Key result
In cat papillary muscle, increasing initial muscle length increases maximal developed force without changing maximal velocity of shortening, while positive inotropic interventions increase maximal velocity.
Population
Cat papillary muscle
Comparison
Changes in initial muscle length, frequency of… vs Baseline or alternative muscle lengths…
Design
Preclinical
Authors
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Distinguishes preload from inotropic effects on force-velocity relations in isolated muscle; leaves open translation to human ventricular performance.
This foundational physiological study demonstrates that in mammalian cardiac muscle, changes in initial length alter maximal force without affecting maximal shortening velocity, while inotropic interventions increase maximal shortening velocity.
Edmund H. Sonnenblick (1962) studied Force-velocity relations in mammalian heart muscle. Changes in muscle length, frequency of contraction, and chemical environment (calcium, norepinephrine) was evaluated on Force-velocity relations (velocity of shortening and force developed). In cat papillary muscle, increasing initial muscle length increases maximal developed force without changing maximal velocity of shortening, while positive inotropic interventions increase maximal velocity.
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