1
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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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Lewalle A, Milburn G, Campbell KS, Niederer SA. Cardiac length-dependent activation driven by force-dependent thick-filament dynamics. Biophys J 2024:S0006-3495(24)00352-7. [PMID: 38807364 DOI: 10.1016/j.bpj.2024.05.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Revised: 04/17/2024] [Accepted: 05/23/2024] [Indexed: 05/30/2024] Open
Abstract
The length-dependent activation (LDA) of maximum force and calcium sensitivity are established features of cardiac muscle contraction but the dominant underlying mechanisms remain to be fully clarified. Alongside the well-documented regulation of contraction via the thin filaments, experiments have identified an additional force-dependent thick-filament activation, whereby myosin heads parked in a so-called off state become available to generate force. This process produces a feedback effect that may potentially drive LDA. Using biomechanical modeling of a human left-ventricular myocyte, this study investigates the extent to which the off-state dynamics could, by itself, plausibly account for LDA, depending on the specific mathematical formulation of the feedback. We hypothesized four different models of the off-state regulatory feedback based on (A) total force, (B) active force, (C) sarcomere strain, and (D) passive force. We tested if these models could reproduce the isometric steady-state and dynamic LDA features predicted by an earlier published model of a human left-ventricle myocyte featuring purely phenomenological length dependences. The results suggest that only total-force feedback (A) is capable of reproducing the expected behaviors, but that passive tension could provide a length-dependent signal on which to initiate the feedback. Furthermore, by attributing LDA to off-state dynamics, our proposed model also qualitatively reproduces experimentally observed effects of the off-state-stabilizing drug mavacamten. Taken together, these results support off-state dynamics as a plausible primary mechanism underlying LDA.
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Affiliation(s)
- Alexandre Lewalle
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, United Kingdom.
| | - Gregory Milburn
- Department of Physiology, University of Kentucky, Lexington, Kentucky
| | - Kenneth S Campbell
- Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky
| | - Steven A Niederer
- National Heart and Lung Institute, Faculty of Medicine, Imperial College London, London, United Kingdom
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3
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Tanner BCW, Palmer BM, Chung CS. Strain rate of stretch affects crossbridge detachment during relaxation of intact cardiac trabeculae. PLoS One 2024; 19:e0297212. [PMID: 38437198 PMCID: PMC10911597 DOI: 10.1371/journal.pone.0297212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 12/29/2023] [Indexed: 03/06/2024] Open
Abstract
Mechanical Control of Relaxation refers to the dependence of myocardial relaxation on the strain rate just prior to relaxation, but the mechanisms of enhanced relaxation are not well characterized. This study aimed to characterize how crossbridge kinetics varied with strain rate and time-to-stretch as the myocardium relaxed in early diastole. Ramp-stretches of varying rates (amplitude = 1% muscle length) were applied to intact rat cardiac trabeculae following a load-clamp at 50% of the maximal developed twitch force, which provides a first-order estimate of ejection and coupling to an afterload. The resultant stress-response was calculated as the difference between the time-dependent stress profile between load-clamped twitches with and without a ramp-stretch. The stress-response exhibited features of the step-stretch response of activated, permeabilized myocardium, such as distortion-dependent peak stress, rapid force decay related to crossbridge detachment, and stress recovery related to crossbridge recruitment. The peak stress was strain rate dependent, but the minimum stress and the time-to-minimum stress values were not. The initial rapid change in the stress-response indicates enhanced crossbridge detachment at higher strain rates during relaxation in intact cardiac trabeculae. Physiologic considerations, such as time-varying calcium, are discussed as potential limitations to fitting these data with traditional distortion-recruitment models of crossbridge activity.
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Affiliation(s)
- Bertrand C. W. Tanner
- Department of Integrative Physiology and Neuroscience, Washington State University, Pullman, Washington, United States of America
| | - Bradley M. Palmer
- Department of Molecular Physiology and Biophysics, University of Vermont, Burlington, Vermont, United States of America
| | - Charles S. Chung
- Department of Physiology, Wayne State University, Detroit, Michigan, United States of America
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4
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Kurihara S, Fukuda N. Regulation of myocardial contraction as revealed by intracellular Ca 2+ measurements using aequorin. J Physiol Sci 2024; 74:12. [PMID: 38383293 PMCID: PMC10882819 DOI: 10.1186/s12576-024-00906-7] [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: 07/25/2023] [Accepted: 02/06/2024] [Indexed: 02/23/2024]
Abstract
Of the ions involved in myocardial function, Ca2+ is the most important. Ca2+ is crucial to the process that allows myocardium to repeatedly contract and relax in a well-organized fashion; it is the process called excitation-contraction coupling. In order, therefore, for accurate comprehension of the physiology of the heart, it is fundamentally important to understand the detailed mechanism by which the intracellular Ca2+ concentration is regulated to elicit excitation-contraction coupling. Aequorin was discovered by Shimomura, Johnson and Saiga in 1962. By taking advantage of the fact that aequorin emits blue light when it binds to Ca2+ within the physiologically relevant concentration range, in the 1970s and 1980s, physiologists microinjected it into myocardial preparations. By doing so, they proved that Ca2+ transients occur upon membrane depolarization, and tension development (i.e., actomyosin interaction) subsequently follows, dramatically advancing the research on cardiac excitation-contraction coupling.
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Affiliation(s)
- Satoshi Kurihara
- Department of Cell Physiology, The Jikei University School of Medicine, 3-25-8 Nishi-Shimbashi, Minato-Ku, Tokyo, 105-8461, Japan.
| | - Norio Fukuda
- Department of Cell Physiology, The Jikei University School of Medicine, 3-25-8 Nishi-Shimbashi, Minato-Ku, Tokyo, 105-8461, Japan
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5
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Lisin R, Balakin A, Mukhlynina E, Protsenko Y. Differences in Mechanical, Electrical and Calcium Transient Performance of the Isolated Right Atrial and Ventricular Myocardium of Guinea Pigs at Different Preloads (Lengths). Int J Mol Sci 2023; 24:15524. [PMID: 37958508 PMCID: PMC10650485 DOI: 10.3390/ijms242115524] [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: 09/29/2023] [Revised: 10/19/2023] [Accepted: 10/22/2023] [Indexed: 11/15/2023] Open
Abstract
There are only a few studies devoted to the comparative and simultaneous study of the mechanisms of the length-dependent regulation of atrial and ventricular contractility. Therefore, an isometric force-length protocol was applied to isolated guinea pig right atrial (RA) strips and ventricular (RV) trabeculae, with a simultaneous measurement of force (Frank-Starling mechanism) and Ca2+ transients (CaT) or transmembrane action potentials (AP). Over the entire length-range studied, the duration of isometric contraction, CaT and AP, were shorter in the RA myocardium than in the RV myocardium. The RA myocardium was stiffer than the RV myocardium. With the increasing length of the RA and RV myocardium, the amplitude and duration of isometric contraction and CaT increased, as well as the amplitude and area of the "CaT difference curves" (shown for the first time). However, the rates of the tension development and relaxation decreased. No contribution of AP duration to the heterometric regulation of isometric tension was found in either the RA or RV myocardium of the guinea pig. Changes in the degree of overlap of the contractile proteins of the guinea pig RA and RV myocardium mainly affect CaT kinetics but not AP duration.
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Affiliation(s)
| | - Alexandr Balakin
- Institute of Immunology and Physiology, Ural Branch of Russian Academy of Sciences, 106 Pervomayskaya Str., Yekaterinburg 620049, Russia; (R.L.); (E.M.); (Y.P.)
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6
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Eisner D, Neher E, Taschenberger H, Smith G. Physiology of intracellular calcium buffering. Physiol Rev 2023; 103:2767-2845. [PMID: 37326298 DOI: 10.1152/physrev.00042.2022] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/08/2023] [Accepted: 06/11/2023] [Indexed: 06/17/2023] Open
Abstract
Calcium signaling underlies much of physiology. Almost all the Ca2+ in the cytoplasm is bound to buffers, with typically only ∼1% being freely ionized at resting levels in most cells. Physiological Ca2+ buffers include small molecules and proteins, and experimentally Ca2+ indicators will also buffer calcium. The chemistry of interactions between Ca2+ and buffers determines the extent and speed of Ca2+ binding. The physiological effects of Ca2+ buffers are determined by the kinetics with which they bind Ca2+ and their mobility within the cell. The degree of buffering depends on factors such as the affinity for Ca2+, the Ca2+ concentration, and whether Ca2+ ions bind cooperatively. Buffering affects both the amplitude and time course of cytoplasmic Ca2+ signals as well as changes of Ca2+ concentration in organelles. It can also facilitate Ca2+ diffusion inside the cell. Ca2+ buffering affects synaptic transmission, muscle contraction, Ca2+ transport across epithelia, and the killing of bacteria. Saturation of buffers leads to synaptic facilitation and tetanic contraction in skeletal muscle and may play a role in inotropy in the heart. This review focuses on the link between buffer chemistry and function and how Ca2+ buffering affects normal physiology and the consequences of changes in disease. As well as summarizing what is known, we point out the many areas where further work is required.
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Affiliation(s)
- David Eisner
- Division of Cardiovascular Sciences, University of Manchester, Manchester, United Kingdom
| | - Erwin Neher
- Membrane Biophysics Laboratory, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC), University of Göttingen, Göttingen, Germany
| | - Holger Taschenberger
- Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Godfrey Smith
- School of Cardiovascular and Metabolic Health, College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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7
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Strocchi M, Longobardi S, Augustin CM, Gsell MAF, Petras A, Rinaldi CA, Vigmond EJ, Plank G, Oates CJ, Wilkinson RD, Niederer SA. Cell to whole organ global sensitivity analysis on a four-chamber heart electromechanics model using Gaussian processes emulators. PLoS Comput Biol 2023; 19:e1011257. [PMID: 37363928 DOI: 10.1371/journal.pcbi.1011257] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 06/09/2023] [Indexed: 06/28/2023] Open
Abstract
Cardiac pump function arises from a series of highly orchestrated events across multiple scales. Computational electromechanics can encode these events in physics-constrained models. However, the large number of parameters in these models has made the systematic study of the link between cellular, tissue, and organ scale parameters to whole heart physiology challenging. A patient-specific anatomical heart model, or digital twin, was created. Cellular ionic dynamics and contraction were simulated with the Courtemanche-Land and the ToR-ORd-Land models for the atria and the ventricles, respectively. Whole heart contraction was coupled with the circulatory system, simulated with CircAdapt, while accounting for the effect of the pericardium on cardiac motion. The four-chamber electromechanics framework resulted in 117 parameters of interest. The model was broken into five hierarchical sub-models: tissue electrophysiology, ToR-ORd-Land model, Courtemanche-Land model, passive mechanics and CircAdapt. For each sub-model, we trained Gaussian processes emulators (GPEs) that were then used to perform a global sensitivity analysis (GSA) to retain parameters explaining 90% of the total sensitivity for subsequent analysis. We identified 45 out of 117 parameters that were important for whole heart function. We performed a GSA over these 45 parameters and identified the systemic and pulmonary peripheral resistance as being critical parameters for a wide range of volumetric and hemodynamic cardiac indexes across all four chambers. We have shown that GPEs provide a robust method for mapping between cellular properties and clinical measurements. This could be applied to identify parameters that can be calibrated in patient-specific models or digital twins, and to link cellular function to clinical indexes.
