Calcium in Muscle Activation
Calcium in Muscle Activation

Author: Johann C. Rüegg

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 309

ISBN-13: 364296981X

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This book offers a comparative and interdisciplinary approach to excitation-contraction-coupling in smooth and striated mus cles, including the myocardium. It is an account of the path ways and mechanisms by which cellular calcium is handled and activates the contractile proteins. It also describes how these mechanisms are adapted in various kinds of muscle to meet specific functional requirements, such as speed or economy. This monograph then presents facts, ideas and theories and the evidence on which they are based, and ifit stimulates others and furthers research, it will have served its purpose. All of the chapters are self-contained and may be read in any order, but readers unfamiliar with muscle are recommended to start with the introductory chapter on excitation and contraction. During all the years of writing this book, I received enormous help from Isolde Berger who corrected, edited and transformed my innumerable notes and drafts into a readable manuscript; she also compiled the list of references and the Subject Index. I owe a great debt of gratitude to her and also to Claudia Zeugner, who prepared the figures with expertise and care. Then I would like to thank the Deutsche F orschungs gemeinschaft and the Fritz-Thyssen-Stiftung for supporting the work of my Department which has been reported in this monograph. A great many people contributed with helpful discussions.

A Coupled Electro-Chemical-Mechanical Multi-Scale Computational Framework for Simulation of Skeletal Muscles
A Coupled Electro-Chemical-Mechanical Multi-Scale Computational Framework for Simulation of Skeletal Muscles

Author: Yantao Zhang

Publisher:

Published: 2015

Total Pages: 199

ISBN-13:

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This work focuses on electro-chemical-mechanical multi-scale simulation of the excitation-contraction of skeletal muscle, including electro-chemical excitation process in the neural system which activates the contraction of muscle fibers, the combined effects of active fiber contraction and passive extracellular matrix (ECM) mechanical deformation, and their resulting force generation in the muscle components. In the neural systems, the Fitzhugh-Nagumo (FHN) equation is solved to simulate the propagation of neural signals (action potential) in neural trees and muscle fibers using multi-dimensional FHN discretizations. The calculated neural signal is consequently used as the input for the calcium dynamics model, which describes the chemical processes in the muscle fibers. Based on the calculated calcium concentration, the activation distribution in the muscle tissue is then obtained, which determines the active force muscle fiber can generate voluntarily. To study the mechanics associated with the composition of muscle fibers and ECM, the microstructure of skeletal muscle is reconstructed from images, from which the homogenized material property in the continuum level is calculated. By varying the microstructure model, their morphological effect on the muscle performance is studied and compared with experimental observation. Computationally, the physiological models in excitation dynamics are solved by finite difference methods, and their accuracy, efficiency and stability conditions are studied respectively. For the cellular and component scale models, the 3-dimensional reproducing kernel particle method (RKPM) together with stabilized conforming nodal integration are employed. The simulation models are constructed based on medical images, where the pixel points are directly used as meshfree nodes. This computational model has been used to investigate the source of reduced force generation associated with ageing or diseases within muscles due to the malfunctioning in the subscale units. Through the proposed computational models, this research demonstrates how the stiffened connective tissue reduces force generation and how the frequency of neural stimulation affects force generation in the skeletal muscle.

Excitation-Contraction Coupling and Cardiac Contractile Force
Excitation-Contraction Coupling and Cardiac Contractile Force

Author: Donald Bers

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 468

ISBN-13: 940100658X

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How is the heartbeat generated? What controls the strength of contraction of heart muscle? What are the links between cardiac structure and function? How does our understanding of skeletal and smooth muscle and non-muscle cells influence our thinking about force development in the heart? Are there important species differences in how contraction is regulated in the heart? How do the new molecular data fit together in understanding the heart beat? What goes wrong in ischemia, hypertrophy, and heart failure? This book paints a modern `portrait' of how the heart works and in this picture the author shows a close-up of the structural, biochemical, and physiological links between excitation and contraction. The author takes the reader through a series of important, interrelated topics with great clarity and continuity and also includes many useful illustrations and tables. The book starts by considering the cellular structures involved in excitation-contraction coupling and then described the characteristics of the myofilaments as the end effector of excitation-contraction coupling. A general scheme of calcium regulation is described and the possible sources and sinks of calcium are discussed in simple, but quantitative terms. The cardiac action potential and its many underlying currents are reviewed. Then the characteristics of some key calcium transport systems (calcium channels, sodium/calcium exchange and SR calcium uptake and release) are discussed in detail. This is then built into a more integrated picture of calcium regulation in succeeding chapters by detailed discussions of excitation-calcium coupling mechanisms (in skeletal, cardiac, and smooth muscle), the interplay between calcium regulatory processes, and finally mechanisms of cardiac inotropy, calcium overload, and dysfunction (e.g., ischemia, hypertrophy, and heart failure). Excitation-Contraction Coupling and Cardiac Contractile Force – Second Edition is an invaluable source of information for anyone who is interested in how the heart beat is controlled and especially suited for students of the cardiovascular system at all levels from medical/graduate students through senior investigators in related fields.

