Abstract
Force-velocity relations, myosin heavy chain (MHC) and myosin light chain (MLC) isoform composition of single skinned fibres from rat plantaris muscle were determined. In fibres containing the same (2X) isoform of myosin heavy chain, several parameters derived from the force-velocity relation and isometric force (Po) were tested for relation with the fibre content in alkali myosin light chain (MLC) isoforms. Whereas maximum shortening velocity was found to be proportional to the relative content in the 3f isoform of alkali MLC, velocity of shortening at 5% relative load, maximum power output, and Po were not. These results strengthen the idea that, in mammalian skeletal fibres, alkali MLC isoforms modulate shortening velocity at zero load, but suggest that they do not control the contractile behaviour at loads higher than zero.
References
Bottinelli R, Schiaffino S, Reggiani, C (1991) Force-velocity relations and myosin heavy chain isoform compositions of skinned fibres from rat skeletal muscle. J Physiol 437:655–672.
Bottinelli R, Betto R, Shiaffino S, Reggiani C (1994) Unloaded shortening velocity and myosin heavy chain and alkali light chain isoform composition in rat skeletal muscle fibres. J Physiol (in the press).
Bottinelli R, Canepari M, Reggiani C, Stienen GJM (1994) Myofibrillar ATPase activity during isometric contraction and isomyosin composition in rat single skinned muscle fibres. J Physiol (in the press).
Josephson RK, Edman KAP (1988) The consequences of fibre heterogeneity on the force-velocity relation of skeletal muscle. Acta Physiol Scand 132:341–352.
Rayment I, Wojciech R, Rypniewski R, Schmidt-Base K, Smith R, Tomchick DR, Benning MM, Winkelmann DA, Wesenberg G, Holden HM (1993) Three-dimensional structure of myosin subfragment-1: a molecular motor, Science 261, 50–58.
Rome LC, Funke RP, Mc Neill Alexander R, Lutz G, Aldridge H, Scott F, Freadman M (1988) Why animals have different muscle fibre types. Nature 335:824–827.
Seow CY, Ford LE (1992) Contribution of damped passive recoil to the measured shortening velocity of skinned rabbit and sheep fibres. J Muscle Res Cell Mot 13:295–307.
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Bottinelli, R., Reggiani, C. Force-velocity properties and myosin light chain isoform composition of an identified type of skinned fibres from rat skeletal muscle. Pflügers Arch. 429, 592–594 (1995). https://doi.org/10.1007/BF00704166
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DOI: https://doi.org/10.1007/BF00704166