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Affiliation(s)
- Marina Strocchi
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
| | - Stefano Longobardi
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
| | | | | | - Argyrios Petras
- Johann Radon Institute for Computational and Applied Mathematics (RICAM), Linz, Austria
| | - Christopher A Rinaldi
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - Edward J Vigmond
- University of Bordeaux, CNRS, Bordeaux, Talence, France
- IHU Liryc, Bordeaux, Talence, France
| | - Gernot Plank
- Medical University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Chris J Oates
- Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Steven A Niederer
- School of Biomedical Engineering and Imaging Sciences, King's College London, London, United Kingdom
- National Heart and Lung Institute, Imperial College London, London, United Kingdom
- Alan Turing Institute, London, United Kingdom
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8
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Feng HZ, Huang X, Jin JP. N-terminal truncated cardiac troponin I enhances Frank-Starling response by increasing myofilament sensitivity to resting tension. J Gen Physiol 2023; 155:e202012821. [PMID: 36880803 PMCID: PMC10005897 DOI: 10.1085/jgp.202012821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 12/09/2022] [Accepted: 12/29/2022] [Indexed: 03/08/2023] Open
Abstract
Cardiac troponin I (cTnI) of higher vertebrates has evolved with an N-terminal extension, of which deletion via restrictive proteolysis occurs as a compensatory adaptation in chronic heart failure to increase ventricular relaxation and stroke volume. Here, we demonstrate in a transgenic mouse model expressing solely N-terminal truncated cTnI (cTnI-ND) in the heart with deletion of the endogenous cTnI gene. Functional studies using ex vivo working hearts showed an extended Frank-Starling response to preload with reduced left ventricular end diastolic pressure. The enhanced Frank-Starling response effectively increases systolic ventricular pressure development and stroke volume. A novel finding is that cTnI-ND increases left ventricular relaxation velocity and stroke volume without increasing the end diastolic volume. Consistently, the optimal resting sarcomere length (SL) for maximum force development in cTnI-ND cardiac muscle was not different from wild-type (WT) control. Despite the removal of the protein kinase A (PKA) phosphorylation sites in cTnI, β-adrenergic stimulation remains effective on augmenting the enhanced Frank-Starling response of cTnI-ND hearts. Force-pCa relationship studies using skinned preparations found that while cTnI-ND cardiac muscle shows a resting SL-resting tension relationship similar to WT control, cTnI-ND significantly increases myofibril Ca2+ sensitivity to resting tension. The results demonstrate that restrictive N-terminal deletion of cTnI enhances Frank-Starling response by increasing myofilament sensitivity to resting tension rather than directly depending on SL. This novel function of cTnI regulation suggests a myofilament approach to utilizing Frank-Starling mechanism for the treatment of heart failure, especially diastolic failure where ventricular filling is limited.
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Affiliation(s)
- Han-Zhong Feng
- Department of Physiology and Biophysics, University of Illinois at Chicago School of Medicine, Chicago, IL, USA
| | - Xupei Huang
- Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL, USA
| | - Jian-Ping Jin
- Department of Physiology and Biophysics, University of Illinois at Chicago School of Medicine, Chicago, IL, USA
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9
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Tanner BCW, Awinda PO, Agonias KB, Attili S, Blair CA, Thompson MS, Walker LA, Kampourakis T, Campbell KS. Sarcomere length affects Ca2+ sensitivity of contraction in ischemic but not non-ischemic myocardium. J Gen Physiol 2023; 155:213800. [PMID: 36633584 PMCID: PMC9859763 DOI: 10.1085/jgp.202213200] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 11/18/2022] [Accepted: 12/22/2022] [Indexed: 01/13/2023] Open
Abstract
In healthy hearts, myofilaments become more sensitive to Ca2+ as the myocardium is stretched. This effect is known as length-dependent activation and is an important cellular-level component of the Frank-Starling mechanism. Few studies have measured length-dependent activation in the myocardium from failing human hearts. We investigated whether ischemic and non-ischemic heart failure results in different length-dependent activation responses at physiological temperature (37°C). Myocardial strips from the left ventricular free wall were chemically permeabilized and Ca2+-activated at sarcomere lengths (SLs) of 1.9 and 2.3 µm. Data were acquired from 12 hearts that were explanted from patients receiving cardiac transplants; 6 had ischemic heart failure and 6 had non-ischemic heart failure. Another 6 hearts were obtained from organ donors. Maximal Ca2+-activated force increased at longer SL for all groups. Ca2+ sensitivity increased with SL in samples from donors (P < 0.001) and patients with ischemic heart failure (P = 0.003) but did not change with SL in samples from patients with non-ischemic heart failure. Compared with donors, troponin I phosphorylation decreased in ischemic samples and even more so in non-ischemic samples; cardiac myosin binding protein-C (cMyBP-C) phosphorylation also decreased with heart failure. These findings support the idea that troponin I and cMyBP-C phosphorylation promote length-dependent activation and show that length-dependent activation of contraction is blunted, yet extant, in the myocardium from patients with ischemic heart failure and further reduced in the myocardium from patients with non-ischemic heart failure. Patients who have a non-ischemic disease may exhibit a diminished contractile response to increased ventricular filling.
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Affiliation(s)
- Bertrand C W Tanner
- Department of Integrative Physiology and Neuroscience, Washington State University , Pullman, WA, USA
| | - Peter O Awinda
- Department of Integrative Physiology and Neuroscience, Washington State University , Pullman, WA, USA
| | - Keinan B Agonias
- Department of Integrative Physiology and Neuroscience, Washington State University , Pullman, WA, USA
| | - Seetharamaiah Attili
- Randall Centre for Cell and Molecular Biophysics, King's College London , London, UK
| | - Cheavar A Blair
- Department of Physiology, University of Kentucky , Lexington, KY, USA
| | - Mindy S Thompson
- Department of Physiology, University of Kentucky , Lexington, KY, USA
| | - Lori A Walker
- Division of Cardiology, Department of Medicine, University of Colorado Anschutz Medical Campus , Aurora, CO, USA
| | - Thomas Kampourakis
- Randall Centre for Cell and Molecular Biophysics, King's College London , London, UK
| | - Kenneth S Campbell
- Department of Physiology, University of Kentucky , Lexington, KY, USA.,Division of Cardiovascular Medicine, University of Kentucky , Lexington, KY, USA
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10
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Kimmig F, Caruel M, Chapelle D. Varying thin filament activation in the framework of the Huxley'57 model. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2022; 38:e3655. [PMID: 36210493 DOI: 10.1002/cnm.3655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 04/29/2022] [Accepted: 09/24/2022] [Indexed: 06/16/2023]
Abstract
Muscle contraction is triggered by the activation of the actin sites of the thin filament by calcium ions. It results that the thin filament activation level varies over time. Moreover, this activation process is also used as a regulation mechanism of the developed force. Our objective is to build a model of varying actin site activation level within the classical Huxley'57 two-state framework. This new model is obtained as an enhancement of a previously proposed formulation of the varying thick filament activation within the same framework. We assume that the state of an actin site depends on whether it is activated and whether it forms a cross-bridge with the associated myosin head, which results in four possible states. The transitions between the actin site states are controlled by the global actin sites activation level and the dynamics of these transitions is coupled with the attachment-detachment process. A preliminary calibration of the model with experimental twitch contraction data obtained at varying sarcomere lengths is performed.
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Affiliation(s)
- François Kimmig
- LMS, École Polytechnique, CNRS, Institut Polytechnique de Paris, Palaiseau, France
- Inria, Palaiseau, France
| | - Matthieu Caruel
- CNRS, UMR 8208, MSME, Univ Paris Est Creteil, Univ Gustave Eiffel, Créteil, France
| | - Dominique Chapelle
- LMS, École Polytechnique, CNRS, Institut Polytechnique de Paris, Palaiseau, France
- Inria, Palaiseau, France
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11
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Lookin O, Protsenko Y. The Slow Force Response and Simultaneous Changes in Ca2+ Transient in Healthy and Failing Rat Atrial and Ventricular Myocardium. J EVOL BIOCHEM PHYS+ 2022. [DOI: 10.1134/s0022093022070043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
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12
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Post-gastrulation transition from whole-body to tissue-specific intercellular calcium signaling in the appendicularian tunicate Oikopleuradioica. Dev Biol 2022; 492:37-46. [PMID: 36162551 DOI: 10.1016/j.ydbio.2022.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 07/09/2022] [Accepted: 09/17/2022] [Indexed: 11/21/2022]
Abstract
We recently described calcium signaling in the appendicularian tunicate Oikopleura dioica during pre-gastrulation stages, and showed that regularly occurring calcium waves progress throughout the embryo in a characteristic spatiotemporal pattern from an initiation site in muscle lineage blastomeres (Mikhaleva et al., 2019). Here, we have extended our observations to the period spanning from gastrulation to post-hatching stages. We find that repetitive Ca2+ waves persist throughout this developmental window, albeit with a gradual increase in frequency. The initiation site of the waves shifts from muscle cells at gastrulation and early tailbud stages, to the central nervous system at late tailbud and post-hatching stages, indicating a transition from muscle-driven to neurally driven events as tail movements emerge. At these later stages, both the voltage gated Na + channel blocker tetrodotoxin (TTX) and the T-type Ca2+ channel blocker and nAChR antagonist mecamylamine eliminate tail movements. At late post-hatching stages, mecamylamine blocks Ca2+ signals in the muscles but not the central nervous system. Post-gastrulation Ca2+ signals also arise in epithelial cells, first in a haphazard pattern in scattered cells during tailbud stages, evolving after hatching into repetitive rostrocaudal waves with a different frequency than the nervous system-to-muscle waves, and insensitive to mecamylamine. The desynchronization of Ca2+ waves arising in different parts of the body indicates a shift from whole-body to tissue/organ-specific Ca2+ signaling dynamics as organogenesis occurs, with neurally driven Ca2+ signaling dominating at the later stages when behavior emerges.
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13
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Zechini L, Camilleri-Brennan J, Walsh J, Beaven R, Moran O, Hartley PS, Diaz M, Denholm B. Piezo buffers mechanical stress via modulation of intracellular Ca 2+ handling in the Drosophila heart. Front Physiol 2022; 13:1003999. [PMID: 36187790 PMCID: PMC9515499 DOI: 10.3389/fphys.2022.1003999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 08/26/2022] [Indexed: 11/13/2022] Open
Abstract
Throughout its lifetime the heart is buffeted continuously by dynamic mechanical forces resulting from contraction of the heart muscle itself and fluctuations in haemodynamic load and pressure. These forces are in flux on a beat-by-beat basis, resulting from changes in posture, physical activity or emotional state, and over longer timescales due to altered physiology (e.g. pregnancy) or as a consequence of ageing or disease (e.g. hypertension). It has been known for over a century of the heart's ability to sense differences in haemodynamic load and adjust contractile force accordingly (Frank, Z. biology, 1895, 32, 370-447; Anrep, J. Physiol., 1912, 45 (5), 307-317; Patterson and Starling, J. Physiol., 1914, 48 (5), 357-79; Starling, The law of the heart (Linacre Lecture, given at Cambridge, 1915), 1918). These adaptive behaviours are important for cardiovascular homeostasis, but the mechanism(s) underpinning them are incompletely understood. Here we present evidence that the mechanically-activated ion channel, Piezo, is an important component of the Drosophila heart's ability to adapt to mechanical force. We find Piezo is a sarcoplasmic reticulum (SR)-resident channel and is part of a mechanism that regulates Ca2+ handling in cardiomyocytes in response to mechanical stress. Our data support a simple model in which Drosophila Piezo transduces mechanical force such as stretch into a Ca2+ signal, originating from the SR, that modulates cardiomyocyte contraction. We show that Piezo mutant hearts fail to buffer mechanical stress, have altered Ca2+ handling, become prone to arrhythmias and undergo pathological remodelling.
