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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; 123:2996-3009. [PMID: 38807364 DOI: 10.1016/j.bpj.2024.05.025] [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: 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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Arts T, Lyon A, Delhaas T, Kuster DWD, van der Velden J, Lumens J. Translating myosin-binding protein C and titin abnormalities to whole-heart function using a novel calcium-contraction coupling model. J Mol Cell Cardiol 2024; 190:13-23. [PMID: 38462126 DOI: 10.1016/j.yjmcc.2024.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 01/15/2024] [Accepted: 03/01/2024] [Indexed: 03/12/2024]
Abstract
Mutations in cardiac myosin-binding protein C (cMyBP-C) or titin may respectively lead to hypertrophic (HCM) or dilated (DCM) cardiomyopathies. The mechanisms leading to these phenotypes remain unclear because of the challenge of translating cellular abnormalities to whole-heart and system function. We developed and validated a novel computer model of calcium-contraction coupling incorporating the role of cMyBP-C and titin based on the key assumptions: 1) tension in the thick filament promotes cross-bridge attachment mechanochemically, 2) with increasing titin tension, more myosin heads are unlocked for attachment, and 3) cMyBP-C suppresses cross-bridge attachment. Simulated stationary calcium-tension curves, isotonic and isometric contractions, and quick release agreed with experimental data. The model predicted that a loss of cMyBP-C function decreases the steepness of the calcium-tension curve, and that more compliant titin decreases the level of passive and active tension and its dependency on sarcomere length. Integrating this cellular model in the CircAdapt model of the human heart and circulation showed that a loss of cMyBP-C function resulted in HCM-like hemodynamics with higher left ventricular end-diastolic pressures and smaller volumes. More compliant titin led to higher diastolic pressures and ventricular dilation, suggesting DCM-like hemodynamics. The novel model of calcium-contraction coupling incorporates the role of cMyBP-C and titin. Its coupling to whole-heart mechanics translates changes in cellular calcium-contraction coupling to changes in cardiac pump and circulatory function and identifies potential mechanisms by which cMyBP-C and titin abnormalities may develop into HCM and DCM phenotypes. This modeling platform may help identify distinct mechanisms underlying clinical phenotypes in cardiac diseases.
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Affiliation(s)
- Theo Arts
- Department of Biomedical Engineering, Cardiovascular Research Center Maastricht (CARIM), Maastricht University, 6200MD Maastricht, the Netherlands.
| | - Aurore Lyon
- Department of Biomedical Engineering, Cardiovascular Research Center Maastricht (CARIM), Maastricht University, 6200MD Maastricht, the Netherlands
| | - Tammo Delhaas
- Department of Biomedical Engineering, Cardiovascular Research Center Maastricht (CARIM), Maastricht University, 6200MD Maastricht, the Netherlands
| | - Diederik W D Kuster
- Department of Physiology, Amsterdam University Medical Center, 1081HZ Amsterdam, the Netherlands
| | - Jolanda van der Velden
- Department of Physiology, Amsterdam University Medical Center, 1081HZ Amsterdam, the Netherlands
| | - Joost Lumens
- Department of Biomedical Engineering, Cardiovascular Research Center Maastricht (CARIM), Maastricht University, 6200MD Maastricht, the Netherlands
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Dhawale N, Labonte D, Holt NC. The effect of muscle ultrastructure on the force, displacement and work capacity of skeletal muscle. J R Soc Interface 2024; 21:20230658. [PMID: 38774960 DOI: 10.1098/rsif.2023.0658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 03/28/2024] [Indexed: 07/31/2024] Open
Abstract
Skeletal muscle powers animal movement through interactions between the contractile proteins, actin and myosin. Structural variation contributes greatly to the variation in mechanical performance observed across muscles. In vertebrates, gross structural variation occurs in the form of changes in the muscle cross-sectional area : fibre length ratio. This results in a trade-off between force and displacement capacity, leaving work capacity unaltered. Consequently, the maximum work per unit volume-the work density-is considered constant. Invertebrate muscle also varies in muscle ultrastructure, i.e. actin and myosin filament lengths. Increasing actin and myosin filament lengths increases force capacity, but the effect on muscle fibre displacement, and thus work, capacity is unclear. We use a sliding-filament muscle model to predict the effect of actin and myosin filament lengths on these mechanical parameters for both idealized sarcomeres with fixed actin : myosin length ratios, and for real sarcomeres with known filament lengths. Increasing actin and myosin filament lengths increases stress without reducing strain capacity. A muscle with longer actin and myosin filaments can generate larger force over the same displacement and has a higher work density, so seemingly bypassing an established trade-off. However, real sarcomeres deviate from the idealized length ratio suggesting unidentified constraints or selective pressures.
