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Asiri F, Haque Siddiqui MI, Ali MA, Alam T, Dobrotă D, Chicea R, Dobrotă RD. Mathematical modeling of active contraction of the human cardiac myocyte: A review. Heliyon 2023; 9:e20065. [PMID: 37809539 PMCID: PMC10559823 DOI: 10.1016/j.heliyon.2023.e20065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 08/26/2023] [Accepted: 09/10/2023] [Indexed: 10/10/2023] Open
Abstract
Background and objective In this present research paper, a mathematical model has been developed to study myocyte contraction in the human cardiac muscle, using the Land model. Different parts of the human heart with a focus on the composition of the myocyte cells have been explored numerically to enabling us to determine the interaction of various parameters in the heart muscle. The main objective of the work is to direct the study of the Land model, which has been exploited to simulate the contraction of real human myocytes. Methods Mathematical models has been developed based on the Hill model and Huxley model. Myocyte contraction for different scenarios, such as in isometric tension and isotonic tension have been studied. Results It is found that increase in stretch, the peak active tension increases, in line with well-established length-dependent tension generation. Five parameters are selected: [Ca2+]T50, Tref, TRPN50, β0, and β1, which have been varied in between the range of -50%-100%, to examine the isometric effects of each parameter on the behavior of the tension developed in the intact myocyte cells, with the most sensitive parameter being [Ca2+]T50. Conclusion In conclusion, it is found that the Land model provides a good platform for the analysis of the active contraction of the human cardiac myocyte.
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Affiliation(s)
- Fisal Asiri
- Department of Mathematics, Taibah University, Medina, 42353, Saudi Arabia
| | | | - Masood Ashraf Ali
- Department of Industrial Engineering, College of Engineering, Prince Sattam Bin Abdulaziz University, Al-Kharj, 16273, Saudi Arabia
| | - Tabish Alam
- CSIR-Central Building Research Institute, Roorkee, 247667, India
| | - Dan Dobrotă
- Faculty of Engineering, Lucian Blaga University of Sibiu, 550024, Sibiu, Romania
| | - Radu Chicea
- Faculty of Medicine, Lucian Blaga University of Sibiu, 550024, Sibiu, Romania
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Han J, Taberner AJ, Loiselle DS, Tran K. Cardiac efficiency and Starling's Law of the Heart. J Physiol 2022; 600:4265-4285. [PMID: 35998082 PMCID: PMC9826111 DOI: 10.1113/jp283632] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 08/18/2022] [Indexed: 01/11/2023] Open
Abstract
The formulation by Starling of The Law of the Heart states that 'the [mechanical] energy of contraction, however measured, is a function of the length of the muscle fibre'. Starling later also stated that 'the oxygen consumption of the isolated heart … is determined by its diastolic volume, and therefore by the initial length of its muscular fibres'. This phrasing has motivated us to extend Starling's Law of the Heart to include consideration of the efficiency of contraction. In this study, we assessed both mechanical efficiency and crossbridge efficiency by studying the heat output of isolated rat ventricular trabeculae performing force-length work-loops over ranges of preload and afterload. The combination of preload and afterload allowed us, using our modelling frameworks for the end-systolic zone and the heat-force zone, to simulate cases by recreating physiologically feasible loading conditions. We found that across all cases examined, both work output and change of enthalpy increased with initial muscle length; hence it can only be that the former increases more than the latter to yield increased mechanical efficiency. In contrast, crossbridge efficiency increased with initial muscle length in cases where the extent of muscle shortening varied greatly with preload. We conclude that the efficiency of cardiac contraction increases with increasing initial muscle length and preload. An implication of our conclusion is that the length-dependent activation mechanism underlying the cellular basis of Starling's Law of the Heart is an energetically favourable process that increases the efficiency of cardiac contraction. KEY POINTS: Ernest Starling in 1914 formulated the Law of the Heart to describe the mechanical property of cardiac muscle whereby force of contraction increases with muscle length. He subsequently, in 1927, showed that the oxygen consumption of the heart is also a function of the length of the muscle fibre, but left the field unclear as to whether cardiac efficiency follows the same dependence. A century later, the field has gained an improved understanding of the factors, including the distinct effects of preload and afterload, that affect cardiac efficiency. This understanding presents an opportunity for us to investigate the elusive length-dependence of cardiac efficiency. We found that, by simulating physiologically feasible loading conditions using a mechano-energetics framework, cardiac efficiency increased with initial muscle length. A broader physiological importance of our findings is that the underlying cellular basis of Starling's Law of the Heart is an energetically favourable process that yields increased efficiency.
