Key result
In isolated dog hearts, instantaneous fiber shortening velocity (dL/dt) was dependent on instantaneous force and length, varying with contractile state altered by norepinephrine or propranolol.
Population
Seven servo-regulated isolated dog hearts
Comparison
Norepinephrine or propranolol to alter inotropic… vs Different contractile states and initial lengths
Design
Preclinical
Authors
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Does not alter clinical contractility assessment; leaves open translation of force-length-velocity relations to intact human hearts.
The trajectory describing instantaneous force, velocity, and length provides a useful description of the mechanical behavior and contractile state of the ventricular myocardium.
Weber et al. (1977) studied Isolated dog heart (n=7). Norepinephrine or propranolol vs. Baseline/steady-state response was evaluated on Instantaneous mural force, mid-wall circumferential fiber shortening velocity (dL/dt), and fiber length (L). In isolated dog hearts, instantaneous fiber shortening velocity (dL/dt) was dependent on instantaneous force and length, varying with contractile state altered by norepinephrine or propranolol.
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