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Affiliation(s)
- Nihav Dhawale
- Department of Evolution, Ecology and Organismal Biology, UC Riverside , Riverside, CA, USA
| | - David Labonte
- Department of Bioengineering, Imperial College London , London, UK
| | - Natalie C Holt
- Department of Evolution, Ecology and Organismal Biology, UC Riverside , Riverside, CA, USA
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Rode C, Tomalka A, Blickhan R, Siebert T. Structurally motivated models to explain the muscle's force-length relationship. Biophys J 2023; 122:3541-3543. [PMID: 37279747 PMCID: PMC10502428 DOI: 10.1016/j.bpj.2023.05.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 05/10/2023] [Accepted: 05/19/2023] [Indexed: 06/08/2023] Open
Affiliation(s)
- Christian Rode
- Institute of Sport Science, Department of Biomechanics, University of Rostock, Rostock, Germany.
| | - André Tomalka
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany
| | - Reinhard Blickhan
- Institute of Sport Science, Friedrich-Schiller-University Jena, Jena, Germany
| | - Tobias Siebert
- Motion and Exercise Science, University of Stuttgart, Stuttgart, Germany; Stuttgart Center of Simulation Science, University of Stuttgart, Stuttgart, Germany
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Rockenfeller R, Günther M, Hooper SL. Sarcomere mechanics in the double-actin-overlap zone. Biophys J 2023; 122:3544-3548. [PMID: 37582376 PMCID: PMC10502458 DOI: 10.1016/j.bpj.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 08/01/2023] [Accepted: 08/02/2023] [Indexed: 08/17/2023] Open
Affiliation(s)
| | - Michael Günther
- Biomechanics and Biorobotics, Stuttgart Center for Simulation Sciences (SC SimTech), Universität Stuttgart, Stuttgart, Germany; Friedrich-Schiller-Universität, Jena, Germany
| | - Scott L Hooper
- Neuroscience Program, Department of Biological Sciences, Ohio University, Athens, Ohio
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Raiteri BJ, Lauret L, Hahn D. The force-length relation of the young adult human tibialis anterior. PeerJ 2023; 11:e15693. [PMID: 37461407 PMCID: PMC10350298 DOI: 10.7717/peerj.15693] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Accepted: 06/14/2023] [Indexed: 07/20/2023] Open
Abstract
Background Knowledge of the muscle's lengths at which maximum active isometric force is attained is important for predicting forces during movement. However, there is limited information about the in vivo force-length properties of a human muscle that plays crucial roles during locomotion; the tibialis anterior (TA). We therefore aimed to estimate TA's force-length relation from dorsiflexor torque-angle curves constructed from eight women and eight men. Methods Participants performed maximal voluntary fixed-end contractions with their right ankle dorsiflexors from 0° to 30° plantar flexion. Muscle fascicle lengths were estimated from B-mode ultrasound images, and net ankle joint torques were measured using dynamometry. Fascicle forces were estimated by dividing maximal active torques by literature-derived, angle-specific tendon moment arm lengths while assuming a fixed 50% force contribution of TA to the total dorsiflexor force and accounting for fascicle angles. Results Maximal active torques were higher at 15° than 20° and 30° plantar flexion (2.4-6.4 Nm, p ≤ 0.012), whereas maximal active TA fascicle forces were higher at 15° than 0°, 20° and 30° plantar flexion (25-61 N, p ≤ 0.042), but not different between 15° and 10° plantar flexion (15 N, p = 0.277). TA fascicle shortening magnitudes during fixed-end contractions were larger at 15° than 30° plantar flexion (3.9 mm, p = 0.012), but less at 15° than 0° plantar flexion (-2.4 mm, p = 0.001), with no significant differences (≤0.7 mm, p = 0.871) between TA's superficial and deep muscle compartments. Series elastic element stiffness was lowest and highest at lengths 5% shorter and 5% longer than optimum fascicle length, respectively (-30 and 15 N/mm, p ≤ 0.003). Discussion TA produced its maximum active force at 10-15° plantar flexion, and its normalized force-length relation had ascending and descending limbs that agreed with a simple scaled sarcomere model when active fascicle lengths from within TA's superficial or deep muscle compartment were considered. These findings can be used to inform the properties of the contractile and series elastic elements of Hill-type muscle models.
