Calcium, cross-bridges, and the Frank-Starling relationship.
The steep relationship between active force and length in cardiac muscle is based on a length dependence of myofilament Ca(2+) sensitivity. However, it is not muscle length but the lateral spacing between actin and myosin filaments that sets the level of Ca(2+) sensitivity, mainly through modulation of myosin-mediated activation of the thin filament.
Fuchs
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Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
Smith
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SH
D008841:Actin Cytoskeleton / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism; D009206:Myocardium / Q000166:cytology / Q000378:metabolism
D003432:Cross-Linking Reagents; D002118:Calcium