The relation between calcium and contraction kinetics in skinned muscle fibres.
R. J. Podolsky,L. E. Teichholz +1 more
TLDR
Segments of skinned frog muscle fibres were immersed in solutions in which the calcium ion concentration, and therefore the steady isometric force, was controlled with an EGTA buffer system.Abstract:
1. Segments of skinned frog muscle fibres were immersed in solutions in which the calcium ion concentration, and therefore the steady isometric force, was controlled with an EGTA buffer system. The contraction kinetics were measured when the load was quickly reduced to values less than the isometric force.
2. The velocity of shortening following release from steady force was a hyperbolic function of relative load. The minimum quick displacement required to reduce the force from the steady isometric value to half this value was about 1% of the fibre segment length.
3. The relative force—velocity relation was independent of pCa in the range 5·0-6·75. Thus calcium ions appear to control the number of sites at which cross-bridges can be formed but have no significant effect on the kinetic properties of an individual bridge.
4. Cross-bridges along the length of a myofilament appear to act independently of each other.
5. The force—velocity relations reported for intact muscle fibres during relaxation, when compared with those of skinned fibres at different calcium levels, indicate that the time course of the fall in force after a stimulus is essentially that of calcium removal from the myofilaments.read more
Citations
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Journal ArticleDOI
Dynamic properties of mammalian skeletal muscles.
TL;DR: The author examines the relationship between ATPase activity of myosin and intrinsic speed of shortening, and the effects of nerve cross-union on properties of myOSin.
Journal ArticleDOI
Regulation of Contraction in Striated Muscle
TL;DR: Ca(2+) regulation of contraction in vertebrate striated muscle is exerted primarily through effects on the thin filament, which regulate strong cross-bridge binding to actin, and the physiological observations of steady-state and transient mechanical behavior are supported.
Journal ArticleDOI
The velocity of unloaded shortening and its relation to sarcomere length and isometric force in vertebrate muscle fibres.
TL;DR: The velocity of shortening at zero load was studied during fused tetanic contractions and single twitches in isolated skeletal muscle fibres of Rana temporaria and the technique used for determination of the speed of unloaded shortening consisted of a series of quick releases of different amplitudes applied at a given instant during activity.
Journal ArticleDOI
Theoretical formalism for the sliding filament model of contraction of striated muscle Part I
Journal ArticleDOI
The effect of phosphate and calcium on force generation in glycerinated rabbit skeletal muscle fibers. A steady-state and transient kinetic study.
N C Millar,Earl Homsher +1 more
TL;DR: Steady-state results show that the three parameters that define the force-pCa relation all vary linearly with log [Pi], and can be interpreted in terms of a model in which strong cross-bridges activate the thin filament, this activation being modulated by Ca2+ binding to troponin.
References
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The variation in isometric tension with sarcomere length in vertebrate muscle fibres.
TL;DR: The variation of isometric tetanus tension with sarcomere length in single fibres from frog striated muscle has been re‐investigated with special precautions to ensure uniformity of sarcomeres length within the part of the fibre being studied.
Journal ArticleDOI
An analysis of the mechanical components in frog's striated muscle.
B. R. Jewell,D. R. Wilkie +1 more
TL;DR: J. R. Wilkie striated muscle An analysis of the mechanical components in frog's This information is current as of March 19, 2008 and has been published is the official journal of The Journal of Physiology Online.