Regulating Muscle Contraction
Regulating Muscle Contraction

Author: Milad Webb

Publisher:

Published: 2013

Total Pages: 174

ISBN-13:

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The objective of this dissertation is to characterize the relationship between myosin ATPase kinetics, calcium sensitivity and cooperativity of thin filament activation to explain the role of calcium- and myosin-dependent activation processes observed during muscle contraction. The findings will be extended to a cardiomyocyte system developed to investigate the relationship between myosin kinetics, force generated from the sarcomere, and maladaptive phenotypic changes. Using the in vitro motility assay to simulate unloaded muscle shortening, the effect of inhibition of intermediate states of the myosin ATPase cycle was characterized. We determined that calcium sensitivity and cooperativity were modulated via perturbation of myosin duty ratio. A cardiomyocyte system for mechanical studies was developed to further investigate the role of ATPase kinetics in cardiac remodeling. This system allows for the perturbation of ATPase kinetics, as well as manipulation of various signaling pathways (which can be monitored fluorescently), while monitoring force generated internally and transferred to the extracellular environment, which is critical in the study of hypertrophic phenotypes. Collectively, our findings indicate that targeted therapeutics which modulate myosin ATPase kinetics can normalize calcium sensitivity and cooperativity in compromised cardiac tissue; and these therapeutics can be accurately evaluated and modeled in the in vitro environment.

Store-Operated Calcium Channels
Store-Operated Calcium Channels

Author:

Publisher: Academic Press

Published: 2013-07-24

Total Pages: 307

ISBN-13: 0124079385

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Store-operated calcium channels are found in most animal cells and regulate many cellular functions including cell division, growth, differentiation, and cell death. This volume provides a concise and informative overview of the principles of store-operated calcium entry and the key developments in the field from researchers who have led these advances. The overall goal of the volume is to provide interested students and investigators with sufficient information to enable a broad understanding of the progress and current excitement in the field. The volume contains a wealth of information that even experienced investigators in the field will find useful. The volume provides a comprehensive overview of the mechanisms and functions of store-operated calcium channels Contributors are authoritative researchers who have produced important advances in the field The volume is well-illustrated with cartoons and data to facilitate easy comprehension of the subject

Multiple Muscle Systems
Multiple Muscle Systems

Author: Jack M. Winters

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 818

ISBN-13: 1461390303

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The picture on the front cover of this book depicts a young man pulling a fishnet, a task of practical relevance for many centuries. It is a complex task, involving load transmission throughout the body, intricate balance, and eye head-hand coordination. The quest toward understanding how we perform such tasks with skill and grace, often in the presence of unpredictable pertur bations, has a long history. However, despite a history of magnificent sculptures and drawings of the human body which vividly depict muscle ac tivity and interaction, until more recent times our state of knowledge of human movement was rather primitive. During the past century this has changed; we now have developed a considerable database regarding the com position and basic properties of muscle and nerve tissue and the basic causal relations between neural function and biomechanical movement. Over the last few decades we have also seen an increased appreciation of the impor tance of musculoskeletal biomechanics: the neuromotor system must control movement within a world governed by mechanical laws. We have now col lected quantitative data for a wealth of human movements. Our capacity to understand the data we collect has been enhanced by our continually evolving modeling capabilities and by the availability of computational power. What have we learned? This book is designed to help synthesize our current knowledge regarding the role of muscles in human movement. The study of human movement is not a mature discipline.

Skeletal Muscle Circulation
Skeletal Muscle Circulation

Author: Ronald J. Korthuis

Publisher: Morgan & Claypool Publishers

Published: 2011

Total Pages: 147

ISBN-13: 1615041834

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The aim of this treatise is to summarize the current understanding of the mechanisms for blood flow control to skeletal muscle under resting conditions, how perfusion is elevated (exercise hyperemia) to meet the increased demand for oxygen and other substrates during exercise, mechanisms underlying the beneficial effects of regular physical activity on cardiovascular health, the regulation of transcapillary fluid filtration and protein flux across the microvascular exchange vessels, and the role of changes in the skeletal muscle circulation in pathologic states. Skeletal muscle is unique among organs in that its blood flow can change over a remarkably large range. Compared to blood flow at rest, muscle blood flow can increase by more than 20-fold on average during intense exercise, while perfusion of certain individual white muscles or portions of those muscles can increase by as much as 80-fold. This is compared to maximal increases of 4- to 6-fold in the coronary circulation during exercise. These increases in muscle perfusion are required to meet the enormous demands for oxygen and nutrients by the active muscles. Because of its large mass and the fact that skeletal muscles receive 25% of the cardiac output at rest, sympathetically mediated vasoconstriction in vessels supplying this tissue allows central hemodynamic variables (e.g., blood pressure) to be spared during stresses such as hypovolemic shock. Sympathetic vasoconstriction in skeletal muscle in such pathologic conditions also effectively shunts blood flow away from muscles to tissues that are more sensitive to reductions in their blood supply that might otherwise occur. Again, because of its large mass and percentage of cardiac output directed to skeletal muscle, alterations in blood vessel structure and function with chronic disease (e.g., hypertension) contribute significantly to the pathology of such disorders. Alterations in skeletal muscle vascular resistance and/or in the exchange properties of this vascular bed also modify transcapillary fluid filtration and solute movement across the microvascular barrier to influence muscle function and contribute to disease pathology. Finally, it is clear that exercise training induces an adaptive transformation to a protected phenotype in the vasculature supplying skeletal muscle and other tissues to promote overall cardiovascular health. Table of Contents: Introduction / Anatomy of Skeletal Muscle and Its Vascular Supply / Regulation of Vascular Tone in Skeletal Muscle / Exercise Hyperemia and Regulation of Tissue Oxygenation During Muscular Activity / Microvascular Fluid and Solute Exchange in Skeletal Muscle / Skeletal Muscle Circulation in Aging and Disease States: Protective Effects of Exercise / References