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Affiliation(s)
- Luigi Zechini
- Deanery of Biomedical Sciences, Edinburgh Medical School, Edinburgh University, Edinburgh, United Kingtom
- Centre for Inflammation Research, Deanery of Clinical Sciences, Edinburgh Medical School, Edinburgh, United Kingtom
| | - Julian Camilleri-Brennan
- Deanery of Biomedical Sciences, Edinburgh Medical School, Edinburgh University, Edinburgh, United Kingtom
| | - Jonathan Walsh
- Deanery of Biomedical Sciences, Edinburgh Medical School, Edinburgh University, Edinburgh, United Kingtom
| | - Robin Beaven
- Deanery of Biomedical Sciences, Edinburgh Medical School, Edinburgh University, Edinburgh, United Kingtom
| | - Oscar Moran
- Istituto di Biofisica, Consiglio Nazionale delle Ricerche- CNR, Genoa, Italy
| | - Paul S. Hartley
- Department of Life and Environmental Science, Faculty of Science and Technology, Bournemouth University, Poole, United Kingtom
| | - Mary Diaz
- Deanery of Biomedical Sciences, Edinburgh Medical School, Edinburgh University, Edinburgh, United Kingtom
| | - Barry Denholm
- Deanery of Biomedical Sciences, Edinburgh Medical School, Edinburgh University, Edinburgh, United Kingtom
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14
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Dowrick JM, Tran K, Garrett AS, Anderson AJ, Nielsen PMF, Taberner AJ, Han JC. Work-loop contractions reveal that the afterload-dependent time course of cardiac Ca 2+ transients is modulated by preload. J Appl Physiol (1985) 2022; 133:663-675. [PMID: 35771221 PMCID: PMC9762964 DOI: 10.1152/japplphysiol.00137.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Preload and afterload dictate the dynamics of the cyclical work-loop contraction that the heart undergoes in vivo. Cellular Ca2+ dynamics drive contraction, but the effects of afterload alone on the Ca2+ transient are inconclusive. To our knowledge, no study has investigated whether the putative afterload dependence of the Ca2+ transient is preload dependent. This study is designed to provide the first insight into the Ca2+ handling of cardiac trabeculae undergoing work-loop contractions, with the aim to examine whether the conflicting afterload dependency of the Ca2+ transient can be accounted for by considering preload under isometric and physiological work-loop contractions. Thus, we subjected ex vivo rat right-ventricular trabeculae, loaded with the fluorescent dye Fura-2, to work-loop contractions over a wide range of afterloads at two preloads while measuring stress, length changes, and Ca2+ transients. Work-loop control was implemented with a real-time Windkessel model to mimic the contraction patterns of the heart in vivo. We extracted a range of metrics from the measured steady-state twitch stress and Ca2+ transients, including the amplitudes, time courses, rates of rise, and integrals. Results show that parameters of stress were afterload and preload dependent. In contrast, the parameters associated with Ca2+ transients displayed a mixed dependence on afterload and preload. Most notably, its time course was afterload dependent, an effect augmented at the greater preload. This study reveals that the afterload dependence of cardiac Ca2+ transients is modulated by preload, which brings the study of Ca2+ transients during isometric contractions into question when aiming to understand physiological Ca2+ handling.NEW & NOTEWORTHY This study is the first examination of Ca2+ handling in trabeculae undergoing work-loop contractions. These data reveal that reducing preload diminishes the influence of afterload on the decay phase of the cardiac Ca2+ transient. This is significant as it reconciles inconsistencies in the literature regarding the influence of external loads on cardiac Ca2+ handling. Furthermore, these findings highlight discrepancies between Ca2+ handling during isometric and work-loop contractions in cardiac trabeculae operating at their optimal length.
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Affiliation(s)
- Jarrah M. Dowrick
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Kenneth Tran
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Amy S. Garrett
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Alex J. Anderson
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Poul M. F. Nielsen
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand,2Department of Engineering Science, University of Auckland, Auckland, New Zealand
| | - Andrew J. Taberner
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand,2Department of Engineering Science, University of Auckland, Auckland, New Zealand
| | - June-Chiew Han
- 1Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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15
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Yamada T, Ashida Y, Tamai K, Kimura I, Yamauchi N, Naito A, Tokuda N, Westerblad H, Andersson DC, Himori K. Improved skeletal muscle fatigue resistance in experimental autoimmune myositis mice following high-intensity interval training. Arthritis Res Ther 2022; 24:156. [PMID: 35761371 PMCID: PMC9235155 DOI: 10.1186/s13075-022-02846-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 06/18/2022] [Indexed: 12/03/2022] Open
Abstract
Background Muscle weakness and decreased fatigue resistance are key manifestations of systemic autoimmune myopathies (SAMs). We here examined whether high-intensity interval training (HIIT) improves fatigue resistance in the skeletal muscle of experimental autoimmune myositis (EAM) mice, a widely used animal model for SAM. Methods Female BALB/c mice were randomly assigned to control (CNT) or EAM groups (n = 28 in each group). EAM was induced by immunization with three injections of myosin emulsified in complete Freund’s adjuvant. The plantar flexor (PF) muscles of mice with EAM were exposed to either an acute bout or 4 weeks of HIIT (a total of 14 sessions). Results The fatigue resistance of PF muscles was lower in the EAM than in the CNT group (P < 0.05). These changes were associated with decreased activities of citrate synthase and cytochrome c oxidase and increased expression levels of the endoplasmic reticulum stress proteins (glucose-regulated protein 78 and 94, and PKR-like ER kinase) (P < 0.05). HIIT restored all these alterations and increased the peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and the mitochondrial electron transport chain complexes (I, III, and IV) in the muscles of EAM mice (P < 0.05). Conclusions HIIT improves fatigue resistance in a SAM mouse model, and this can be explained by the restoration of mitochondria oxidative capacity via inhibition of the ER stress pathway and PGC-1α-mediated mitochondrial biogenesis.
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Fu F, Guo L, Tang X, Wang J, Xie Z, Fekete G, Cai Y, Hu Q, Gu Y. Effect of the Innovative Running Shoes With the Special Midsole Structure on the Female Runners’ Lower Limb Biomechanics. Front Bioeng Biotechnol 2022; 10:866321. [PMID: 35733527 PMCID: PMC9208082 DOI: 10.3389/fbioe.2022.866321] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 04/27/2022] [Indexed: 11/21/2022] Open
Abstract
The study aimed to research the effects of innovative running shoes (a high heel-to-toe drop and special structure of midsole) on the biomechanics of the lower limbs and perceptual sensitivity in female runners. Fifteen healthy female runners were recruited to run through a 145-m runway with planted force plates at one peculiar speed (3.6 m/s ± 5%) with two kinds of shoe conditions (innovative running shoes vs. normal running shoes) while getting biomechanical data. The perception of shoe characteristics was assessed simultaneously through a 15-cm visual analog scale. The statistical parametric mapping technique calculated the time-series parameters. Regarding 0D parameters, the ankle dorsiflexion angle of innovative running shoes at touchdown was higher, and the peak dorsiflexion angle, range of motion, peak dorsiflexion velocity, and plantarflexion moment on the metatarsophalangeal joint of innovative running shoes during running were significantly smaller than those of normal running shoes (all p < 0.001). In addition, the braking phase and the time of peak vertical force 1 of innovative running shoes were found to be longer than those of normal running shoes (both p < 0.05). Meanwhile, the average vertical loading rate 1, peak vertical loading rate 1, peak braking force, and peak vertical force 1 in the innovative running shoes were lower than those of the normal running shoes during running (both p < 0.01). The statistical parametric mapping analysis exhibited a higher ankle dorsiflexion angle (0–4%, p < 0.05), a smaller knee internal rotation angle (0–6%, p < 0.05) (63–72%, p < 0.05), a decreased vertical ground reaction force (11–17%, p = 0.009), and braking anteroposterior ground reaction force (22–27%, p = 0.043) for innovative running shoes than normal running shoes. Runners were able to perceive the cushioning of innovative running shoes was better than that of normal running shoes. These findings suggested combining the high offset and structure of the midsole would benefit the industrial utilization of shoe producers in light of reducing the risk of running injuries for female runners.
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Affiliation(s)
- Fengqin Fu
- Faculty of Sports Science, Ningbo University, Ningbo, China
- Doctoral School on Safety and Security Sciences, Óbuda University, Budapest, Hungary
- Science Laboratory, Innovation center of Xtep Co., Ltd., Xiamen, China
| | - Lianming Guo
- Science Laboratory, Innovation center of Xtep Co., Ltd., Xiamen, China
| | - Xunfei Tang
- Science Laboratory, Innovation center of Xtep Co., Ltd., Xiamen, China
| | - Jiayu Wang
- Faculty of Sports Science, Ningbo University, Ningbo, China
| | - Zhihao Xie
- Science Laboratory, Innovation center of Xtep Co., Ltd., Xiamen, China
| | - Gusztáv Fekete
- Savaria Institute of Technology, Eötvös Loránd University, Budapest, Hungary
| | - Yuhui Cai
- Science Laboratory, Innovation center of Xtep Co., Ltd., Xiamen, China
| | - Qiuli Hu
- Faculty of Sports Science, Ningbo University, Ningbo, China
| | - Yaodong Gu
- Faculty of Sports Science, Ningbo University, Ningbo, China
- *Correspondence: Yaodong Gu,
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17
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Zero AM, Rice CL. Post-activation potentiation induced by concentric contractions at three speeds in humans. Exp Physiol 2021; 106:2489-2501. [PMID: 34569107 DOI: 10.1113/ep089613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 09/23/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Is the degree of in human muscle affected by different shortening velocities, or contraction type? What are the main findings and their importance? The PAP response following maximal concentric contractions was independent of velocity. Slow and moderate velocity maximal contractions produced PAP responses like those from maximal isometric contractions when matched for contraction duration. Despite contraction type differences in cross-bridge and Ca2+ kinetics, maximal contractions, regardless of contraction modality, likely generate sufficient Ca2+ to induce maximal PAP. ABSTRACT Post-activation potentiation (PAP) is the acute enhancement of contractile properties following a brief (<10 s) high-intensity contraction. Compared with isometric contractions, little is known about the PAP response induced by concentric conditioning contractions (CCs) and the effect of velocity. In the dorsiflexors of 11 participants, twitch responses were measured following 5 s of maximal effort concentric CCs at each of 10, 20 and 50°/s. Concentric PAP responses were compared to a maximal isometric voluntary contraction (MVC) matched for contraction time. Additionally, concentric CCs were compared to isometric CCs matched for mean torque, contraction area and time. The PAP response following maximal concentric CCs was independent of velocity and there was no difference in the PAP response between concentric CCs and an isometric MVC. During maximal contractions, regardless of contraction modality, there is likely sufficient Ca2+ to induce a similar full PAP response, and thus there was no difference between speeds or contraction type. Following concentric CCs there was a significantly larger peak twitch torque than following their isometric torque matches (49-58%), and faster maximal rates of torque development at the three speeds (62-77%). However, these responses are likely related to greater EMG in concentric contractions, 125-129% of isometric maximum compared to 38-54%, and not to contraction modality per se. Thus, PAP responses following maximal concentric CCs are not affected by velocity and responses are not different from an isometric MVC. This indicates maximal CCs of 5 s produce a maximal PAP response independent of contraction type (isometric vs. concentric) or shortening velocity.
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Affiliation(s)
- Alexander M Zero
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada
| | - Charles L Rice
- School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada.,Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada
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18
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Fu F, Levadnyi I, Wang J, Xie Z, Fekete G, Cai Y, Gu Y. Effect of the Construction of Carbon Fiber Plate Insert to Midsole on Running Performance. MATERIALS 2021; 14:ma14185156. [PMID: 34576379 PMCID: PMC8467156 DOI: 10.3390/ma14185156] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 08/26/2021] [Accepted: 08/30/2021] [Indexed: 11/16/2022]
Abstract
In this paper, to investigate the independent effect of the construction of the forefoot carbon-fiber plate inserted to the midsole on running biomechanics and finite element simulation, fifteen male marathon runners were arranged to run across a runway with embedded force plates at two specific running speeds (fast-speed: 4.81 ± 0.32 m/s, slow-speed: 3.97 ± 0.19 m/s) with two different experimental shoes (a segmented forefoot plate construction (SFC), and a full forefoot plate construction (FFC)), simulating the different pressure distributions, energy return, and stiffness during bending in the forefoot region between the SFC and FFC inserted to midsole. Kinetics and joint mechanics were analyzed. The results showed that the footwear with SFC significantly increased the peak metatarsophalangeal joint (MTPJ) plantarflexion velocity and positive work at the knee joint compared to the footwear with FFC. The results about finite element simulation showed a reduced maximum pressure on the midsole; meanwhile, not significantly affected was the longitudinal bending stiffness and energy return with the SFC compared to the FFC. The results can be used for the design of marathon running shoes, because changing the full carbon fiber plate to segment carbon fiber plate induced some biomechanical transformation but did not significantly affect the running performance, what is more, reducing the peak pressure of the carbon plate to the midsole by cutting the forefoot area of the carbon fiber plate could be beneficial from a long-distance running perspective for manufacturers.
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Affiliation(s)
- Fengqin Fu
- Faculty of Sports Science, Ningbo University, Ningbo 315000, China; (F.F.); (J.W.)
