Insights into the kinetics of Ca2+-regulated contraction and relaxation from myofibril studies |
| |
Authors: | Robert Stehle Johannes Solzin Bogdan Iorga Corrado Poggesi |
| |
Institution: | (1) Institute of Physiology, University of Cologne, Robert Koch Str. 39, 50931 Cologne, Germany;(2) Centre for Molecular Medicine of Cologne, Cologne, 50931, Germany;(3) Department of Physics and Applied Mathematics, Faculty of Chemistry, University of Bucharest, 030018 Bucharest, Romania;(4) Dipartimento di Scienze Fisiologiche, Università di Firenze, Viale Morgagni 63, 50134 Firenze, Italy |
| |
Abstract: | Muscle contraction results from force-generating interactions between myosin cross-bridges on the thick filament and actin
on the thin filament. The force-generating interactions are regulated by Ca2+ via specialised proteins of the thin filament. It is controversial how the contractile and regulatory systems dynamically
interact to determine the time course of muscle contraction and relaxation. Whereas kinetics of Ca2+-induced thin-filament regulation is often investigated with isolated proteins, force kinetics is usually studied in muscle
fibres. The gap between studies on isolated proteins and structured fibres is now bridged by recent techniques that analyse
the chemical and mechanical kinetics of small components of a muscle fibre, subcellular myofibrils isolated from skeletal
and cardiac muscle. Formed of serially arranged repeating units called sarcomeres, myofibrils have a complete fully structured
ensemble of contractile and Ca2+ regulatory proteins. The small diameter of myofibrils (few micrometres) facilitates analysis of the kinetics of sarcomere
contraction and relaxation induced by rapid changes of ATP] or Ca2+]. Among the processes studied on myofibrils are: (1) the Ca2+-regulated switch on/off of the troponin complex, (2) the chemical steps in the cross-bridge adenosine triphosphatase cycle,
(3) the mechanics of force generation and (4) the length dynamics of individual sarcomeres. These studies give new insights
into the kinetics of thin-filament regulation and of cross-bridge turnover, how cross-bridges transform chemical energy into
mechanical work, and suggest that the cross-bridge ensembles of each half-sarcomere cooperate with each other across the half-sarcomere
borders. Additionally, we now have a better understanding of muscle relaxation and its impairment in certain muscle diseases. |
| |
Keywords: | Muscle contraction Muscle relaxation Myocardial contraction Myocardial relaxation Myofibrils Sarcomeres Calcium Thin-filament regulation Cross-bridge kinetics Relaxation Cross-bridge Muscle mechanics Cardiac sarcomere Cardiac muscle Cardiac function Caged calcium Calcium regulation Skinned fibre |
本文献已被 SpringerLink 等数据库收录! |
|