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Affiliation(s)
- June‐Chiew Han
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand
| | - Andrew J. Taberner
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand,Department of Engineering ScienceUniversity of AucklandAucklandNew Zealand
| | - Denis S. Loiselle
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand,Department of PhysiologyUniversity of AucklandAucklandNew Zealand
| | - Kenneth Tran
- Auckland Bioengineering InstituteUniversity of AucklandAucklandNew Zealand
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3
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Sharifi H, Mann CK, Rockward AL, Mehri M, Mojumder J, Lee LC, Campbell KS, Wenk JF. Multiscale simulations of left ventricular growth and remodeling. Biophys Rev 2021; 13:729-746. [PMID: 34777616 PMCID: PMC8555068 DOI: 10.1007/s12551-021-00826-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 08/05/2021] [Indexed: 02/07/2023] Open
Abstract
Cardiomyocytes can adapt their size, shape, and orientation in response to altered biomechanical or biochemical stimuli. The process by which the heart undergoes structural changes-affecting both geometry and material properties-in response to altered ventricular loading, altered hormonal levels, or mutant sarcomeric proteins is broadly known as cardiac growth and remodeling (G&R). Although it is likely that cardiac G&R initially occurs as an adaptive response of the heart to the underlying stimuli, prolonged pathological changes can lead to increased risk of atrial fibrillation, heart failure, and sudden death. During the past few decades, computational models have been extensively used to investigate the mechanisms of cardiac G&R, as a complement to experimental measurements. These models have provided an opportunity to quantitatively study the relationships between the underlying stimuli (primarily mechanical) and the adverse outcomes of cardiac G&R, i.e., alterations in ventricular size and function. State-of-the-art computational models have shown promise in predicting the progression of cardiac G&R. However, there are still limitations that need to be addressed in future works to advance the field. In this review, we first outline the current state of computational models of cardiac growth and myofiber remodeling. Then, we discuss the potential limitations of current models of cardiac G&R that need to be addressed before they can be utilized in clinical care. Finally, we briefly discuss the next feasible steps and future directions that could advance the field of cardiac G&R.
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Affiliation(s)
- Hossein Sharifi
- Department of Mechanical Engineering, University of Kentucky, 269 Ralph G. Anderson Building, Lexington, KY 40506-0503 USA
| | - Charles K. Mann
- Department of Mechanical Engineering, University of Kentucky, 269 Ralph G. Anderson Building, Lexington, KY 40506-0503 USA
| | - Alexus L. Rockward
- Department of Mechanical Engineering, University of Kentucky, 269 Ralph G. Anderson Building, Lexington, KY 40506-0503 USA
| | - Mohammad Mehri
- Department of Mechanical Engineering, University of Kentucky, 269 Ralph G. Anderson Building, Lexington, KY 40506-0503 USA
| | - Joy Mojumder
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI USA
| | - Lik-Chuan Lee
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI USA
| | - Kenneth S. Campbell
- Department of Physiology & Division of Cardiovascular Medicine, University of Kentucky, Lexington, KY USA
| | - Jonathan F. Wenk
- Department of Mechanical Engineering, University of Kentucky, 269 Ralph G. Anderson Building, Lexington, KY 40506-0503 USA
- Department of Surgery, University of Kentucky, Lexington, KY USA
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Vander Roest AS, Liu C, Morck MM, Kooiker KB, Jung G, Song D, Dawood A, Jhingran A, Pardon G, Ranjbarvaziri S, Fajardo G, Zhao M, Campbell KS, Pruitt BL, Spudich JA, Ruppel KM, Bernstein D. Hypertrophic cardiomyopathy β-cardiac myosin mutation (P710R) leads to hypercontractility by disrupting super relaxed state. Proc Natl Acad Sci U S A 2021. [PMID: 34117120 DOI: 10.1073/pnas.2025030118/suppl_file/pnas.2025030118.sm02.avi] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is the most common inherited form of heart disease, associated with over 1,000 mutations, many in β-cardiac myosin (MYH7). Molecular studies of myosin with different HCM mutations have revealed a diversity of effects on ATPase and load-sensitive rate of detachment from actin. It has been difficult to predict how such diverse molecular effects combine to influence forces at the cellular level and further influence cellular phenotypes. This study focused on the P710R mutation that dramatically decreased in vitro motility velocity and actin-activated ATPase, in contrast to other MYH7 mutations. Optical trap measurements of single myosin molecules revealed that this mutation reduced the step size of the myosin motor and the load sensitivity of the actin detachment rate. Conversely, this mutation destabilized the super relaxed state in longer, two-headed myosin constructs, freeing more heads to generate force. Micropatterned human induced pluripotent derived stem cell (hiPSC)-cardiomyocytes CRISPR-edited with the P710R mutation produced significantly increased force (measured by traction force microscopy) compared with isogenic control cells. The P710R mutation also caused cardiomyocyte hypertrophy and cytoskeletal remodeling as measured by immunostaining and electron microscopy. Cellular hypertrophy was prevented in the P710R cells by inhibition of ERK or Akt. Finally, we used a computational model that integrated the measured molecular changes to predict the measured traction forces. These results confirm a key role for regulation of the super relaxed state in driving hypercontractility in HCM with the P710R mutation and demonstrate the value of a multiscale approach in revealing key mechanisms of disease.