- Doctoral School on Safety and Security Sciences, Óbuda University, 1011-1239 Budapest, Hungary
- Xtep Sports Science & Engineering Laboratory, Xtep Co. Ltd., Xiamen 361000, China; (I.L.); (Z.X.); (Y.C.)
| | - Ievgen Levadnyi
- Xtep Sports Science & Engineering Laboratory, Xtep Co. Ltd., Xiamen 361000, China; (I.L.); (Z.X.); (Y.C.)
| | - Jiayu Wang
- Faculty of Sports Science, Ningbo University, Ningbo 315000, China; (F.F.); (J.W.)
| | - Zhihao Xie
- Xtep Sports Science & Engineering Laboratory, Xtep Co. Ltd., Xiamen 361000, China; (I.L.); (Z.X.); (Y.C.)
| | - Gusztáv Fekete
- Savaria Institute of Technology, Eötvös Loránd University, 9700 Szombathely, Hungary;
| | - Yuhui Cai
- Xtep Sports Science & Engineering Laboratory, Xtep Co. Ltd., Xiamen 361000, China; (I.L.); (Z.X.); (Y.C.)
| | - Yaodong Gu
- Faculty of Sports Science, Ningbo University, Ningbo 315000, China; (F.F.); (J.W.)
- Correspondence: ; Tel.: +86-574-87600208
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19
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Shim HJ, Sunwoo S, Kim Y, Koo JH, Kim D. Functionalized Elastomers for Intrinsically Soft and Biointegrated Electronics. Adv Healthc Mater 2021; 10:e2002105. [PMID: 33506654 DOI: 10.1002/adhm.202002105] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/31/2020] [Indexed: 12/11/2022]
Abstract
Elastomers are suitable materials for constructing a conformal interface with soft and curvilinear biological tissue due to their intrinsically deformable mechanical properties. Intrinsically soft electronic devices whose mechanical properties are comparable to human tissue can be fabricated using suitably functionalized elastomers. This article reviews recent progress in functionalized elastomers and their application to intrinsically soft and biointegrated electronics. Elastomers can be functionalized by adding appropriate fillers, either nanoscale materials or polymers. Conducting or semiconducting elastomers synthesized and/or processed with these materials can be applied to the fabrication of soft biointegrated electronic devices. For facile integration of soft electronics with the human body, additional functionalization strategies can be employed to improve adhesive or autonomous healing properties. Recently, device components for intrinsically soft and biointegrated electronics, including sensors, stimulators, power supply devices, displays, and transistors, have been developed. Herein, representative examples of these fully elastomeric device components are discussed. Finally, the remaining challenges and future outlooks for the field are presented.
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Affiliation(s)
- Hyung Joon Shim
- Center for Nanoparticle Research Institute for Basic Science (IBS) Seoul 08826 Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes Seoul National University Seoul 08826 Republic of Korea
| | - Sung‐Hyuk Sunwoo
- Center for Nanoparticle Research Institute for Basic Science (IBS) Seoul 08826 Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes Seoul National University Seoul 08826 Republic of Korea
| | - Yeongjun Kim
- Center for Nanoparticle Research Institute for Basic Science (IBS) Seoul 08826 Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes Seoul National University Seoul 08826 Republic of Korea
| | - Ja Hoon Koo
- Center for Nanoparticle Research Institute for Basic Science (IBS) Seoul 08826 Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes Seoul National University Seoul 08826 Republic of Korea
| | - Dae‐Hyeong Kim
- Center for Nanoparticle Research Institute for Basic Science (IBS) Seoul 08826 Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes Seoul National University Seoul 08826 Republic of Korea
- Department of Materials Science and Engineering Seoul National University Seoul 08826 Republic of Korea
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20
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Hanft LM, Fitzsimons DP, Hacker TA, Moss RL, McDonald KS. Cardiac MyBP-C phosphorylation regulates the Frank-Starling relationship in murine hearts. J Gen Physiol 2021; 153:e202012770. [PMID: 33646280 PMCID: PMC7927661 DOI: 10.1085/jgp.202012770] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 01/04/2021] [Accepted: 01/26/2021] [Indexed: 01/08/2023] Open
Abstract
The Frank-Starling relationship establishes that elevated end-diastolic volume progressively increases ventricular pressure and stroke volume in healthy hearts. The relationship is modulated by a number of physiological inputs and is often depressed in human heart failure. Emerging evidence suggests that cardiac myosin-binding protein-C (cMyBP-C) contributes to the Frank-Starling relationship. We measured contractile properties at multiple levels of structural organization to determine the role of cMyBP-C and its phosphorylation in regulating (1) the sarcomere length dependence of power in cardiac myofilaments and (2) the Frank-Starling relationship in vivo. We compared transgenic mice expressing wild-type cMyBP-C on the null background, which have ∼50% phosphorylated cMyBP-C (Controls), to transgenic mice lacking cMyBP-C (KO) and to mice expressing cMyBP-C that have serine-273, -282, and -302 mutated to aspartate (cMyBP-C t3SD) or alanine (cMyBP-C t3SA) on the null background to mimic either constitutive PKA phosphorylation or nonphosphorylated cMyBP-C, respectively. We observed a continuum of length dependence of power output in myocyte preparations. Sarcomere length dependence of power progressively increased with a rank ordering of cMyBP-C KO = cMyBP-C t3SA < Control < cMyBP-C t3SD. Length dependence of myofilament power translated, at least in part, to hearts, whereby Frank-Starling relationships were steepest in cMyBP-C t3SD mice. The results support the hypothesis that cMyBP-C and its phosphorylation state tune sarcomere length dependence of myofibrillar power, and these regulatory processes translate across spatial levels of myocardial organization to control beat-to-beat ventricular performance.
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Affiliation(s)
- Laurin M. Hanft
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
| | - Daniel P. Fitzsimons
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI
| | - Timothy A. Hacker
- Department of Medicine, University of Wisconsin-Madison, Madison, WI
| | - Richard L. Moss
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, WI
| | - Kerry S. McDonald
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO
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21
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Izu L, Shimkunas R, Jian Z, Hegyi B, Kazemi-Lari M, Baker A, Shaw J, Banyasz T, Chen-Izu Y. Emergence of Mechano-Sensitive Contraction Autoregulation in Cardiomyocytes. Life (Basel) 2021; 11:503. [PMID: 34072584 PMCID: PMC8227646 DOI: 10.3390/life11060503] [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: 04/23/2021] [Revised: 05/26/2021] [Accepted: 05/27/2021] [Indexed: 12/24/2022] Open
Abstract
The heart has two intrinsic mechanisms to enhance contractile strength that compensate for increased mechanical load to help maintain cardiac output. When vascular resistance increases the ventricular chamber initially expands causing an immediate length-dependent increase of contraction force via the Frank-Starling mechanism. Additionally, the stress-dependent Anrep effect slowly increases contraction force that results in the recovery of the chamber volume towards its initial state. The Anrep effect poses a paradox: how can the cardiomyocyte maintain higher contractility even after the cell length has recovered its initial length? Here we propose a surface mechanosensor model that enables the cardiomyocyte to sense different mechanical stresses at the same mechanical strain. The cell-surface mechanosensor is coupled to a mechano-chemo-transduction feedback mechanism involving three elements: surface mechanosensor strain, intracellular Ca2+ transient, and cell strain. We show that in this simple yet general system, contractility autoregulation naturally emerges, enabling the cardiomyocyte to maintain contraction amplitude despite changes in a range of afterloads. These nontrivial model predictions have been experimentally confirmed. Hence, this model provides a new conceptual framework for understanding the contractility autoregulation in cardiomyocytes, which contributes to the heart's intrinsic adaptivity to mechanical load changes in health and diseases.
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Affiliation(s)
- Leighton Izu
- Department of Pharmacology, University of California, Davis, CA 95616, USA; (R.S.); (Z.J.); (B.H.); (M.K.-L.); (T.B.); (Y.C.-I.)
| | - Rafael Shimkunas
- Department of Pharmacology, University of California, Davis, CA 95616, USA; (R.S.); (Z.J.); (B.H.); (M.K.-L.); (T.B.); (Y.C.-I.)
| | - Zhong Jian
- Department of Pharmacology, University of California, Davis, CA 95616, USA; (R.S.); (Z.J.); (B.H.); (M.K.-L.); (T.B.); (Y.C.-I.)
| | - Bence Hegyi
- Department of Pharmacology, University of California, Davis, CA 95616, USA; (R.S.); (Z.J.); (B.H.); (M.K.-L.); (T.B.); (Y.C.-I.)
| | - Mohammad Kazemi-Lari
- Department of Pharmacology, University of California, Davis, CA 95616, USA; (R.S.); (Z.J.); (B.H.); (M.K.-L.); (T.B.); (Y.C.-I.)
| | - Anthony Baker
- Department of Medicine, University of California, San Francisco, CA 94121, USA;
| | - John Shaw
- Department of Aerospace Engineering, University of Michigan, Ann Arbor, MI 48109, USA;
| | - Tamas Banyasz
- Department of Pharmacology, University of California, Davis, CA 95616, USA; (R.S.); (Z.J.); (B.H.); (M.K.-L.); (T.B.); (Y.C.-I.)
- Department of Physiology, University of Debrecen, 4032 Debrecen, Hungary
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, CA 95616, USA; (R.S.); (Z.J.); (B.H.); (M.K.-L.); (T.B.); (Y.C.-I.)
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
- Department of Internal Medicine, Division of Cardiology, University of California, Davis, CA 95616, USA
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Limbu S, Prosser BL, Lederer WJ, Ward CW, Jafri MS. X-ROS Signaling Depends on Length-Dependent Calcium Buffering by Troponin. Cells 2021; 10:cells10051189. [PMID: 34068012 PMCID: PMC8152234 DOI: 10.3390/cells10051189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 05/07/2021] [Accepted: 05/08/2021] [Indexed: 12/03/2022] Open
Abstract
The stretching of a cardiomyocyte leads to the increased production of reactive oxygen species that increases ryanodine receptor open probability through a process termed X-ROS signaling. The stretching of the myocyte also increases the calcium affinity of myofilament Troponin C, which increases its calcium buffering capacity. Here, an integrative experimental and modeling study is pursued to explain the interplay of length-dependent changes in calcium buffering by troponin and stretch-activated X-ROS calcium signaling. Using this combination, we show that the troponin C-dependent increase in myoplasmic calcium buffering during myocyte stretching largely offsets the X-ROS-dependent increase in calcium release from the sarcoplasmic reticulum. The combination of modeling and experiment are further informed by the elimination of length-dependent changes to troponin C calcium binding in the presence of blebbistatin. Here, the model suggests that it is the X-ROS signaling-dependent Ca2+ release increase that serves to maintain free myoplasmic calcium concentrations during a change in myocyte length. Together, our experimental and modeling approaches have further defined the relative contributions of X-ROS signaling and the length-dependent calcium buffering by troponin in shaping the myoplasmic calcium transient.
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Affiliation(s)
- Sarita Limbu
- School of Systems Biology and The Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA;
| | - Benjamin L. Prosser
- Department of Physiology, Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA;
| | - William J. Lederer
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 20201, USA;
| | - Christopher W. Ward
- Center for Biomedical Engineering and Technology and Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 20201, USA;
| | - Mohsin S. Jafri
- School of Systems Biology and The Krasnow Institute for Advanced Study, George Mason University, Fairfax, VA 22030, USA;
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 20201, USA;
- Correspondence: ; Tel.: +1-703-993-8420
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23
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Modulations of Cardiac Functions and Pathogenesis by Reactive Oxygen Species and Natural Antioxidants. Antioxidants (Basel) 2021; 10:antiox10050760. [PMID: 34064823 PMCID: PMC8150787 DOI: 10.3390/antiox10050760] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 05/03/2021] [Accepted: 05/08/2021] [Indexed: 01/11/2023] Open
Abstract
Homeostasis in the level of reactive oxygen species (ROS) in cardiac myocytes plays a critical role in regulating their physiological functions. Disturbance of balance between generation and removal of ROS is a major cause of cardiac myocyte remodeling, dysfunction, and failure. Cardiac myocytes possess several ROS-producing pathways, such as mitochondrial electron transport chain, NADPH oxidases, and nitric oxide synthases, and have endogenous antioxidation mechanisms. Cardiac Ca2+-signaling toolkit proteins, as well as mitochondrial functions, are largely modulated by ROS under physiological and pathological conditions, thereby producing alterations in contraction, membrane conductivity, cell metabolism and cell growth and death. Mechanical stresses under hypertension, post-myocardial infarction, heart failure, and valve diseases are the main causes for stress-induced cardiac remodeling and functional failure, which are associated with ROS-induced pathogenesis. Experimental evidence demonstrates that many cardioprotective natural antioxidants, enriched in foods or herbs, exert beneficial effects on cardiac functions (Ca2+ signal, contractility and rhythm), myocytes remodeling, inflammation and death in pathological hearts. The review may provide knowledge and insight into the modulation of cardiac pathogenesis by ROS and natural antioxidants.