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Affiliation(s)
- Brent J. Raiteri
- Human Movement Science, Faculty of Sport Science, Ruhr-Universität Bochum, Bochum, Nordrhein-Westfalen, Germany
| | - Leon Lauret
- Human Movement Science, Faculty of Sport Science, Ruhr-Universität Bochum, Bochum, Nordrhein-Westfalen, Germany
| | - Daniel Hahn
- Human Movement Science, Faculty of Sport Science, Ruhr-Universität Bochum, Bochum, Nordrhein-Westfalen, Germany
- School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Queensland, Australia
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Labonte D. A theory of physiological similarity in muscle-driven motion. Proc Natl Acad Sci U S A 2023; 120:e2221217120. [PMID: 37285395 PMCID: PMC10268211 DOI: 10.1073/pnas.2221217120] [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: 12/16/2022] [Accepted: 05/02/2023] [Indexed: 06/09/2023] Open
Abstract
Muscle contraction is the primary source of all animal movement. I show that the maximum mechanical output of such contractions is determined by a characteristic dimensionless number, the "effective inertia," Γ, defined by a small set of mechanical, physiological, and anatomical properties of the interrogated musculoskeletal complex. Different musculoskeletal systems with equal Γ may be considered physiologically similar, in the sense that maximum performance involves equal fractions of the muscle's maximum strain rate, strain capacity, work, and power density. It can be demonstrated that there exists a unique, "optimal" musculoskeletal anatomy which enables a unit volume of muscle to deliver maximum work and power simultaneously, corresponding to Γ close to unity. External forces truncate the mechanical performance space accessible to muscle by introducing parasitic losses, and subtly alter how musculoskeletal anatomy modulates muscle performance, challenging canonical notions of skeletal force-velocity trade-offs. Γ varies systematically under isogeometric transformations of musculoskeletal systems, a result which provides fundamental insights into the key determinants of animal locomotor performance across scales.
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Affiliation(s)
- David Labonte
- Evolutionary Biomechanics Laboratory, Department of Bioengineering, Imperial College London, LondonSW7 2BX, United Kingdom
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Han K, Ma S, Sun J, Xu M, Qi X, Wang S, Li L, Li X. In silico modeling of patient-specific blood rheology in type 2 diabetes mellitus. Biophys J 2023; 122:1445-1458. [PMID: 36905122 PMCID: PMC10147843 DOI: 10.1016/j.bpj.2023.03.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 11/16/2022] [Accepted: 03/06/2023] [Indexed: 03/11/2023] Open
Abstract
Increased blood viscosity in type 2 diabetes mellitus (T2DM) is a risk factor for the development of insulin resistance and diabetes-related vascular complications; however, individuals with T2DM exhibit heterogeneous hemorheological properties, including cell deformation and aggregation. Using a multiscale red blood cell (RBC) model with key parameters derived from patient-specific data, we present a computational study of the rheological properties of blood from individual patients with T2DM. Specifically, one key model parameter, which determines the shear stiffness of the RBC membrane (μ) is informed by the high-shear-rate blood viscosity of patients with T2DM. At the same time, the other, which contributes to the strength of the RBC aggregation interaction (D0), is derived from the low-shear-rate blood viscosity of patients with T2DM. The T2DM RBC suspensions are simulated at different shear rates, and the predicted blood viscosity is compared with clinical laboratory-measured data. The results show that the blood viscosity obtained from clinical laboratories and computational simulations are in agreement at both low and high shear rates. These quantitative simulation results demonstrate that the patient-specific model has truly learned the rheological behavior of T2DM blood by unifying the mechanical and aggregation factors of the RBCs, which provides an effective way to extract quantitative predictions of the rheological properties of the blood of individual patients with T2DM.
