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Isolating Myofibrils from Skeletal Muscle Biopsies and Determining Contractile Function with a Nano-Newton Resolution Force Transducer
Published on: May 7, 2020
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Residual force depression in cardiac myofibrils
Seong-Won Han1, Torri Heiser2, Venus Joumaa2
1Department of Cellular and Molecular Medicine, University of Arizona, United States.
Journal of Biomechanics
|March 23, 2025
Summary
Residual force depression (rFD) was observed in cardiac myofibrils, a history-dependent property previously seen only in skeletal muscle. This finding suggests cardiac rFD originates from sarcomere mechanisms.
Area of Science:
- Cardiovascular Physiology
- Muscle Physiology
- Biophysics
Background:
- History-dependent properties, like residual force depression (rFD), are well-documented in skeletal muscle.
- Limited and controversial data exist regarding similar properties in cardiac muscle, with rFD unexplored.
Purpose of the Study:
- To investigate the presence and characteristics of residual force depression (rFD) in cardiac myofibrils.
- To determine if rFD occurs in cardiac muscle under physiologically relevant conditions.
Main Methods:
- Isolated rabbit left ventricular myofibrils (n=10) were studied.
- Myofibrils underwent controlled active shortening from 2.2 µm to 1.8 µm sarcomere length (SL), followed by a recovery period.
- Residual force depression was quantified by comparing steady-state force after shortening to a purely isometric contraction at 1.8 µm SL.
Main Results:
- All ten cardiac myofibrils exhibited residual force depression (rFD).
- The average rFD was 23.0% (± 9.4%) of the purely isometric reference force.
- This indicates rFD is a functional property of cardiac muscle.
Conclusions:
- Residual force depression (rFD) occurs in cardiac muscle myofibrils.
- Cardiac rFD appears to involve sarcomeric mechanisms, similar to skeletal muscle.
- This study establishes rFD as a relevant phenomenon in cardiac muscle physiology.
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