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Asulin M, Michael I, Shapira A, Dvir T. One-Step 3D Printing of Heart Patches with Built-In Electronics for Performance Regulation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2004205. [PMID: 33977062 PMCID: PMC8097332 DOI: 10.1002/advs.202004205] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 12/23/2020] [Indexed: 06/12/2023]
Abstract
Three dimensional (3D) printing of heart patches usually provides the ability to precisely control cell location in 3D space. Here, one-step 3D printing of cardiac patches with built-in soft and stretchable electronics is reported. The tissue is simultaneously printed using three distinct bioinks for the cells, for the conducting parts of the electronics and for the dielectric components. It is shown that the hybrid system can withstand continuous physical deformations as those taking place in the contracting myocardium. The electronic patch is flexible, stretchable, and soft, and the electrodes within the printed patch are able to monitor the function of the engineered tissue by providing extracellular potentials. Furthermore, the system allowed controlling tissue function by providing electrical stimulation for pacing. It is envisioned that such transplantable patches may regain heart contractility and allow the physician to monitor the implant function as well as to efficiently intervene from afar when needed.
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Affiliation(s)
- Masha Asulin
- The Shmunis School of Biomedicine and Cancer ResearchFaculty of Life SciencesTel Aviv UniversityTel Aviv6997801Israel
- Department of Materials Science and EngineeringFaculty of EngineeringTel Aviv UniversityTel Aviv6997801Israel
| | - Idan Michael
- The Shmunis School of Biomedicine and Cancer ResearchFaculty of Life SciencesTel Aviv UniversityTel Aviv6997801Israel
| | - Assaf Shapira
- The Shmunis School of Biomedicine and Cancer ResearchFaculty of Life SciencesTel Aviv UniversityTel Aviv6997801Israel
| | - Tal Dvir
- The Shmunis School of Biomedicine and Cancer ResearchFaculty of Life SciencesTel Aviv UniversityTel Aviv6997801Israel
- Department of Materials Science and EngineeringFaculty of EngineeringTel Aviv UniversityTel Aviv6997801Israel
- The Center for Nanoscience and NanotechnologyTel Aviv UniversityTel Aviv6997801Israel
- Sagol Center for Regenerative BiotechnologyTel Aviv UniversityTel Aviv6997801Israel
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25
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Solís C, Solaro RJ. Novel insights into sarcomere regulatory systems control of cardiac thin filament activation. J Gen Physiol 2021; 153:211903. [PMID: 33740037 PMCID: PMC7988513 DOI: 10.1085/jgp.202012777] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 02/23/2021] [Indexed: 12/11/2022] Open
Abstract
Our review focuses on sarcomere regulatory mechanisms with a discussion of cardiac-specific modifications to the three-state model of thin filament activation from a blocked to closed to open state. We discuss modulation of these thin filament transitions by Ca2+, by crossbridge interactions, and by thick filament–associated proteins, cardiac myosin–binding protein C (cMyBP-C), cardiac regulatory light chain (cRLC), and titin. Emerging evidence supports the idea that the cooperative activation of the thin filaments despite a single Ca2+ triggering regulatory site on troponin C (cTnC) cannot be considered in isolation of other functional domains of the sarcomere. We discuss long- and short-range interactions among these domains with the regulatory units of thin filaments, including proteins at the barbed end at the Z-disc and the pointed end near the M-band. Important to these discussions is the ever-increasing understanding of the role of cMyBP-C, cRLC, and titin filaments. Detailed knowledge of these control processes is critical to the understanding of mechanisms sustaining physiological cardiac state with varying hemodynamic load, to better defining genetic and acquired cardiac disorders, and to developing targets for therapies at the level of the sarcomeres.
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Affiliation(s)
- Christopher Solís
- University of Illinois at Chicago, College of Medicine, Department of Physiology and Biophysics and Center for Cardiovascular Research, Chicago, IL
| | - R John Solaro
- University of Illinois at Chicago, College of Medicine, Department of Physiology and Biophysics and Center for Cardiovascular Research, Chicago, IL
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26
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Zavala MR, Díaz RG, Villa-Abrille MC, Pérez NG. Thioredoxin 1 (TRX1) Overexpression Cancels the Slow Force Response (SFR) Development. Front Cardiovasc Med 2021; 8:622583. [PMID: 33718450 PMCID: PMC7952880 DOI: 10.3389/fcvm.2021.622583] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/18/2021] [Indexed: 11/28/2022] Open
Abstract
The stretch of cardiac muscle increases developed force in two phases. The first phase occurs immediately after stretch and is the expression of the Frank–Starling mechanism, while the second one or slow force response (SFR) occurs gradually and is due to an increase in the calcium transient amplitude. An important step in the chain of events leading to the SFR generation is the increased production of reactive oxygen species (ROS) leading to redox sensitive ERK1/2, p90RSK, and NHE1 phosphorylation/activation. Conversely, suppression of ROS production blunts the SFR. The purpose of this study was to explore whether overexpression of the ubiquitously expressed antioxidant molecule thioredoxin-1 (TRX1) affects the SFR development and NHE1 phosphorylation. We did not detect any change in basal phopho-ERK1/2, phopho-p90RSK, and NHE1 expression in mice with TRX1 overexpression compared to wild type (WT). Isolated papillary muscles from WT or TRX1-overexpressing mice were stretched from 92 to 98% of its maximal length. A prominent SFR was observed in WT mice that was completely canceled in TRX1 animals. Interestingly, myocardial stretch induced a significant increase in NHE1 phosphorylation in WT mice that was not detected in TRX1-overexpressing mice. These novel results suggest that magnification of cardiac antioxidant defense power by overexpression of TRX1 precludes NHE1 phosphorylation/activation after stretch, consequently blunting the SFR development.
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Affiliation(s)
- Maite R Zavala
- Fellow From Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Romina G Díaz
- Established Investigators of CONICET, Buenos Aires, Argentina
| | - María C Villa-Abrille
- Established Investigators of CONICET, Buenos Aires, Argentina.,Full Professors of Physiology, Facultad de Ciencias Médicas de La Plata, Universidad Nacional de La Plata, Buenos Aires, Argentina
| | - Néstor G Pérez
- Established Investigators of CONICET, Buenos Aires, Argentina.,Full Professors of Physiology, Facultad de Ciencias Médicas de La Plata, Universidad Nacional de La Plata, Buenos Aires, Argentina
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27
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Jiang F, Yin K, Wu K, Zhang M, Wang S, Cheng H, Zhou Z, Xiao B. The mechanosensitive Piezo1 channel mediates heart mechano-chemo transduction. Nat Commun 2021; 12:869. [PMID: 33558521 PMCID: PMC7870949 DOI: 10.1038/s41467-021-21178-4] [Citation(s) in RCA: 97] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 01/19/2021] [Indexed: 01/20/2023] Open
Abstract
The beating heart possesses the intrinsic ability to adapt cardiac output to changes in mechanical load. The century-old Frank-Starling law and Anrep effect have documented that stretching the heart during diastolic filling increases its contractile force. However, the molecular mechanotransduction mechanism and its impact on cardiac health and disease remain elusive. Here we show that the mechanically activated Piezo1 channel converts mechanical stretch of cardiomyocytes into Ca2+ and reactive oxygen species (ROS) signaling, which critically determines the mechanical activity of the heart. Either cardiac-specific knockout or overexpression of Piezo1 in mice results in defective Ca2+ and ROS signaling and the development of cardiomyopathy, demonstrating a homeostatic role of Piezo1. Piezo1 is pathologically upregulated in both mouse and human diseased hearts via an autonomic response of cardiomyocytes. Thus, Piezo1 serves as a key cardiac mechanotransducer for initiating mechano-chemo transduction and consequently maintaining normal heart function, and might represent a novel therapeutic target for treating human heart diseases.
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Affiliation(s)
- Fan Jiang
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, IDG/McGovern Institute for Brain Research, School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China
| | - Kunlun Yin
- State Key Laboratory of Cardiovascular Disease, Beijing Key Laboratory for Molecular Diagnostics of Cardiovascular Diseases, Center of Laboratory Medicine, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Kun Wu
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, IDG/McGovern Institute for Brain Research, School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China
- Medical Research Center, Beijing Key Laboratory of Cardiopulmonary Cerebral Resuscitation, Department of Emergency, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Mingmin Zhang
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, IDG/McGovern Institute for Brain Research, School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China
| | - Shiqiang Wang
- State Key Laboratory of Membrane Biology, College of Life Sciences and Institute of Molecular Medicine, Peking University, Beijing, China
| | - Heping Cheng
- State Key Laboratory of Membrane Biology, Institute of Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Zhou Zhou
- State Key Laboratory of Cardiovascular Disease, Beijing Key Laboratory for Molecular Diagnostics of Cardiovascular Diseases, Center of Laboratory Medicine, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Bailong Xiao
- State Key Laboratory of Membrane Biology, Tsinghua-Peking Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, IDG/McGovern Institute for Brain Research, School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China.
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28
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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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29
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Lyon A, Dupuis LJ, Arts T, Crijns HJGM, Prinzen FW, Delhaas T, Heijman J, Lumens J. Differentiating the effects of β-adrenergic stimulation and stretch on calcium and force dynamics using a novel electromechanical cardiomyocyte model. Am J Physiol Heart Circ Physiol 2020; 319:H519-H530. [PMID: 32734816 DOI: 10.1152/ajpheart.00275.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Cardiac electrophysiology and mechanics are strongly interconnected. Calcium is crucial in this complex interplay through its role in cellular electrophysiology and sarcomere contraction. We aim to differentiate the effects of acute β-adrenergic stimulation (β-ARS) and cardiomyocyte stretch (increased sarcomere length) on calcium-transient dynamics and force generation, using a novel computational model of cardiac electromechanics. We implemented a bidirectional coupling between the O'Hara-Rudy model of human ventricular electrophysiology and the MechChem model of sarcomere mechanics through the buffering of calcium by troponin. The coupled model was validated using experimental data from large mammals or human samples. Calcium transient and force were simulated for various degrees of β-ARS and initial sarcomere lengths. The model reproduced force-frequency, quick-release, and isotonic contraction experiments, validating the bidirectional electromechanical interactions. An increase in β-ARS increased the amplitudes of force (augmented inotropy) and calcium transient, and shortened both force and calcium-transient duration (lusitropy). An increase in sarcomere length increased force amplitude even more, but decreased calcium-transient amplitude and increased both force and calcium-transient duration. Finally, a gradient in relaxation along the thin filament may explain the nonmonotonic decay in cytosolic calcium observed with high tension. Using a novel coupled human electromechanical model, we identified differential effects of β-ARS and stretch on calcium and force. Stretch mostly contributed to increased force amplitude and β-ARS to the reduction of calcium and force duration. We showed that their combination, rather than individual contributions, is key to ensure force generation, rapid relaxation, and low diastolic calcium levels.NEW & NOTEWORTHY This work identifies the contribution of electrical and mechanical alterations to regulation of calcium and force under exercise-like conditions using a novel human electromechanical model integrating ventricular electrophysiology and sarcomere mechanics. By better understanding their individual and combined effects, this can uncover arrhythmogenic mechanisms in exercise-like situations. This publicly available model is a crucial step toward understanding the complex interplay between cardiac electrophysiology and mechanics to improve arrhythmia risk prediction and treatment.
