditions, the folded myosin motors are not directly switched on by RLC phosphorylation or by the titin-based passive tension at longer sarcomere lengths in the absence of thin filament activation. However, at the higher calcium concentrations that activate the thin filaments, stretch produces a delayed activation of folded myosin motors and force increase that is potentiated by RLC phosphorylation. We conclude that the increased contractility of the heart induced by RLC phosphorylation and stretch can be explained by a calcium-dependent interfilament signaling pathway involving both thin filament sensitization and thick filament mechanosensing.
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17
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de Lange WJ, Farrell ET, Kreitzer CR, Jacobs DR, Lang D, Glukhov AV, Ralphe JC. Human iPSC-engineered cardiac tissue platform faithfully models important cardiac physiology. Am J Physiol Heart Circ Physiol 2021; 320:H1670-H1686. [PMID: 33606581 DOI: 10.1152/ajpheart.00941.2020] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Cardiomyocytes derived from human induced pluripotent stem cells (hiPSC-CM) may provide an important bridge between animal models and the intact human myocardium. Fulfilling this potential is hampered by their relative immaturity, leading to poor physiological responsiveness. hiPSC-CMs grown in traditional two-dimensional (2D) culture lack a t-tubular system, have only rudimentary intracellular calcium-handling systems, express predominantly embryonic sarcomeric protein isoforms, and preferentially use glucose as an energy substrate. Culturing hiPSC-CM in a variety of three-dimensional (3D) environments and the addition of nutritional, pharmacological, and electromechanical stimuli have proven, to various degrees, to be beneficial for maturation. We present a detailed assessment of a novel model in which hiPSC-CMs and hiPSC-derived cardiac fibroblasts are cocultured in a 3D fibrin matrix to form engineered cardiac tissue constructs (hiPSC-ECTs). The hiPSC-ECTs are responsive to physiological stimuli, including stretch, frequency, and β-adrenergic stimulation, develop a t-tubular system, and demonstrate calcium-handling and contractile kinetics that compare favorably with ventricular human myocardium. Furthermore, transcript levels of various genes involved in calcium-handling and contraction are increased. These markers of maturation become more robust over a relatively short period of time in culture (6 wk vs. 2 wk in hiPSC-ECTs). A comparison of the hiPSC-ECT molecular and performance variables with those of human cardiac tissue and other available engineered tissue platforms is provided to aid selection of the most appropriate platform for the research question at hand. Important and noteworthy aspects of this human cardiac model system are its reliance on "off-the-shelf" equipment, ability to provide detailed physiological performance data, and the ability to achieve a relatively mature cardiac physiology without additional nutritional, pharmacological, and electromechanical stimuli that may elicit unintended effects on function.NEW & NOTEWORTHY This study seeks to provide an in-depth assessment of contractile performance of human iPSC-derived cardiomyocytes cultured together with fibroblasts in a 3-dimensional-engineered tissue and compares performance both over time as cells mature, and with corresponding measures found in the literature using alternative 3D culture configurations. The suitability of 3D-engineered human cardiac tissues to model cardiac function is emphasized, and data provided to assist in the selection of the most appropriate configuration based on the target application.
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Affiliation(s)
- Willem J de Lange
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Emily T Farrell
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Caroline R Kreitzer
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Derek R Jacobs
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Di Lang
- Department of Medicine Cardiovascular Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - Alexey V Glukhov
- Department of Medicine Cardiovascular Medicine, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin
| | - J Carter Ralphe
- Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
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18
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Piroddi N, Pesce P, Scellini B, Manzini S, Ganzetti GS, Badi I, Menegollo M, Cora V, Tiso S, Cinquetti R, Monti L, Chiesa G, Bleyl SB, Busnelli M, Dellera F, Bruno D, Caicci F, Grimaldi A, Taramelli R, Manni L, Sacerdoti D, Tesi C, Poggesi C, Ausoni S, Acquati F, Campione M. Myocardial overexpression of ANKRD1 causes sinus venosus defects and progressive diastolic dysfunction. Cardiovasc Res 2021; 116:1458-1472. [PMID: 31688894 DOI: 10.1093/cvr/cvz291] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 09/26/2019] [Accepted: 10/30/2019] [Indexed: 12/11/2022] Open
Abstract
AIMS Increased Ankyrin Repeat Domain 1 (ANKRD1) levels linked to gain of function mutations have been associated to total anomalous pulmonary venous return and adult cardiomyopathy occurrence in humans. The link between increased ANKRD1 level and cardiac structural and functional disease is not understood. To get insight into this problem, we have generated a gain of function ANKRD1 mouse model by overexpressing ANKRD1 in the myocardium. METHODS AND RESULTS Ankrd1 is expressed non-homogeneously in the embryonic myocardium, with a dynamic nucleo-sarcomeric localization in developing cardiomyocytes. ANKRD1 transgenic mice present sinus venosus defect, which originates during development by impaired remodelling of early embryonic heart. Adult transgenic hearts develop diastolic dysfunction with preserved ejection fraction, which progressively evolves into heart failure, as shown histologically and haemodynamically. Transgenic cardiomyocyte structure, sarcomeric assembly, and stability are progressively impaired from embryonic to adult life. Postnatal transgenic myofibrils also present characteristic functional alterations: impaired compliance at neonatal stage and impaired lusitropism in adult hearts. Altogether, our combined analyses suggest that impaired embryonic remodelling and adult heart dysfunction in ANKRD1 transgenic mice present a common ground of initial cardiomyocyte defects, which are exacerbated postnatally. Molecular analysis showed transient activation of GATA4-Nkx2.5 transcription in early transgenic embryos and subsequent dynamic transcriptional modulation within titin gene. CONCLUSIONS ANKRD1 is a fine mediator of cardiomyocyte response to haemodynamic load in the developing and adult heart. Increased ANKRD1 levels are sufficient to initiate an altered cellular phenotype, which is progressively exacerbated into a pathological organ response by the high ventricular workload during postnatal life. Our study defines for the first time a unifying picture for ANKRD1 role in heart development and disease and provides the first mechanistic link between ANKRD1 overexpression and cardiac disease onset.