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Affiliation(s)
- Alison Schroer Vander Roest
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305
- Department of Bioengineering, School of Engineering and School of Medicine, Stanford University, Stanford, CA 94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Chao Liu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Makenna M Morck
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Kristina Bezold Kooiker
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
- School of Medicine, University of Washington, Seattle, WA 98109
| | - Gwanghyun Jung
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Dan Song
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Aminah Dawood
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Arnav Jhingran
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
| | - Gaspard Pardon
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305
- Department of Bioengineering, School of Engineering and School of Medicine, Stanford University, Stanford, CA 94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Sara Ranjbarvaziri
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Giovanni Fajardo
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Mingming Zhao
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Kenneth S Campbell
- Department of Physiology, University of Kentucky, Lexington, KY 40536
- Division of Cardiovascular Medicine, University of Kentucky, Lexington, KY 40536
| | - Beth L Pruitt
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305
- Department of Bioengineering, School of Engineering and School of Medicine, Stanford University, Stanford, CA 94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
- Mechanical and Biomolecular Science and Engineering, University of California, Santa Barbara, CA 93106
| | - James A Spudich
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305;
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Kathleen M Ruppel
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Daniel Bernstein
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304;
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
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5
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Vander Roest AS, Liu C, Morck MM, Kooiker KB, Jung G, Song D, Dawood A, Jhingran A, Pardon G, Ranjbarvaziri S, Fajardo G, Zhao M, Campbell KS, Pruitt BL, Spudich JA, Ruppel KM, Bernstein D. Hypertrophic cardiomyopathy β-cardiac myosin mutation (P710R) leads to hypercontractility by disrupting super relaxed state. Proc Natl Acad Sci U S A 2021; 118:e2025030118. [PMID: 34117120 PMCID: PMC8214707 DOI: 10.1073/pnas.2025030118] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Hypertrophic cardiomyopathy (HCM) is the most common inherited form of heart disease, associated with over 1,000 mutations, many in β-cardiac myosin (MYH7). Molecular studies of myosin with different HCM mutations have revealed a diversity of effects on ATPase and load-sensitive rate of detachment from actin. It has been difficult to predict how such diverse molecular effects combine to influence forces at the cellular level and further influence cellular phenotypes. This study focused on the P710R mutation that dramatically decreased in vitro motility velocity and actin-activated ATPase, in contrast to other MYH7 mutations. Optical trap measurements of single myosin molecules revealed that this mutation reduced the step size of the myosin motor and the load sensitivity of the actin detachment rate. Conversely, this mutation destabilized the super relaxed state in longer, two-headed myosin constructs, freeing more heads to generate force. Micropatterned human induced pluripotent derived stem cell (hiPSC)-cardiomyocytes CRISPR-edited with the P710R mutation produced significantly increased force (measured by traction force microscopy) compared with isogenic control cells. The P710R mutation also caused cardiomyocyte hypertrophy and cytoskeletal remodeling as measured by immunostaining and electron microscopy. Cellular hypertrophy was prevented in the P710R cells by inhibition of ERK or Akt. Finally, we used a computational model that integrated the measured molecular changes to predict the measured traction forces. These results confirm a key role for regulation of the super relaxed state in driving hypercontractility in HCM with the P710R mutation and demonstrate the value of a multiscale approach in revealing key mechanisms of disease.