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Affiliation(s)
- Aurore Lyon
- Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Lauren J Dupuis
- Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands.,Department of Bioinformatics-BiGCaT, School of Nutrition and Translational Research in Metabolism, Maastricht University, Maastricht, The Netherlands
| | - Theo Arts
- Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Harry J G M Crijns
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Frits W Prinzen
- Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Tammo Delhaas
- Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
| | - Jordi Heijman
- Department of Cardiology, Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Joost Lumens
- Department of Biomedical Engineering, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, The Netherlands
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30
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Guidry ME, Nickerson DP, Crampin EJ, Nash MP, Loiselle DS, Tran K. Insights From Computational Modeling Into the Contribution of Mechano-Calcium Feedback on the Cardiac End-Systolic Force-Length Relationship. Front Physiol 2020; 11:587. [PMID: 32547426 PMCID: PMC7273927 DOI: 10.3389/fphys.2020.00587] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 05/11/2020] [Indexed: 11/23/2022] Open
Abstract
In experimental studies on cardiac tissue, the end-systolic force-length relation (ESFLR) has been shown to depend on the mode of contraction: isometric or isotonic. The isometric ESFLR is derived from isometric contractions spanning a range of muscle lengths while the isotonic ESFLR is derived from shortening contractions across a range of afterloads. The ESFLR of isotonic contractions consistently lies below its isometric counterpart. Despite the passing of over a hundred years since the first insight by Otto Frank, the mechanism(s) underlying this protocol-dependent difference in the ESFLR remain incompletely explained. Here, we investigate the role of mechano-calcium feedback in accounting for the difference between these two ESFLRs. Previous studies have compared the dynamics of isotonic contractions to those of a single isometric contraction at a length that produces maximum force, without considering isometric contractions at shorter muscle lengths. We used a mathematical model of cardiac excitation-contraction to simulate isometric and force-length work-loop contractions (the latter being the 1D equivalent of the whole-heart pressure-volume loop), and compared Ca2+ transients produced under equivalent force conditions. We found that the duration of the simulated Ca2+ transient increases with decreasing sarcomere length for isometric contractions, and increases with decreasing afterload for work-loop contractions. At any given force, the Ca2+ transient for an isometric contraction is wider than that during a work-loop contraction. By driving simulated work-loops with wider Ca2+ transients generated from isometric contractions, we show that the duration of muscle shortening was prolonged, thereby shifting the work-loop ESFLR toward the isometric ESFLR. These observations are explained by an increase in the rate of binding of Ca2+ to troponin-C with increasing force. However, the leftward shift of the work-loop ESFLR does not superimpose on the isometric ESFLR, leading us to conclude that while mechano-calcium feedback does indeed contribute to the difference between the two ESFLRs, it does not completely account for it.
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Affiliation(s)
- Megan E Guidry
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - David P Nickerson
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Edmund J Crampin
- Systems Biology Laboratory, School of Mathematics and Statistics, The University of Melbourne, Melbourne, VIC, Australia.,ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, School of Chemical and Biomedical Engineering, The University of Melbourne, Melbourne, VIC, Australia
| | - Martyn P Nash
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.,Department of Engineering Science, The University of Auckland, Auckland, New Zealand
| | - Denis S Loiselle
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand.,Department of Physiology, The University of Auckland, Auckland, New Zealand
| | - Kenneth Tran
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
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31
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Quinn TA, Kohl P. Cardiac Mechano-Electric Coupling: Acute Effects of Mechanical Stimulation on Heart Rate and Rhythm. Physiol Rev 2020; 101:37-92. [PMID: 32380895 DOI: 10.1152/physrev.00036.2019] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The heart is vital for biological function in almost all chordates, including humans. It beats continually throughout our life, supplying the body with oxygen and nutrients while removing waste products. If it stops, so does life. The heartbeat involves precise coordination of the activity of billions of individual cells, as well as their swift and well-coordinated adaption to changes in physiological demand. Much of the vital control of cardiac function occurs at the level of individual cardiac muscle cells, including acute beat-by-beat feedback from the local mechanical environment to electrical activity (as opposed to longer term changes in gene expression and functional or structural remodeling). This process is known as mechano-electric coupling (MEC). In the current review, we present evidence for, and implications of, MEC in health and disease in human; summarize our understanding of MEC effects gained from whole animal, organ, tissue, and cell studies; identify potential molecular mediators of MEC responses; and demonstrate the power of computational modeling in developing a more comprehensive understanding of ‟what makes the heart tick.ˮ.
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Affiliation(s)
- T Alexander Quinn
- Department of Physiology and Biophysics and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical Faculty of the University of Freiburg, Freiburg, Germany; and CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
| | - Peter Kohl
- Department of Physiology and Biophysics and School of Biomedical Engineering, Dalhousie University, Halifax, Nova Scotia, Canada; Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Medical Faculty of the University of Freiburg, Freiburg, Germany; and CIBSS-Centre for Integrative Biological Signalling Studies, University of Freiburg, Freiburg, Germany
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32
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Izu LT, Kohl P, Boyden PA, Miura M, Banyasz T, Chiamvimonvat N, Trayanova N, Bers DM, Chen-Izu Y. Mechano-electric and mechano-chemo-transduction in cardiomyocytes. J Physiol 2020; 598:1285-1305. [PMID: 31789427 PMCID: PMC7127983 DOI: 10.1113/jp276494] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 11/21/2019] [Indexed: 12/11/2022] Open
Abstract
Cardiac excitation-contraction (E-C) coupling is influenced by (at least) three dynamic systems that couple and feedback to one another (see Abstract Figure). Here we review the mechanical effects on cardiomyocytes that include mechano-electro-transduction (commonly referred to as mechano-electric coupling, MEC) and mechano-chemo-transduction (MCT) mechanisms at cell and molecular levels which couple to Ca2+ -electro and E-C coupling reviewed elsewhere. These feedback loops from muscle contraction and mechano-transduction to the Ca2+ homeodynamics and to the electrical excitation are essential for understanding the E-C coupling dynamic system and arrhythmogenesis in mechanically loaded hearts. This white paper comprises two parts, each reflecting key aspects from the 2018 UC Davis symposium: MEC (how mechanical load influences electrical dynamics) and MCT (how mechanical load alters cell signalling and Ca2+ dynamics). Of course, such separation is artificial since Ca2+ dynamics profoundly affect ion channels and electrogenic transporters and vice versa. In time, these dynamic systems and their interactions must become fully integrated, and that should be a goal for a comprehensive understanding of how mechanical load influences cell signalling, Ca2+ homeodynamics and electrical dynamics. In this white paper we emphasize current understanding, consensus, controversies and the pressing issues for future investigations. Space constraints make it impossible to cover all relevant articles in the field, so we will focus on the topics discussed at the symposium.
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Affiliation(s)
- Leighton T. Izu
- Department of Pharmacology, University of California, Davis, CA 95616, USA
| | - Peter Kohl
- Institute for Experimental Cardiovascular Medicine, University Heart Centre, and Faculty of Medicine, University of Freiburg, D-79110, Germany
| | | | - Masahito Miura
- Department of Clinical Physiology, Health Science, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan
| | - Tamas Banyasz
- Department of Physiology, University of Debrecen, Debrecen, Hungary
| | - Nipavan Chiamvimonvat
- Department of Internal Medicine, Cardiovascular Medicine, University of California, Davis, USA
| | - Natalia Trayanova
- Department of Department of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Donald M. Bers
- Department of Pharmacology, University of California, Davis, CA 95616, USA
| | - Ye Chen-Izu
- Department of Pharmacology, University of California, Davis, CA 95616, USA
- Department of Internal Medicine, Cardiovascular Medicine, University of California, Davis, USA
- Department of Biomedical Engineering, University of California, Davis, CA 95616, USA
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33
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Cardiomyocyte calcium handling in health and disease: Insights from in vitro and in silico studies. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 157:54-75. [PMID: 32188566 DOI: 10.1016/j.pbiomolbio.2020.02.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 12/31/2019] [Accepted: 02/29/2020] [Indexed: 02/07/2023]
Abstract
Calcium (Ca2+) plays a central role in cardiomyocyte excitation-contraction coupling. To ensure an optimal electrical impulse propagation and cardiac contraction, Ca2+ levels are regulated by a variety of Ca2+-handling proteins. In turn, Ca2+ modulates numerous electrophysiological processes. Accordingly, Ca2+-handling abnormalities can promote cardiac arrhythmias via various mechanisms, including the promotion of afterdepolarizations, ion-channel modulation and structural remodeling. In the last 30 years, significant improvements have been made in the computational modeling of cardiomyocyte Ca2+ handling under physiological and pathological conditions. However, numerous questions involving the Ca2+-dependent regulation of different macromolecular complexes, cross-talk between Ca2+-dependent regulatory pathways operating over a wide range of time scales, and bidirectional interactions between electrophysiology and mechanics remain to be addressed by in vitro and in silico studies. A better understanding of disease-specific Ca2+-dependent proarrhythmic mechanisms may facilitate the development of improved therapeutic strategies. In this review, we describe the fundamental mechanisms of cardiomyocyte Ca2+ handling in health and disease, and provide an overview of currently available computational models for cardiomyocyte Ca2+ handling. Finally, we discuss important uncertainties and open questions about cardiomyocyte Ca2+ handling and highlight how synergy between in vitro and in silico studies may help to answer several of these issues.
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34
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Seo K, Parikh VN, Ashley EA. Stretch-Induced Biased Signaling in Angiotensin II Type 1 and Apelin Receptors for the Mediation of Cardiac Contractility and Hypertrophy. Front Physiol 2020; 11:181. [PMID: 32231588 PMCID: PMC7082839 DOI: 10.3389/fphys.2020.00181] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Accepted: 02/17/2020] [Indexed: 12/18/2022] Open
Abstract
The myocardium has an intrinsic ability to sense and respond to mechanical load in order to adapt to physiological demands. Primary examples are the augmentation of myocardial contractility in response to increased ventricular filling caused by either increased venous return (Frank-Starling law) or aortic resistance to ejection (the Anrep effect). Sustained mechanical overload, however, can induce pathological hypertrophy and dysfunction, resulting in heart failure and arrhythmias. It has been proposed that angiotensin II type 1 receptor (AT1R) and apelin receptor (APJ) are primary upstream actors in this acute myocardial autoregulation as well as the chronic maladaptive signaling program. These receptors are thought to have mechanosensing capacity through activation of intracellular signaling via G proteins and/or the multifunctional transducer protein, β-arrestin. Importantly, ligand and mechanical stimuli can selectively activate different downstream signaling pathways to promote inotropic, cardioprotective or cardiotoxic signaling. Studies to understand how AT1R and APJ integrate ligand and mechanical stimuli to bias downstream signaling are an important and novel area for the discovery of new therapeutics for heart failure. In this review, we provide an up-to-date understanding of AT1R and APJ signaling pathways activated by ligand versus mechanical stimuli, and their effects on inotropy and adaptive/maladaptive hypertrophy. We also discuss the possibility of targeting these signaling pathways for the development of novel heart failure therapeutics.