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Affiliation(s)
- Nicoletta Piroddi
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Paola Pesce
- Department of Medicine, University of Padua, 35121 Padua, Italy
| | - Beatrice Scellini
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Stefano Manzini
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Giulia S Ganzetti
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Ileana Badi
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy.,Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DU, UK
| | - Michela Menegollo
- Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy
| | - Virginia Cora
- Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy
| | - Simone Tiso
- Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy
| | - Raffaella Cinquetti
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Laura Monti
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Giulia Chiesa
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Steven B Bleyl
- Department of Pediatrics, University of Utah, Salt Lake City, 84132 UT, USA
| | - Marco Busnelli
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Federica Dellera
- Department of Pharmacological and Biomolecular Sciences, University of Milan, 20133 Milan, Italy
| | - Daniele Bruno
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Federico Caicci
- Department of Biology, University of Padua, 35121 Padua, Italy
| | - Annalisa Grimaldi
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Roberto Taramelli
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Lucia Manni
- Department of Biology, University of Padua, 35121 Padua, Italy
| | - David Sacerdoti
- Department of Medicine, University of Padua, 35121 Padua, Italy
| | - Chiara Tesi
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Corrado Poggesi
- Department of Experimental and Clinical Medicine, University of Florence, 50134 Florence, Italy
| | - Simonetta Ausoni
- Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy
| | - Francesco Acquati
- Department of Biotechnology and Life Sciences, University of Insubria, 21100 Varese, Italy
| | - Marina Campione
- Department of Biomedical Sciences, University of Padua, 35121 Padua, Italy.,CNR-Neuroscience Institute, 35121 Padua, Italy
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19
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Habigt MA, Krieger M, Gesenhues J, Ketelhut M, Mechelinck M, Hein M. Non-linearity of end-systolic pressure-volume relation in afterload increases is caused by an overlay of shortening deactivation and the Frank-Starling mechanism. Sci Rep 2021; 11:3353. [PMID: 33558620 PMCID: PMC7870877 DOI: 10.1038/s41598-021-82791-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 01/19/2021] [Indexed: 11/09/2022] Open
Abstract
The linearity and load insensitivity of the end-systolic pressure-volume-relationship (ESPVR), a parameter that describes the ventricular contractile state, are controversial. We hypothesize that linearity is influenced by a variable overlay of the intrinsic mechanism of autoregulation to afterload (shortening deactivation) and preload (Frank-Starling mechanism). To study the effect of different short-term loading alterations on the shape of the ESPVR, experiments on twenty-four healthy pigs were executed. Preload reductions, afterload increases and preload reductions while the afterload level was increased were performed. The ESPVR was described either by a linear or a bilinear regression through the end-systolic pressure volume (ES-PV) points. Increases in afterload caused a biphasic course of the ES-PV points, which led to a better fit of the bilinear ESPVRs (r2 0.929 linear ESPVR vs. r2 0.96 and 0.943 bilinear ESPVR). ES-PV points of a preload reduction on a normal and augmented afterload level could be well described by a linear regression (r2 0.974 linear ESPVR vs. r2 0.976 and 0.975 bilinear ESPVR). The intercept of the second ESPVR (V0) but not the slope demonstrated a significant linear correlation with the reached afterload level (effective arterial elastance Ea). Thus, the early response to load could be described by the fixed slope of the ESPVR and variable V0, which was determined by the actual afterload. The ESPVR is only apparently nonlinear, as its course over several heartbeats was affected by an overlay of SDA and FSM. These findings could be easily transferred to cardiovascular simulation models to improve their accuracy.