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Affiliation(s)
- Alison Schroer Vander Roest
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305
- Department of Bioengineering, School of Engineering and School of Medicine, Stanford University, Stanford, CA 94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Chao Liu
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Makenna M Morck
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Kristina Bezold Kooiker
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
- School of Medicine, University of Washington, Seattle, WA 98109
| | - Gwanghyun Jung
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Dan Song
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Aminah Dawood
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Arnav Jhingran
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
| | - Gaspard Pardon
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305
- Department of Bioengineering, School of Engineering and School of Medicine, Stanford University, Stanford, CA 94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Sara Ranjbarvaziri
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Giovanni Fajardo
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Mingming Zhao
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
| | - Kenneth S Campbell
- Department of Physiology, University of Kentucky, Lexington, KY 40536
- Division of Cardiovascular Medicine, University of Kentucky, Lexington, KY 40536
| | - Beth L Pruitt
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305
- Department of Bioengineering, School of Engineering and School of Medicine, Stanford University, Stanford, CA 94305
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
- Mechanical and Biomolecular Science and Engineering, University of California, Santa Barbara, CA 93106
| | - James A Spudich
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305;
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Kathleen M Ruppel
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305
| | - Daniel Bernstein
- Department of Pediatrics (Cardiology), Stanford University School of Medicine, Palo Alto, CA 94304;
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Stanford, CA 94305
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6
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Powers JD, Malingen SA, Regnier M, Daniel TL. The Sliding Filament Theory Since Andrew Huxley: Multiscale and Multidisciplinary Muscle Research. Annu Rev Biophys 2021; 50:373-400. [PMID: 33637009 DOI: 10.1146/annurev-biophys-110320-062613] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Two groundbreaking papers published in 1954 laid out the theory of the mechanism of muscle contraction based on force-generating interactions between myofilaments in the sarcomere that cause filaments to slide past one another during muscle contraction. The succeeding decades of research in muscle physiology have revealed a unifying interest: to understand the multiscale processes-from atom to organ-that govern muscle function. Such an understanding would have profound consequences for a vast array of applications, from developing new biomimetic technologies to treating heart disease. However, connecting structural and functional properties that are relevant at one spatiotemporal scale to those that are relevant at other scales remains a great challenge. Through a lens of multiscale dynamics, we review in this article current and historical research in muscle physiology sparked by the sliding filament theory.