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Affiliation(s)
- Kinya Seo
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, CA, United States
| | - Victoria N. Parikh
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, CA, United States
| | - Euan A. Ashley
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University, Stanford, CA, United States
- Department of Genetics, Stanford University, Stanford, CA, United States
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35
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Takeuchi A, Matsuoka S. Integration of mitochondrial energetics in heart with mathematical modelling. J Physiol 2020; 598:1443-1457. [DOI: 10.1113/jp276817] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 01/23/2020] [Indexed: 11/08/2022] Open
Affiliation(s)
- Ayako Takeuchi
- Department of Integrative and Systems PhysiologyFaculty of Medical Sciencesand Life Science Innovation CenterUniversity of Fukui Fukui 910‐1193 Japan
| | - Satoshi Matsuoka
- Department of Integrative and Systems PhysiologyFaculty of Medical Sciencesand Life Science Innovation CenterUniversity of Fukui Fukui 910‐1193 Japan
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36
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Balakina-Vikulova NA, Panfilov A, Solovyova O, Katsnelson LB. Mechano-calcium and mechano-electric feedbacks in the human cardiomyocyte analyzed in a mathematical model. J Physiol Sci 2020; 70:12. [PMID: 32070290 PMCID: PMC7028825 DOI: 10.1186/s12576-020-00741-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 02/04/2020] [Indexed: 12/11/2022]
Abstract
Experiments on animal hearts (rat, rabbit, guinea pig, etc.) have demonstrated that mechano-calcium feedback (MCF) and mechano-electric feedback (MEF) are very important for myocardial self-regulation because they adjust the cardiomyocyte contractile function to various mechanical loads and to mechanical interactions between heterogeneous myocardial segments in the ventricle walls. In in vitro experiments on these animals, MCF and MEF manifested themselves in several basic classical phenomena (e.g., load dependence, length dependence of isometric twitches, etc.), and in the respective responses of calcium transients and action potentials. However, it is extremely difficult to study simultaneously the electrical, calcium, and mechanical activities of the human heart muscle in vitro. Mathematical modeling is a useful tool for exploring these phenomena. We have developed a novel model to describe electromechanical coupling and mechano-electric feedbacks in the human cardiomyocyte. It combines the ‘ten Tusscher–Panfilov’ electrophysiological model of the human cardiomyocyte with our module of myocardium mechanical activity taken from the ‘Ekaterinburg–Oxford’ model and adjusted to human data. Using it, we simulated isometric and afterloaded twitches and effects of MCF and MEF on excitation–contraction coupling. MCF and MEF were found to affect significantly the duration of the calcium transient and action potential in the human cardiomyocyte model in response to both smaller afterloads as compared to bigger ones and various mechanical interventions applied during isometric and afterloaded twitches.
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Affiliation(s)
- Nathalie A Balakina-Vikulova
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia. .,Ural Federal University, Ekaterinburg, Russia.
| | - Alexander Panfilov
- Ural Federal University, Ekaterinburg, Russia.,Ghent University, Ghent, Belgium
| | - Olga Solovyova
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia.,Ural Federal University, Ekaterinburg, Russia
| | - Leonid B Katsnelson
- Institute of Immunology and Physiology of the Ural Branch of the Russian Academy of Sciences, Ekaterinburg, Russia.,Ural Federal University, Ekaterinburg, Russia
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37
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Kaur S, Shen X, Power A, Ward ML. Stretch modulation of cardiac contractility: importance of myocyte calcium during the slow force response. Biophys Rev 2020; 12:135-142. [PMID: 31939110 DOI: 10.1007/s12551-020-00615-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 01/07/2020] [Indexed: 12/11/2022] Open
Abstract
The mechanical response of the heart to myocardial stretch has been understood since the work of muscle physiologists more than 100 years ago, whereby an increase in ventricular chamber filling during diastole increases the subsequent force of contraction. The stretch-induced increase in contraction is biphasic. There is an abrupt increase in the force that coincides with the stretch (the rapid response), which is then followed by a slower response that develops over several minutes (the slow force response, or SFR). The SFR is associated with a progressive increase in the magnitude of the Ca2+ transient, the event that initiates myocyte cross-bridge cycling and force development. However, the mechanisms underlying the stretch-dependent increase in the Ca2+ transient are still debated. This review outlines recent literature on the SFR and summarizes the different stretch-activated Ca2+ entry pathways. The SFR might result from a combination of several different cellular mechanisms initiated in response to activation of different cellular stretch sensors.
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Affiliation(s)
- Sarbjot Kaur
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Xin Shen
- Institute for Experimental Medical Research, Oslo University Hospital and University of Oslo, Oslo, Norway.,K.G.Jebsen Center for Cardiac Research, Oslo, Norway
| | - Amelia Power
- Department of Physiology, University of Otago, Dunedin, New Zealand
| | - Marie-Louise Ward
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
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Yamada T, Ashida Y, Tatebayashi D, Himori K. Myofibrillar function differs markedly between denervated and dexamethasone-treated rat skeletal muscles: Role of mechanical load. PLoS One 2019; 14:e0223551. [PMID: 31596883 PMCID: PMC6785062 DOI: 10.1371/journal.pone.0223551] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 09/24/2019] [Indexed: 01/24/2023] Open
Abstract
Although there is good evidence to indicate a major role of intrinsic impairment of the contractile apparatus in muscle weakness seen in several pathophysiological conditions, the factors responsible for control of myofibrillar function are not fully understood. To investigate the role of mechanical load in myofibrillar function, we compared the skinned fiber force between denervated (DEN) and dexamethasone-treated (DEX) rat skeletal muscles with or without neuromuscular electrical stimulation (ES) training. DEN and DEX were induced by cutting the sciatic nerve and daily injection of dexamethasone (5 mg/kg/day) for 7 days, respectively. For ES training, plantarflexor muscles were electrically stimulated to produce four sets of five isometric contractions each day. In situ maximum torque was markedly depressed in the DEN muscles compared to the DEX muscles (-74% vs. -10%), whereas there was not much difference in the degree of atrophy in gastrocnemius muscles between DEN and DEX groups (-24% vs. -17%). Similar results were obtained in the skinned fiber preparation, with a greater reduction in maximum Ca2+-activated force in the DEN than in the DEX group (-53% vs. -16%). Moreover, there was a parallel decline in myosin heavy chain (MyHC) and actin content per muscle volume in DEN muscles, but not in DEX muscles, which was associated with upregulation of NADPH oxidase (NOX) 2, neuronal nitric oxide synthase (nNOS), and endothelial NOS expression, translocation of nNOS from the membrane to the cytosol, and augmentation of mRNA levels of muscle RING finger protein 1 (MuRF-1) and atrogin-1. Importantly, mechanical load evoked by ES protects against DEN- and DEX-induced myofibrillar dysfunction and these molecular alterations. Our findings provide novel insights regarding the difference in intrinsic contractile properties between DEN and DEX and suggest an important role of mechanical load in preserving myofibrillar function in skeletal muscle.
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Affiliation(s)
- Takashi Yamada
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
- * E-mail:
| | - Yuki Ashida
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
- Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
| | - Daisuke Tatebayashi
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
| | - Koichi Himori
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
- Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
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39
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Yeves AM, Ennis IL. Na +/H + exchanger and cardiac hypertrophy. HIPERTENSION Y RIESGO VASCULAR 2019; 37:22-32. [PMID: 31601481 DOI: 10.1016/j.hipert.2019.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 08/16/2019] [Accepted: 09/03/2019] [Indexed: 12/31/2022]
Abstract
Reactive cardiac hypertrophy (CH) is an increase in heart mass in response to hemodynamic overload. Exercise-induced CH emerges as an adaptive response with improved cardiac function, in contrast to pathological CH that represents a risk factor for cardiovascular health. The Na+/H+ exchanger (NHE-1) is a membrane transporter that not only regulates intracellular pH but also intracellular Na+ concentration. In the scenario of cardiovascular diseases, myocardial NHE-1 is activated by a variety of stimuli, such as neurohumoral factors and mechanical stress, leading to intracellular Na+ overload and activation of prohypertrophic cascades. NHE-1 hyperactivity is intimately linked to heart diseases, including ischemia-reperfusion injury, maladaptive CH and heart failure. In this review, we will present evidence to support that the NHE-1 hyperactivity constitutes a "switch on/off" for the pathological phenotype during CH development. We will also discuss some classical and novel strategies to avoid NHE-1 hyperactivity, and that are therefore worthwhile to improve cardiovascular health.
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Affiliation(s)
- A M Yeves
- Centro de Investigaciones Cardiovasculares "Horacio E. Cingolani", Facultad de Ciencias Médicas, Universidad Nacional de La Plata - CONICET, Calle 60 y 120, 1900 La Plata, Argentina
| | - I L Ennis
- Centro de Investigaciones Cardiovasculares "Horacio E. Cingolani", Facultad de Ciencias Médicas, Universidad Nacional de La Plata - CONICET, Calle 60 y 120, 1900 La Plata, Argentina.
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40
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Sequeira V, Bertero E, Maack C. Energetic drain driving hypertrophic cardiomyopathy. FEBS Lett 2019; 593:1616-1626. [PMID: 31209876 DOI: 10.1002/1873-3468.13496] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 06/07/2019] [Accepted: 06/13/2019] [Indexed: 01/09/2023]
Abstract
Hypertrophic cardiomyopathy (HCM) is the most common form of hereditary cardiomyopathy and is mainly caused by mutations of genes encoding cardiac sarcomeric proteins. HCM is characterized by hypertrophy of the left ventricle, frequently involving the septum, that is not explained solely by loading conditions. HCM has a heterogeneous clinical profile, but diastolic dysfunction and ventricular arrhythmias represent two dominant features of the disease. Preclinical evidence indicates that the enhanced Calcium (Ca2+ ) sensitivity of the myofilaments plays a key role in the pathophysiology of HCM. Notably, this is not always a direct consequence of sarcomeric mutations, but can also result from secondary mutation-driven alterations. Here, we review experimental and clinical evidence indicating that increased myofilament Ca2+ sensitivity lies upstream of numerous cellular derangements which potentially contribute to the progression of HCM toward heart failure and sudden cardiac death.
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Affiliation(s)
- Vasco Sequeira
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Germany
| | - Edoardo Bertero
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Germany
| | - Christoph Maack
- Comprehensive Heart Failure Center (CHFC), University Clinic Würzburg, Germany
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41
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Himori K, Tatebayashi D, Ashida Y, Yamada T. Eccentric training enhances the αB-crystallin binding to the myofibrils and prevents skeletal muscle weakness in adjuvant-induced arthritis rat. J Appl Physiol (1985) 2019; 127:71-80. [DOI: 10.1152/japplphysiol.00102.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Patients with rheumatoid arthritis (RA) frequently suffer from muscle weakness. We examined whether eccentric training prevents skeletal muscle weakness in adjuvant-induced arthritis (AIA) rat, a widely used animal model for RA. AIA was induced in the knees of Wistar rats by injection of complete Freund’s adjuvant. To induce eccentric contractions (ECCs), neuromuscular electrical stimulation (45 V) was applied to the plantar flexor muscles simultaneously with forced dorsiflexion of the ankle joint (0–40°) and was given every 6 s. ECC exercise was applied every other day for a total of 11 sessions and consisted of 4 sets of 5 contractions. There was a significant reduction in in vitro maximum Ca2+-activated force in skinned fibers in gastrocnemius muscle from AIA rats. These changes were associated with reduced expression levels of contractile proteins (i.e., myosin and actin), increased levels of inflammation redox stress-related biomarkers (i.e., TNF-α, malondialdehyde-protein adducts, NADPH oxidase 2, and neuronal nitric oxide synthase), and autolyzed active calpain-1 in AIA muscles. ECC training markedly enhanced the steady-state levels of αB-crystallin, a small heat shock protein, and its binding to the myofibrils and prevented the AIA-induced myofibrillar dysfunction, reduction in contractile proteins, and inflammation-oxidative stress insults. Our findings demonstrate that ECC training preserves myofibrillar function without muscle damage in AIA rats, which is at least partially attributable to the protective effect of αB-crystallin on the myofibrils against oxidative stress-mediated protein degeneration. Thus ECC training can be a safe and effective intervention, counteracting the loss of muscle strength in RA patients. NEW & NOTEWORTHY Eccentric contractions (ECCs) are regarded as an effective way to increase muscle strength. No studies, however, assess safety and effectiveness of ECC training on muscle weakness associated with rheumatoid arthritis. Here, we used adjuvant-induced arthritis (AIA) rats to demonstrate that ECC training prevents intrinsic contractile dysfunction without muscle damage in AIA rats, which may be attributed to the protective effect of αB-crystallin on the myofibrils against inflammation-oxidative stress insults.