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Affiliation(s)
- Moriz A Habigt
- Anaesthesiology Clinic, University Hospital RWTH Aachen, Pauwelsstr. 30, 52074, Aachen, Germany.
| | - Michelle Krieger
- Anaesthesiology Clinic, University Hospital RWTH Aachen, Pauwelsstr. 30, 52074, Aachen, Germany
| | - Jonas Gesenhues
- Institute of Automatic Control, RWTH Aachen University, Steinbachstr. 54, 52074, Aachen, Germany
| | - Maike Ketelhut
- Institute of Automatic Control, RWTH Aachen University, Steinbachstr. 54, 52074, Aachen, Germany
| | - Mare Mechelinck
- Anaesthesiology Clinic, University Hospital RWTH Aachen, Pauwelsstr. 30, 52074, Aachen, Germany
| | - Marc Hein
- Anaesthesiology Clinic, University Hospital RWTH Aachen, Pauwelsstr. 30, 52074, Aachen, Germany
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20
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Mechanism of contraction rhythm homeostasis for hyperthermal sarcomeric oscillations of neonatal cardiomyocytes. Sci Rep 2020; 10:20468. [PMID: 33235297 PMCID: PMC7687892 DOI: 10.1038/s41598-020-77443-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 11/10/2020] [Indexed: 11/08/2022] Open
Abstract
The heart rhythm is maintained by oscillatory changes in [Ca2+]. However, it has been suggested that the rapid drop in blood pressure that occurs with a slow decrease in [Ca2+] preceding early diastolic filling is related to the mechanism of rapid sarcomere lengthening associated with spontaneous tension oscillation at constant intermediate [Ca2+]. Here, we analyzed a new type of oscillation called hyperthermal sarcomeric oscillation. Sarcomeres in rat neonatal cardiomyocytes that were warmed at 38-42 °C oscillated at both slow (~ 1.4 Hz), Ca2+-dependent frequencies and fast (~ 7 Hz), Ca2+-independent frequencies. Our high-precision experimental observations revealed that the fast sarcomeric oscillation had high and low peak-to-peak amplitude at low and high [Ca2+], respectively; nevertheless, the oscillation period remained constant. Our numerical simulations suggest that the regular and fast rthythm is maintained by the unchanged cooperative binding behavior of myosin molecules during slow oscillatory changes in [Ca2+].
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21
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Regazzoni F, Dedè L, Quarteroni A. Biophysically detailed mathematical models of multiscale cardiac active mechanics. PLoS Comput Biol 2020; 16:e1008294. [PMID: 33027247 PMCID: PMC7571720 DOI: 10.1371/journal.pcbi.1008294] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Revised: 10/19/2020] [Accepted: 08/27/2020] [Indexed: 11/19/2022] Open
Abstract
We propose four novel mathematical models, describing the microscopic mechanisms of force generation in the cardiac muscle tissue, which are suitable for multiscale numerical simulations of cardiac electromechanics. Such models are based on a biophysically accurate representation of the regulatory and contractile proteins in the sarcomeres. Our models, unlike most of the sarcomere dynamics models that are available in the literature and that feature a comparable richness of detail, do not require the time-consuming Monte Carlo method for their numerical approximation. Conversely, the models that we propose only require the solution of a system of PDEs and/or ODEs (the most reduced of the four only involving 20 ODEs), thus entailing a significant computational efficiency. By focusing on the two models that feature the best trade-off between detail of description and identifiability of parameters, we propose a pipeline to calibrate such parameters starting from experimental measurements available in literature. Thanks to this pipeline, we calibrate these models for room-temperature rat and for body-temperature human cells. We show, by means of numerical simulations, that the proposed models correctly predict the main features of force generation, including the steady-state force-calcium and force-length relationships, the length-dependent prolongation of twitches and increase of peak force, the force-velocity relationship. Moreover, they correctly reproduce the Frank-Starling effect, when employed in multiscale 3D numerical simulation of cardiac electromechanics.
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Affiliation(s)
- Francesco Regazzoni
- MOX - Dipartimento di Matematica, Politecnico di Milano, P.zza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Luca Dedè
- MOX - Dipartimento di Matematica, Politecnico di Milano, P.zza Leonardo da Vinci 32, 20133 Milano, Italy
| | - Alfio Quarteroni
- MOX - Dipartimento di Matematica, Politecnico di Milano, P.zza Leonardo da Vinci 32, 20133 Milano, Italy
- Mathematics Institute, École Polytechnique Fédérale de Lausanne, Av. Piccard, CH-1015 Lausanne, Switzerland (Professor Emeritus)
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Boldt K, Han SW, Joumaa V, Herzog W. Residual and passive force enhancement in skinned cardiac fibre bundles. J Biomech 2020; 109:109953. [PMID: 32807325 DOI: 10.1016/j.jbiomech.2020.109953] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 07/06/2020] [Accepted: 07/08/2020] [Indexed: 11/28/2022]
Abstract
In skeletal muscle, steady-state force is consistently greater following active stretch than during a purely isometric contraction at the same length (residual force enhancement; RFE). Similarly, when deactivated, the force remains higher following active stretch than following an isometric condition (passive force enhancement; PFE). RFE and PFE have been associated with the sarcomere protein titin, but skeletal and cardiac titin have different structures, and results regarding RFE in cardiac muscle have been inconsistent and contradictory. Therefore, the purpose of this study was to determine if cardiac muscle exhibits RFE and PFE. Skinned fibre bundles (n = 10) were activated isometrically at a sarcomere length of 2.2 μm and actively stretched by 15% of their length. The resultant active and passive forces were compared to the corresponding forces obtained for purely isometric contractions at the long length. RFE was observed in all fibre bundles, averaging 5.5 ± 2.5% (ranging from 2.3 to 9.4%). PFE was observed in nine of the ten bundles, averaging 11.1 ± 6.5% (ranging from -2.1 to 18.7%). Stiffness was not different between the active isometric and the force enhanced conditions, but was higher following deactivation from the force-enhanced compared to the isometric reference state. We conclude that there is RFE and PFE in cardiac muscle. We speculate that cardiac muscle has the same RFE capability as skeletal muscle, and that the most likely mechanism for the RFE and PFE is the engagement of a passive structural element during active stretching.