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Affiliation(s)
- Keqin Han
- State Key Laboratory of Fluid Power and Mechatronic Systems, Department of Engineering Mechanics, and Center for X-Mechanics, Zhejiang University, Hangzhou, China
| | - Shuhao Ma
- State Key Laboratory of Fluid Power and Mechatronic Systems, Department of Engineering Mechanics, and Center for X-Mechanics, Zhejiang University, Hangzhou, China
| | - Jiehui Sun
- Department of Endocrinology and Metabolism, Ningbo First Hospital, Ningbo, China
| | - Miao Xu
- Department of Endocrinology and Metabolism, Ningbo First Hospital, Ningbo, China
| | - Xiaojing Qi
- State Key Laboratory of Fluid Power and Mechatronic Systems, Department of Engineering Mechanics, and Center for X-Mechanics, Zhejiang University, Hangzhou, China
| | - Shuo Wang
- State Key Laboratory of Fluid Power and Mechatronic Systems, Department of Engineering Mechanics, and Center for X-Mechanics, Zhejiang University, Hangzhou, China
| | - Li Li
- Department of Endocrinology and Metabolism, Ningbo First Hospital, Ningbo, China.
| | - Xuejin Li
- State Key Laboratory of Fluid Power and Mechatronic Systems, Department of Engineering Mechanics, and Center for X-Mechanics, Zhejiang University, Hangzhou, China; The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, China.
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Püffel F, Johnston R, Labonte D. A biomechanical model for the relation between bite force and mandibular opening angle in arthropods. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221066. [PMID: 36816849 PMCID: PMC9929505 DOI: 10.1098/rsos.221066] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Accepted: 01/18/2023] [Indexed: 06/18/2023]
Abstract
Bite forces play a key role in animal ecology: they affect mating behaviour, fighting success, and the ability to feed. Although feeding habits of arthropods have a significant ecological and economical impact, we lack fundamental knowledge on how the morphology and physiology of their bite apparatus controls bite performance, and its variation with mandible gape. To address this gap, we derived a biomechanical model that characterizes the relationship between bite force and mandibular opening angle from first principles. We validate this model by comparing its geometric predictions with morphological measurements on the muscoloskeletal bite apparatus of Atta cephalotes leaf-cutter ants, using computed tomography (CT) scans obtained at different mandible opening angles. We then demonstrate its deductive and inductive utility with three examplary use cases: Firstly, we extract the physiological properties of the leaf-cutter ant mandible closer muscle from in vivo bite force measurements. Secondly, we show that leaf-cutter ants are specialized to generate extraordinarily large bite forces, equivalent to about 2600 times their body weight. Thirdly, we discuss the relative importance of morphology and physiology in determining the magnitude and variation of bite force. We hope that a more detailed quantitative understanding of the link between morphology, physiology, and bite performance will facilitate future comparative studies on the insect bite apparatus, and help to advance our knowledge of the behaviour, ecology and evolution of arthropods.
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Affiliation(s)
- Frederik Püffel
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
| | - Richard Johnston
- School of Engineering, Materials Research Centre, Swansea University, Swansea SA2 8PP, UK
| | - David Labonte
- Department of Bioengineering, Imperial College London, London SW7 2AZ, UK
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Campbell KS. An expanding explanation for the ascending limb of muscle's active force-length relationship. Biophys J 2022; 121:1787-1788. [PMID: 35460598 PMCID: PMC9199088 DOI: 10.1016/j.bpj.2022.04.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 03/16/2022] [Accepted: 04/08/2022] [Indexed: 11/19/2022] Open
Affiliation(s)
- Kenneth S Campbell
- Department of Physiology and Division of Cardiovascular Medicine, University of Kentucky, Lexington, Kentucky.
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