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Affiliation(s)
- Koichi Himori
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
| | - Daisuke Tatebayashi
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
| | - Yuki Ashida
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
| | - Takashi Yamada
- Graduate School of Health Sciences, Sapporo Medical University, Sapporo, Japan
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42
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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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43
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Dowrick JM, Tran K, Loiselle DS, Nielsen PMF, Taberner AJ, Han J, Ward M. The slow force response to stretch: Controversy and contradictions. Acta Physiol (Oxf) 2019; 226:e13250. [PMID: 30614655 DOI: 10.1111/apha.13250] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/20/2018] [Accepted: 01/02/2019] [Indexed: 12/19/2022]
Abstract
When exposed to an abrupt stretch, cardiac muscle exhibits biphasic active force enhancement. The initial, instantaneous, force enhancement is well explained by the Frank-Starling mechanism. However, the cellular mechanisms associated with the second, slower phase remain contentious. This review explores hypotheses regarding this "slow force response" with the intention of clarifying some apparent contradictions in the literature. The review is partitioned into three sections. The first section considers pathways that modify the intracellular calcium handling to address the role of the sarcoplasmic reticulum in the mechanism underlying the slow force response. The second section focuses on extracellular calcium fluxes and explores the identity and contribution of the stretch-activated, non-specific, cation channels as well as signalling cascades associated with G-protein coupled receptors. The final section introduces promising candidates for the mechanosensor(s) responsible for detecting the stretch perturbation.
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Affiliation(s)
- Jarrah M. Dowrick
- Auckland Bioengineering Institute University of Auckland Auckland New Zealand
| | - Kenneth Tran
- Auckland Bioengineering Institute University of Auckland Auckland New Zealand
| | - Denis S. Loiselle
- Auckland Bioengineering Institute University of Auckland Auckland New Zealand
- Department of Physiology University of Auckland Auckland New Zealand
| | - Poul M. F. Nielsen
- Auckland Bioengineering Institute University of Auckland Auckland New Zealand
- Department of Engineering Science University of Auckland Auckland New Zealand
| | - Andrew J. Taberner
- Auckland Bioengineering Institute University of Auckland Auckland New Zealand
- Department of Engineering Science University of Auckland Auckland New Zealand
| | - June‐Chiew Han
- Auckland Bioengineering Institute University of Auckland Auckland New Zealand
| | - Marie‐Louise Ward
- Department of Physiology University of Auckland Auckland New Zealand
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44
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Feiner R, Wertheim L, Gazit D, Kalish O, Mishal G, Shapira A, Dvir T. A Stretchable and Flexible Cardiac Tissue-Electronics Hybrid Enabling Multiple Drug Release, Sensing, and Stimulation. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1805526. [PMID: 30838769 PMCID: PMC7100044 DOI: 10.1002/smll.201805526] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 02/17/2019] [Indexed: 04/14/2023]
Abstract
Replacement of the damaged scar tissue created by a myocardial infarction is the goal of cardiac tissue engineering. However, once the implanted tissue is in place, monitoring its function is difficult and involves indirect methods, while intervention necessarily requires an invasive procedure and available medical attention. To overcome this, methods of integrating electronic components into engineered tissues have been recently presented. These allow for remote monitoring of tissue function as well as intervention through stimulation and controlled drug release. Here, an improved hybrid microelectronic tissue construct capable of withstanding the dynamic environment of the beating heart without compromising electronic or mechanical functionality is reported. While the reported system is enabled to sense the function of the engineered tissue and provide stimulation for pacing, an electroactive polymer on the electronics enables it to release multiple drugs in parallel. It is envisioned that the integration of microelectronic devices into engineered tissues will provide a better way to monitor patient health from afar, as well as provide facile, more exact methods to control the healing process.
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Affiliation(s)
- Ron Feiner
- School for Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Lior Wertheim
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv 69978, Israel
- Department of Materials Science and Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Danielle Gazit
- School for Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Or Kalish
- School for Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Gal Mishal
- Department of Materials Science and Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Assaf Shapira
- School for Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel
| | - Tal Dvir
- School for Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel
- The Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv 69978, Israel
- Department of Materials Science and Engineering, Tel Aviv University, Tel Aviv 69978, Israel
- Sagol Center for Regenerative Biotechnology, Tel Aviv University, Tel Aviv 69978, Israel
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45
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van der Velden J, Stienen GJM. Cardiac Disorders and Pathophysiology of Sarcomeric Proteins. Physiol Rev 2019; 99:381-426. [PMID: 30379622 DOI: 10.1152/physrev.00040.2017] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The sarcomeric proteins represent the structural building blocks of heart muscle, which are essential for contraction and relaxation. During recent years, it has become evident that posttranslational modifications of sarcomeric proteins, in particular phosphorylation, tune cardiac pump function at rest and during exercise. This delicate, orchestrated interaction is also influenced by mutations, predominantly in sarcomeric proteins, which cause hypertrophic or dilated cardiomyopathy. In this review, we follow a bottom-up approach starting from a description of the basic components of cardiac muscle at the molecular level up to the various forms of cardiac disorders at the organ level. An overview is given of sarcomere changes in acquired and inherited forms of cardiac disease and the underlying disease mechanisms with particular reference to human tissue. A distinction will be made between the primary defect and maladaptive/adaptive secondary changes. Techniques used to unravel functional consequences of disease-induced protein changes are described, and an overview of current and future treatments targeted at sarcomeric proteins is given. The current evidence presented suggests that sarcomeres not only form the basis of cardiac muscle function but also represent a therapeutic target to combat cardiac disease.
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Affiliation(s)
- Jolanda van der Velden
- Amsterdam UMC, Vrije Universiteit Amsterdam, Physiology, Amsterdam Cardiovascular Sciences, Amsterdam , The Netherlands ; and Department of Physiology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Ger J M Stienen
- Amsterdam UMC, Vrije Universiteit Amsterdam, Physiology, Amsterdam Cardiovascular Sciences, Amsterdam , The Netherlands ; and Department of Physiology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
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46
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Kim JC, Son MJ, Woo SH. Regulation of cardiac calcium by mechanotransduction: Role of mitochondria. Arch Biochem Biophys 2018; 659:33-41. [DOI: 10.1016/j.abb.2018.09.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 09/28/2018] [Indexed: 12/27/2022]
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47
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Janssen PML. Myocardial relaxation in human heart failure: Why sarcomere kinetics should be center-stage. Arch Biochem Biophys 2018; 661:145-148. [PMID: 30447209 DOI: 10.1016/j.abb.2018.11.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 10/12/2018] [Accepted: 11/13/2018] [Indexed: 12/19/2022]
Abstract
Myocardial relaxation is critical for the heart to allow for adequate filling of the ventricles prior to the next contraction. In human heart failure, impairment of myocardial relaxation is a major problem, and impacts most patients suffering from end-stage failure. Furthering our understanding of myocardial relaxation is critical in developing future treatment strategies. This review highlights processes involved in myocardial relaxation, as well as governing processes that modulate myocardial relaxation, with a focus on impairment of myocardium-level relaxation in human end-stage heart failure.
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Affiliation(s)
- Paul M L Janssen
- Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, USA; Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, USA; Department of Internal Medicine, The Ohio State University Wexner Medical Center, USA.
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48
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Johnson DM, Antoons G. Arrhythmogenic Mechanisms in Heart Failure: Linking β-Adrenergic Stimulation, Stretch, and Calcium. Front Physiol 2018; 9:1453. [PMID: 30374311 PMCID: PMC6196916 DOI: 10.3389/fphys.2018.01453] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 09/25/2018] [Indexed: 12/22/2022] Open
Abstract
Heart failure (HF) is associated with elevated sympathetic tone and mechanical load. Both systems activate signaling transduction pathways that increase cardiac output, but eventually become part of the disease process itself leading to further worsening of cardiac function. These alterations can adversely contribute to electrical instability, at least in part due to the modulation of Ca2+ handling at the level of the single cardiac myocyte. The major aim of this review is to provide a definitive overview of the links and cross talk between β-adrenergic stimulation, mechanical load, and arrhythmogenesis in the setting of HF. We will initially review the role of Ca2+ in the induction of both early and delayed afterdepolarizations, the role that β-adrenergic stimulation plays in the initiation of these and how the propensity for these may be altered in HF. We will then go onto reviewing the current data with regards to the link between mechanical load and afterdepolarizations, the associated mechano-sensitivity of the ryanodine receptor and other stretch activated channels that may be associated with HF-associated arrhythmias. Furthermore, we will discuss how alterations in local Ca2+ microdomains during the remodeling process associated the HF may contribute to the increased disposition for β-adrenergic or stretch induced arrhythmogenic triggers. Finally, the potential mechanisms linking β-adrenergic stimulation and mechanical stretch will be clarified, with the aim of finding common modalities of arrhythmogenesis that could be targeted by novel therapeutic agents in the setting of HF.
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Affiliation(s)
- Daniel M Johnson
- Department of Cardiothoracic Surgery, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
| | - Gudrun Antoons
- Department of Physiology, Cardiovascular Research Institute Maastricht, Maastricht University, Maastricht, Netherlands
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49
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High tension in sarcomeres hinders myocardial relaxation: A computational study. PLoS One 2018; 13:e0204642. [PMID: 30286135 PMCID: PMC6171862 DOI: 10.1371/journal.pone.0204642] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 09/12/2018] [Indexed: 11/19/2022] Open
Abstract
Experiments have shown that the relaxation phase of cardiac sarcomeres during an isometric twitch is prolonged in muscles that reached a higher peak tension. However, the mechanism is not completely understood. We hypothesize that the binding of calcium to troponin is enhanced by the tension in the thin filament, thus contributing to the prolongation of contraction upon higher peak tension generation. To test this hypothesis, we developed a computational model of sarcomere mechanics that incorporates tension-dependence of calcium binding. The model was used to simulate isometric twitch experiments with time dependency in the form of a two-state cross-bridge cycle model and a transient intracellular calcium concentration. In the simulations, peak isometric twitch tension appeared to increase linearly by 51.1 KPa with sarcomere length from 1.9 μm to 2.2 μm. Experiments showed an increase of 47.3 KPa over the same range of sarcomere lengths. The duration of the twitch also increased with both sarcomere length and peak intracellular calcium concentration, likely to be induced by the inherently coupled increase of the peak tension in the thin filament. In the model simulations, the time to 50% relaxation (tR50) increased over the range of sarcomere lengths from 1.9 μm to 2.2 μm by 0.11s, comparable to the increased duration of 0.12s shown in experiments. Model simulated tR50 increased by 0.12s over the range of peak intracellular calcium concentrations from 0.87 μM to 1.45 μM. Our simulation results suggest that the prolongation of contraction at higher tension is a result of the tighter binding of Ca2+ to troponin in areas under higher tension, thus delaying the deactivation of the troponin.
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50
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Denham NC, Pearman CM, Caldwell JL, Madders GWP, Eisner DA, Trafford AW, Dibb KM. Calcium in the Pathophysiology of Atrial Fibrillation and Heart Failure. Front Physiol 2018; 9:1380. [PMID: 30337881 PMCID: PMC6180171 DOI: 10.3389/fphys.2018.01380] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 09/11/2018] [Indexed: 12/20/2022] Open
Abstract
Atrial fibrillation (AF) is commonly associated with heart failure. A bidirectional relationship exists between the two-AF exacerbates heart failure causing a significant increase in heart failure symptoms, admissions to hospital and cardiovascular death, while pathological remodeling of the atria as a result of heart failure increases the risk of AF. A comprehensive understanding of the pathophysiology of AF is essential if we are to break this vicious circle. In this review, the latest evidence will be presented showing a fundamental role for calcium in both the induction and maintenance of AF. After outlining atrial electrophysiology and calcium handling, the role of calcium-dependent afterdepolarizations and atrial repolarization alternans in triggering AF will be considered. The atrial response to rapid stimulation will be discussed, including the short-term protection from calcium overload in the form of calcium signaling silencing and the eventual progression to diastolic calcium leak causing afterdepolarizations and the development of an electrical substrate that perpetuates AF. The role of calcium in the bidirectional relationship between heart failure and AF will then be covered. The effects of heart failure on atrial calcium handling that promote AF will be reviewed, including effects on both atrial myocytes and the pulmonary veins, before the aspects of AF which exacerbate heart failure are discussed. Finally, the limitations of human and animal studies will be explored allowing contextualization of what are sometimes discordant results.
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Affiliation(s)
- Nathan C. Denham
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
| | | | | | | | | | | | - Katharine M. Dibb
- Unit of Cardiac Physiology, Division of Cardiovascular Sciences, Manchester Academic Health Science Centre, University of Manchester, Manchester, United Kingdom
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