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Affiliation(s)
- Kevin Boldt
- Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, Canada.
| | - Seong-Won Han
- Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, Canada
| | - Venus Joumaa
- Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, Canada
| | - Walter Herzog
- Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, Canada
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Kuhtz-Buschbeck JP, Schaefer J, Wilder N, Wolze WT. The origin of the heartbeat and theories of muscle contraction. Physiological concepts and conflicts in the 19th century. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 159:3-9. [PMID: 32622835 DOI: 10.1016/j.pbiomolbio.2020.05.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 04/27/2020] [Accepted: 05/28/2020] [Indexed: 11/19/2022]
Abstract
The origin of the incessant rhythmical heartbeat and the mechanism of muscle contraction have fascinated scientists over centuries. This short review outlines physiological explanations that were discussed in the 19th century starting with Albrecht von Haller (1708-1777), an 18th century physiologist who proposed that the heart has an intrinsic irritability. He argued that under normal conditions the inflow of blood stimulates the heart muscle to contract by mechanical touch and distension. Johannes Müller (1800-1858, physiologist in Bonn and Berlin) contended that the influence of the sympathetic nerve, specifically the activity of intracardiac ganglia, is the foremost cause of the heartbeat. Walter H. Gaskell and Theodor Engelmann (physiologists in Cambridge and Utrecht, respectively) independently criticized this neurogenic theory. They reported experimental evidence that supported the myogenic theory of the origin of the heartbeat, which has been accepted since about 1900. The concept of cardiac mechano-sensitivity, which can be traced back to A. von Haller, is currently resurging. Concerning mechanisms of contraction, Edward A. Schäfer (1850-1935), histologist and physiologist in Edinburgh, described differences between cardiac and skeletal muscle and coined the term sarcomere. Based on microscopic studies of cross-striated muscle, Schäfer outlined a detailed and plausible mechanism of muscle contraction in 1892. He put forward that during muscle shortening the "clear part of the muscle substance" (actin) might pass into longitudinal canals, which exist between the "sarcous elements" (myosin). His model foresaw fundamental elements of the sliding filament model, which was discovered by the Huxleys about 60 years later.
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Affiliation(s)
| | - Jochen Schaefer
- International Institute for Theoretical Cardiology, Kiel, Germany
| | - Nicolaus Wilder
- Institut für Pädagogik, Christian-Albrechts-Universität Kiel, Germany
| | - Wilhelm T Wolze
- Zentrum für konstruktive Erziehungswissenschaften, Christian-Albrechts-Universität Kiel, Germany
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Muir WW, Hamlin RL. Myocardial Contractility: Historical and Contemporary Considerations. Front Physiol 2020; 11:222. [PMID: 32296340 PMCID: PMC7137917 DOI: 10.3389/fphys.2020.00222] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 02/26/2020] [Indexed: 12/17/2022] Open
Abstract
The term myocardial contractility is thought to have originated more than 125 years ago and has remained and enigma ever since. Although the term is frequently used in textbooks, editorials and contemporary manuscripts its definition remains illusive often being conflated with cardiac performance or inotropy. The absence of a universally accepted definition has led to confusion, disagreement and misconceptions among physiologists, cardiologists and safety pharmacologists regarding its definition particularly in light of new discoveries regarding the load dependent kinetics of cardiac contraction and their translation to cardiac force-velocity and ventricular pressure-volume measurements. Importantly, the Starling interpretation of force development is length-dependent while contractility is length independent. Most historical definitions employ an operational approach and define cardiac contractility in terms of the hearts mechanical properties independent of loading conditions. Literally defined the term contract infers that something has become smaller, shrunk or shortened. The addition of the suffix “ility” implies the quality of this process. The discovery and clinical investigation of small molecules that bind to sarcomeric proteins independently altering force or velocity requires that a modern definition of the term myocardial contractility be developed if the term is to persist. This review reconsiders the historical and contemporary interpretations of the terms cardiac performance and inotropy and recommends a modern definition of myocardial contractility as the preload, afterload and length-independent intrinsic kinetically controlled, chemo-mechanical processes responsible for the development of force and velocity.
