Sarcomere dynamics during muscular contraction and their implications to muscle function
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This article attempts to identify the key aspects of sarcomere inhomogeneity and the dynamics of sarcomere length changes in muscle contraction experiments and focuses on understanding the mechanics of myofibrils or muscle fibres when viewed as independent units of biological motors (the half-sarcomeres) connected in series. Muscle force generation has been interpreted traditionally on the basis of the kinetics of crossbridge cycling, i.e. binding of myosin heads to actin and consecutive force generating conformational change of the head, under controlled conditions and assuming uniformity of sarcomere or half-sarcomere behaviour. However, several studies have shown that re-distribution of internal strain within myofibrils and muscle fibres may be a key player, particularly, during stretch or relaxation so that force kinetics parameters are strongly affected by sarcomere dynamics. Here, we aim to shed light on how force generation, crossbridge kinetics, and the complex sarcomere movements are to be linked and which mechanical concepts are necessary to develop a comprehensive contraction model of a myofibril.
KeywordsInhomogeneity Myofibril mechanics Half-sarcomere Relaxation
The authors are grateful to KW Ranatunga (Bristol) and Robert Stehle (Cologne) for valuable suggestions on the manuscript, and to the reviewers of this article for constructive comments.
- Danuser G (1997) Quantitative stereo vision for the stereo light microscope. Dissertation, ETH ZurichGoogle Scholar
- Galler S, Hopflinger MC, Andruchov O, Andruchova O, Grassberger H (2005) Effects of vanadate, phosphate and 2,3-butanedione monoxime (BDM) on skinned molluscan catch muscle. Pflugers Arch 449(4):372–383Google Scholar
- Hill AV (1970) First and last experiments in muscle mechanics. Cambridge University Press, LondonGoogle Scholar
- Huxley AF (1957) Muscle structure and theories of contraction. Prog Biophys Mol Biol 7:255–318Google Scholar
- Huxley AF, Lombardi V, Peachey LD (1981) A system for fast recording of longitudinal displacement of a striated muscle fiber. J Physiol 317:12–13PGoogle Scholar
- Huxley AF, Simmons RM (1973) Mechanical transients and origin of muscular force. Cold Spring Harb Symp Quant Biol 37:669–680Google Scholar
- Obermann WM, Gautel M, Steiner F, van der Ven PF, Weber K, Furst DO (1996) The structure of the sarcomeric M band: localization of defined domains of myomesin, M-protein, and the 250-kD carboxy-terminal region of titin by immunoelectron microscopy. J Cell Biol 134:1441–1453PubMedCrossRefGoogle Scholar
- Pinniger GJ, Bruton JD, Westerblad H, Ranatunga KW (2005) Effects of a myosin-II inhibitor (N-benzyl-p-toluene sulphonamide, BTS) on contractile characteristics of intact fast-twitch mammalian muscle fibres. J Muscle Res Cell Motil 26(2–3):135–141Google Scholar
- Rassier DE, Herzog W, Pollack GH (2003b) Stretch-induced force enhancement and stability of skeletal muscle myofibrils. Adv Exp Med Biol 538: 501–515; discussion 515Google Scholar
- Stehle R, Krüger M, Scherer P, Brixius K, Schwinger RH, Pfitzer G (2002b) Isometric force kinetics upon rapid activation and relaxation of mouse, guinea pig and human heart muscle studied on the subcellular myofibrillar level. Basic Res Cardiol 97(Suppl 1):127–135Google Scholar
- Sugi H, Tsuchiya T (1998) Muscle mechanics I: intact single muscle fibres. In: Sugi H (ed) Current methods in muscle physiology: advantages, problems and limitations, 1st edn. Oxford University Press, New YorkGoogle Scholar