Key result
Increasing sarcomere length reversibly shifted the steady-state force-pCa curves for both fast- and slow-twitch rat muscle fibers toward lower Ca(2+) concentrations without affecting curve steepness.
Population
Mechanically skinned fibres of fast-twitch and slow-twitch rat skeletal muscle
Design
Preclinical
Authors
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Distinct Ca²⁺ sensitivities in rat fast- versus slow-twitch fibers persist across lengths and temperatures; leaves open translation to human cardiac muscle.
The sensitivity of the contractile apparatus to Ca2+ increases with increasing sarcomere length in both fast- and slow-twitch rat skeletal muscle fibers.
Stephenson et al. (1982) studied this question. Varied sarcomere lengths and temperatures was evaluated on Steady-state force-pCa relations. Increasing sarcomere length reversibly shifted the steady-state force-pCa curves for both fast- and slow-twitch rat muscle fibers toward lower Ca(2+) concentrations without affecting curve steepness.
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