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Affiliation(s)
- William W Muir
- College of Veterinary Medicine, Lincoln Memorial University, Harrogate, TN, United States
| | - Robert L Hamlin
- College of Veterinary Medicine, The Ohio State University, Columbus, OH, United States
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Vallée A, Lecarpentier Y. TGF-β in fibrosis by acting as a conductor for contractile properties of myofibroblasts. Cell Biosci 2019; 9:98. [PMID: 31827764 PMCID: PMC6902440 DOI: 10.1186/s13578-019-0362-3] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 11/30/2019] [Indexed: 12/21/2022] Open
Abstract
Myofibroblasts are non-muscle contractile cells that play a key physiologically role in organs such as the stem villi of the human placenta during physiological pregnancy. They are able to contract and relax in response to changes in the volume of the intervillous chamber. Myofibroblasts have also been observed in several diseases and are involved in wound healing and the fibrotic processes affecting several organs, such as the liver, lungs, kidneys and heart. During the fibrotic process, tissue retraction rather than contraction is correlated with collagen synthesis in the extracellular matrix, leading to irreversible fibrosis and, finally, apoptosis of myofibroblasts. The molecular motor of myofibroblasts is the non-muscle type IIA and B myosin (NMMIIA and NMMIIB). Fibroblast differentiation into myofibroblasts is largely governed by the transforming growth factor-β1 (TGF-β1). This system controls the canonical WNT/β-catenin pathway in a positive manner, and PPARγ in a negative manner. The WNT/β-catenin pathway promotes fibrosis, while PPARγ prevents it. This review focuses on the contractile properties of myofibroblasts and the conductor, TGF-β1, which together control the opposing interplay between PPARγ and the canonical WNT/β-catenin pathway.
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Affiliation(s)
- Alexandre Vallée
- 1Délégation à la Recherche Clinique (DRCI), Hôpital Foch, Suresnes, France.,DACTIM-MIS, Laboratoire de Mathématiques et Applications (LMA), CNRS, UMR 7348, Université de Poitiers, CHU de Poitiers, Poitiers, France
| | - Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l'Est Francilien (GHEF), Meaux, France
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Special Issue: The Actin-Myosin Interaction in Muscle: Background and Overview. Int J Mol Sci 2019; 20:ijms20225715. [PMID: 31739584 PMCID: PMC6887992 DOI: 10.3390/ijms20225715] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 10/15/2019] [Indexed: 12/12/2022] Open
Abstract
Muscular contraction is a fundamental phenomenon in all animals; without it life as we know it would be impossible. The basic mechanism in muscle, including heart muscle, involves the interaction of the protein filaments myosin and actin. Motility in all cells is also partly based on similar interactions of actin filaments with non-muscle myosins. Early studies of muscle contraction have informed later studies of these cellular actin-myosin systems. In muscles, projections on the myosin filaments, the so-called myosin heads or cross-bridges, interact with the nearby actin filaments and, in a mechanism powered by ATP-hydrolysis, they move the actin filaments past them in a kind of cyclic rowing action to produce the macroscopic muscular movements of which we are all aware. In this special issue the papers and reviews address different aspects of the actin-myosin interaction in muscle as studied by a plethora of complementary techniques. The present overview provides a brief and elementary introduction to muscle structure and function and the techniques used to study it. It goes on to give more detailed descriptions of what is known about muscle components and the cross-bridge cycle using structural biology techniques, particularly protein crystallography, electron microscopy and X-ray diffraction. It then has a quick look at muscle mechanics and it summarises what can be learnt about how muscle works based on the other studies covered in the different papers in the special issue. A picture emerges of the main molecular steps involved in the force-producing process; steps that are also likely to be seen in non-muscle myosin interactions with cellular actin filaments. Finally, the remarkable advances made in studying the effects of mutations in the contractile assembly in causing specific muscle diseases, particularly those in heart muscle, are outlined and discussed.
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Tomalka A, Röhrle O, Han JC, Pham T, Taberner AJ, Siebert T. Extensive eccentric contractions in intact cardiac trabeculae: revealing compelling differences in contractile behaviour compared to skeletal muscles. Proc Biol Sci 2019; 286:20190719. [PMID: 31138072 DOI: 10.1098/rspb.2019.0719] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Force enhancement (FE) is a phenomenon that is present in skeletal muscle. It is characterized by progressive forces upon active stretching-distinguished by a linear rise in force-and enhanced isometric force following stretching (residual FE (RFE)). In skeletal muscle, non-cross-bridge (XB) structures may account for this behaviour. So far, it is unknown whether differences between non-XB structures within the heart and skeletal muscle result in deviating contractile behaviour during and after eccentric contractions. Thus, we investigated the force response of intact cardiac trabeculae during and after isokinetic eccentric muscle contractions (10% of maximum shortening velocity) with extensive magnitudes of stretch (25% of optimum muscle length). The different contributions of XB and non-XB structures to the total muscle force were revealed by using an actomyosin inhibitor. For cardiac trabeculae, we found that the force-length dynamics during long stretch were similar to the total isometric force-length relation. This indicates that no (R)FE is present in cardiac muscle while stretching the muscle from 0.75 to 1.0 optimum muscle length. This finding is in contrast with the results obtained for skeletal muscle, in which (R)FE is present. Our data support the hypothesis that titin stiffness does not increase with activation in cardiac muscle.
