Possible Contribution of Titin Filaments to the Compliant Series Elastic Component in Horseshoe Crab Skeletal Muscle Fibers
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In horseshoe crab skeletal muscle fibers, the extension of SEC at the maximum isometric force P 0 is about 6% of the slack fiber length L 0 (sarcomere length, 7 μm), i.e., about 210 nm per half-sarcomere, being too large to be explained by the cross-bridge and the thin filament elasticities. Cinematographic studies of isometrically contracting myofibril bundes indicate that the highly compliant SEC mostly originates from the “elastic” thick filament misalignment in each A-band during isometric force generation. Possible contribution of the titin filaments to the “elastic” thick filament misalignment is discussed.
KeywordsThin Filament Isometric Force Horseshoe Crab Sarcomere Length Thick Filament
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