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Affiliation(s)
- Joseph D Powers
- Department of Bioengineering, University of California San Diego, La Jolla, California 92093, USA
| | - Sage A Malingen
- Department of Biology, University of Washington, Seattle, Washington 98195, USA;
| | - Michael Regnier
- Department of Bioengineering, University of Washington, Seattle, Washington 98185, USA
- Center for Translational Muscle Research, University of Washington, Seattle, Washington 98185, USA
| | - Thomas L Daniel
- Department of Biology, University of Washington, Seattle, Washington 98195, USA;
- Department of Bioengineering, University of Washington, Seattle, Washington 98185, USA
- Center for Translational Muscle Research, University of Washington, Seattle, Washington 98185, USA
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Blum KP, Campbell KS, Horslen BC, Nardelli P, Housley SN, Cope TC, Ting LH. Diverse and complex muscle spindle afferent firing properties emerge from multiscale muscle mechanics. eLife 2020; 9:e55177. [PMID: 33370235 PMCID: PMC7769569 DOI: 10.7554/elife.55177] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 12/04/2020] [Indexed: 11/13/2022] Open
Abstract
Despite decades of research, we lack a mechanistic framework capable of predicting how movement-related signals are transformed into the diversity of muscle spindle afferent firing patterns observed experimentally, particularly in naturalistic behaviors. Here, a biophysical model demonstrates that well-known firing characteristics of mammalian muscle spindle Ia afferents - including movement history dependence, and nonlinear scaling with muscle stretch velocity - emerge from first principles of muscle contractile mechanics. Further, mechanical interactions of the muscle spindle with muscle-tendon dynamics reveal how motor commands to the muscle (alpha drive) versus muscle spindle (gamma drive) can cause highly variable and complex activity during active muscle contraction and muscle stretch that defy simple explanation. Depending on the neuromechanical conditions, the muscle spindle model output appears to 'encode' aspects of muscle force, yank, length, stiffness, velocity, and/or acceleration, providing an extendable, multiscale, biophysical framework for understanding and predicting proprioceptive sensory signals in health and disease.
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Affiliation(s)
- Kyle P Blum
- Department of Physiology, Feinberg School of Medicine, Northwestern UniversityChicagoUnited States
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of TechnologyAtlantaUnited States
| | | | - Brian C Horslen
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of TechnologyAtlantaUnited States
| | - Paul Nardelli
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Stephen N Housley
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Timothy C Cope
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of TechnologyAtlantaUnited States
- School of Biological Sciences, Georgia Institute of TechnologyAtlantaUnited States
| | - Lena H Ting
- Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of TechnologyAtlantaUnited States
- Department of Rehabilitation Medicine, Emory UniversityAtlantaUnited States
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8
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Campbell KS, Chrisman BS, Campbell SG. Multiscale Modeling of Cardiovascular Function Predicts That the End-Systolic Pressure Volume Relationship Can Be Targeted via Multiple Therapeutic Strategies. Front Physiol 2020; 11:1043. [PMID: 32973561 PMCID: PMC7466769 DOI: 10.3389/fphys.2020.01043] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2019] [Accepted: 07/29/2020] [Indexed: 01/01/2023] Open
Abstract
Most patients who develop heart failure are unable to elevate their cardiac output on demand due to impaired contractility and/or reduced ventricular filling. Despite decades of research, few effective therapies for heart failure have been developed. In part, this may reflect the difficulty of predicting how perturbations to molecular-level mechanisms that are induced by drugs will scale up to modulate system-level properties such as blood pressure. Computer modeling might help with this process and thereby accelerate the development of better therapies for heart failure. This manuscript presents a new multiscale model that uses a single contractile element to drive an idealized ventricle that pumps blood around a closed circulation. The contractile element was formed by linking an existing model of dynamically coupled myofilaments with a well-established model of myocyte electrophysiology. The resulting framework spans from molecular-level events (including opening of ion channels and transitions between different myosin states) to properties such as ejection fraction that can be measured in patients. Initial calculations showed that the model reproduces many aspects of normal cardiovascular physiology including, for example, pressure-volume loops. Subsequent sensitivity tests then quantified how each model parameter influenced a range of system level properties. The first key finding was that the End Systolic Pressure Volume Relationship, a classic index of cardiac contractility, was ∼50% more sensitive to parameter changes than any other system-level property. The second important result was that parameters that primarily affect ventricular filling, such as passive stiffness and Ca2+ reuptake via sarco/endoplasmic reticulum Ca2+-ATPase (SERCA), also have a major impact on systolic properties including stroke work, myosin ATPase, and maximum ventricular pressure. These results reinforce the impact of diastolic function on ventricular performance and identify the End Systolic Pressure Volume Relationship as a particularly sensitive system-level property that can be targeted using multiple therapeutic strategies.
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Affiliation(s)
- Kenneth S Campbell
- Division of Cardiovascular Medicine, Department of Physiology, University of Kentucky, Lexington, KY, United States
| | | | - Stuart G Campbell
- Department of Biomedical Engineering, Yale University, New Haven, CT, United States
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