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Affiliation(s)
- André Tomalka
- 1 Department of Motion and Exercise Science, University of Stuttgart , Stuttgart , Germany
| | - Oliver Röhrle
- 2 Institute of Applied Mechanics (Civil Engineering), University of Stuttgart , Stuttgart , Germany.,3 Cluster of Excellence for Simulation Technology (SimTech) , Stuttgart , Germany
| | - June-Chiew Han
- 4 Auckland Bioengineering Institute, The University of Auckland , Auckland , New Zealand
| | - Toan Pham
- 5 Department of Physiology, The University of Auckland , Auckland , New Zealand
| | - Andrew J Taberner
- 4 Auckland Bioengineering Institute, The University of Auckland , Auckland , New Zealand.,6 Department of Engineering Science, The University of Auckland , Auckland , New Zealand
| | - Tobias Siebert
- 1 Department of Motion and Exercise Science, University of Stuttgart , Stuttgart , Germany
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Lookin O, Protsenko Y. The lack of slow force response in failing rat myocardium: role of stretch-induced modulation of Ca-TnC kinetics. J Physiol Sci 2019; 69:345-357. [PMID: 30560346 PMCID: PMC10717443 DOI: 10.1007/s12576-018-0651-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 12/08/2018] [Indexed: 10/27/2022]
Abstract
The slow force response (SFR) to stretch is an important adaptive mechanism of the heart. The SFR may result in ~ 20-30% extra force but it is substantially attenuated in heart failure. We investigated the relation of SFR magnitude with Ca2+ transient decay in healthy (CONT) and monocrotaline-treated rats with heart failure (MCT). Right ventricular trabeculae were stretched from 85 to 95% of optimal length and held stretched for 10 min at 30 °C and 1 Hz. Isometric twitches and Ca2+ transients were collected on 2, 4, 6, 8, 10 min after stretch. The changes in peak tension and Ca2+ transient decay characteristics during SFR were evaluated as a percentage of the value measured immediately after stretch. The amount of Ca2+ utilized by TnC was indirectly evaluated using the methods of Ca2+ transient "bump" and "difference curve." The muscles of CONT rats produced positive SFR and they showed prominent functional relation between SFR magnitude and the magnitude (amplitude, integral intensity) of Ca2+ transient "bump" and "difference curve." The myocardium of MCT rats showed negative SFR to stretch (force decreased in time) which was not correlated well with the characteristics of Ca2+ transient decay, evaluated by the methods of "bump" and "difference curve." We conclude that the intracellular mechanisms of Ca2+ balancing during stretch-induced slow adaptation of myocardial contractility are disrupted in failing rat myocardium. The potential significance of our findings is that the deficiency of slow force response in diseased myocardium may be diminished under augmented kinetics of Ca-TnC interaction.
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Affiliation(s)
- Oleg Lookin
- Laboratory of Biological Motility, Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya St., Yekaterinburg, 620049, Russian Federation.
- Ural Federal University, 19 Mira St., Yekaterinburg, 620002, Russian Federation.
| | - Yuri Protsenko
- Laboratory of Biological Motility, Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya St., Yekaterinburg, 620049, Russian Federation
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Thompson LC, Kim YH, Martin BL, Ledbetter AD, Dye JA, Hazari MS, Gilmour MI, Farraj AK. Pulmonary exposure to peat smoke extracts in rats decreases expiratory time and increases left heart end systolic volume. Inhal Toxicol 2019; 30:439-447. [PMID: 30642191 DOI: 10.1080/08958378.2018.1551443] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Exposure to wildland fire-related particulate matter (PM) causes adverse health outcomes. However, the impacts of specific biomass sources remain unclear. The purpose of this study was to investigate cardiopulmonary responses in rats following exposure to PM extracts collected from peat fire smoke. We hypothesized that peat smoke PM would dose-dependently alter cardiopulmonary function. Male Sprague-Dawley rats (n = 8/group) were exposed to 35 µg (Lo PM) or 350 µg (Hi PM) of peat smoke PM extracts suspended in saline, or saline alone (Vehicle) via oropharyngeal aspiration (OA). Ventilatory expiration times, measured in whole-body plethysmographs immediately after OA, were the lowest in Hi PM exposed subjects at 6 min into recovery (p = .01 vs. Lo PM, p = .08 vs. Vehicle) and resolved shortly afterwards. The next day, we evaluated cardiovascular function in the same subjects via cardiac ultrasound under isoflurane anesthesia. Compared to Vehicle, Hi PM had 45% higher end systolic volume (p = .03) and 17% higher pulmonary artery blood flow acceleration/ejection time ratios, and both endpoints expressed significant increasing linear trends by dose (p = .01 and .02, respectively). In addition, linear trend analyses across doses detected an increase for end diastolic volume and decreases for ejection fraction and fractional shortening. These data suggest that exposure to peat smoke constituents modulates regulation of ventricular ejection and filling volumes, which could be related to altered blood flow in the pulmonary circulation. Moreover, early pulmonary responses to peat smoke PM point to irritant/autonomic mechanisms as potential drivers of later cardiovascular responses.
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Affiliation(s)
- Leslie C Thompson
- a US Environmental Protection Agency, Environmental Public Health Division , Durham , NC , USA
| | - Yong Ho Kim
- a US Environmental Protection Agency, Environmental Public Health Division , Durham , NC , USA.,b National Research Council , Washington , DC , USA
| | - Brandi L Martin
- c Oak Ridge Institute for Science and Education , Oak Ridge , TN , USA
| | - Allen D Ledbetter
- a US Environmental Protection Agency, Environmental Public Health Division , Durham , NC , USA
| | - Janice A Dye
- a US Environmental Protection Agency, Environmental Public Health Division , Durham , NC , USA
| | - Mehdi S Hazari
- a US Environmental Protection Agency, Environmental Public Health Division , Durham , NC , USA
| | - M Ian Gilmour
- a US Environmental Protection Agency, Environmental Public Health Division , Durham , NC , USA
| | - Aimen K Farraj
- a US Environmental Protection Agency, Environmental Public Health Division , Durham , NC , USA
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Caruel M, Moireau P, Chapelle D. Stochastic modeling of chemical–mechanical coupling in striated muscles. Biomech Model Mechanobiol 2019; 18:563-587. [DOI: 10.1007/s10237-018-1102-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 11/21/2018] [Indexed: 01/15/2023]
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31
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Corazza I, Casadei L, Bonafè E, Cercenelli L, Marcelli E, Zannoli R. How to transform a fixed stroke alternating syringe ventricle into an adjustable elastance ventricle. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:074301. [PMID: 30068143 DOI: 10.1063/1.5030100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Most devices used for bench simulation of the cardiovascular system are based either on a syringe-like alternating pump or an elastic chamber inside a fluid-filled rigid box. In these devices, it is very difficult to control the ventricular elastance and simulate pathologies related to the mechanical mismatch between the ventricle and arterial load (i.e., heart failure). This work presents a possible solution to transforming a syringe-like pump with a fixed ventricle into a ventricle with variable elastance. Our proposal was tested in two steps: (1) fixing the ventricle and the aorta and changing the peripheral resistance (PHR); (2) fixing the aorta and changing the ventricular elastance and the PHR. The signals of interest were acquired to build the ventricular pressure-volume (P-V) loops describing the different physiological conditions, and the end-systolic pressure-volume relationships (ESPVRs) were calculated with linear interpolation. The results obtained show a good physiological behavior of our mock for both steps. (1) Since the ventricle is the same, the systolic pressures increase and the stroke volumes decrease with the PHR: the ESPVR, obtained by interpolating the pressure and volume values at end-systolic phases, is linear. (2) Each ventricle presents ESPVR with different slopes depending on the ventricle elastance with a very good linear behavior. In conclusion, this paper demonstrates that a fixed stroke alternating syringe ventricle can be transformed into an adjustable elastance ventricle.
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Affiliation(s)
- Ivan Corazza
- Experimental, Diagnostic and Specialty Medicine Department, University of Bologna, Bologna, Italy
| | - Lorenzo Casadei
- Experimental, Diagnostic and Specialty Medicine Department, University of Bologna, Bologna, Italy
| | - Elisa Bonafè
- Experimental, Diagnostic and Specialty Medicine Department, University of Bologna, Bologna, Italy
| | - Laura Cercenelli
- Experimental, Diagnostic and Specialty Medicine Department, University of Bologna, Bologna, Italy
| | - Emanuela Marcelli
- Experimental, Diagnostic and Specialty Medicine Department, University of Bologna, Bologna, Italy
| | - Romano Zannoli
- Experimental, Diagnostic and Specialty Medicine Department, University of Bologna, Bologna, Italy
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Schiffner R, Nistor M, Bischoff SJ, Matziolis G, Schmidt M, Lehmann T. Effects of human relaxin-2 (serelaxin) on hypoxic pulmonary vasoconstriction during acute hypoxia in a sheep model. HYPOXIA (AUCKLAND, N.Z.) 2018; 6:11-22. [PMID: 29862306 PMCID: PMC5968803 DOI: 10.2147/hp.s165092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Purpose Hypoxia induces pulmonary vasoconstriction with a subsequent increase of pulmonary artery pressure (PAP), which can result in pulmonary hypertension. Serelaxin has shown an increase of pulmonary hemodynamic parameters after serelaxin injection. We therefore investigated the response of pulmonary hemodynamic parameters after serelaxin administration in a clinically relevant model. Methods Six controls and six sheep that received 30 μg/kg serelaxin underwent right heart catheterization during a 12-minute hypoxia period (inhalation of 5% oxygen and 95% nitrogen) and subsequent reoxygenation. Systolic, diastolic, and mean values of both PAP (respectively, PAPs, PAPd, and PAPm) and pulmonary capillary wedge pressure (respectively, PCWPs, PCWPd, and PCWPm), blood gases, heart rate (HR), and both peripheral and pulmonary arterial oxygen saturation were obtained. Cardiac output (CO), stroke volume (SV), pulmonary vascular resistance (PVR), pulmonary arterial compliance (PAcompl), and systemic vascular resistance (SVR) were calculated. Results The key findings of the current study are that serelaxin prevents the rise of PAPs (p≤0.001), PAPm, PCWPm, PCWPs (p≤0.03), and PAPd (p≤0.05) during hypoxia, while it simultaneously increases CO and SV (p≤0.001). Similar courses of decreases of PAPm, PAPd, PAPs, CO, SVR (p≤0.001), and PCWPd (p≤0.03) as compared to hypoxic values were observed during reoxygenation. In direct comparison, the experimental groups differed during hypoxia in regard to HR, PAPm, PVR, and SVR (p≤0.03), and during reoxygenation in regard to HR (p≤0.001), PAPm, PAPs, PAPd, PVR, SVR (p≤0.03), and PCWPd (p≤0.05). Conclusion The findings of this study suggest that serelaxin treatment improves pulmonary hemodynamic parameters during acute hypoxia.
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Affiliation(s)
| | | | | | | | | | - Thomas Lehmann
- Institute of Medical Statistics, Computer Sciences and Documentation Science, Jena University Hospital, Friedrich Schiller University, Jena, Germany
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Stretch your heart-but not too far: The role of titin mutations in dilated cardiomyopathy. J Thorac Cardiovasc Surg 2018; 156:209-214. [PMID: 29685583 DOI: 10.1016/j.jtcvs.2017.10.160] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 09/29/2017] [Accepted: 10/24/2017] [Indexed: 12/23/2022]
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Dos Remedios CG, Li A. Editorial for issue #1 2018. Biophys Rev 2018; 10:1-2. [PMID: 29280063 PMCID: PMC5803178 DOI: 10.1007/s12551-017-0385-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 12/13/2017] [Indexed: 10/18/2022] Open
Affiliation(s)
| | - A Li
- University of Vermont, Burlington, VT, USA
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Khokhlova A, Iribe G, Katsnelson L, Naruse K, Solovyova O. The effects of load on transmural differences in contraction of isolated mouse ventricular cardiomyocytes. J Mol Cell Cardiol 2017; 114:276-287. [PMID: 29217431 DOI: 10.1016/j.yjmcc.2017.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Accepted: 12/01/2017] [Indexed: 12/31/2022]
Abstract
Mechanical properties of cardiomyocytes from different transmural regions are heterogeneous in the left ventricular wall. The cardiomyocyte mechanical environment affects this heterogeneity because of mechano-electric feedback mechanisms. In the present study, we investigated the effects of the mechanical load (preload and afterload) on transmural differences in contraction of subendocardial (ENDO) and subepicardial (EPI) single cells isolated from the murine left ventricle. Various preloads imposed via axial stretch and afterloads (unloaded and heavy loaded conditions) were applied to the cells using carbon fiber techniques for single myocytes. To simulate experimentally obtained results and to predict mechanisms underlying the cellular response to change in load, our mathematical models of the ENDO and EPI cells were used. Our major findings are the following. Our results show that ENDO and EPI cardiomyocytes have different mechanical responses to changes in preload to the cells. Under auxotonic contractions at low preload (unstretched cells), time to peak contraction (Tmax) and the time constant of [Ca2+]i transient decay were significantly longer in ENDO cells than in EPI cells. An increase in preload (stretched cells) prolonged Tmax in both cell types; however, the prolongation was greater in EPI cells, resulting in a decrease in the transmural gradient in Tmax at high preload. Comparing unloaded and heavy loaded (isometric) contractions of the cells we found that transmural gradient in the time course of contraction is independent of the loading conditions. Our mathematical cell models were able to reproduce the experimental results on the distinct cellular responses to changes in the mechanical load when we accounted for an ENDO/EPI difference in the parameters of cooperativity of calcium activation of myofilaments.
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Affiliation(s)
- Anastasia Khokhlova
- Ural Federal University, Mira 19, 620002 Ekaterinburg, Russia; Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Ekaterinburg, Russia.
| | - Gentaro Iribe
- Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Shikata cho 2-5-1, 1700-8558 Okayama, Japan
| | - Leonid Katsnelson
- Ural Federal University, Mira 19, 620002 Ekaterinburg, Russia; Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Ekaterinburg, Russia
| | - Keiji Naruse
- Okayama University, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Shikata cho 2-5-1, 1700-8558 Okayama, Japan
| | - Olga Solovyova
- Ural Federal University, Mira 19, 620002 Ekaterinburg, Russia; Institute of Immunology and Physiology, Russian Academy of Sciences, Pervomajskaya 106, 620049 Ekaterinburg, Russia; Institute of Mathematics and Mechanics, Russian Academy of Sciences, Kovalevskaya 16, 620990 Ekaterinburg, Russia
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