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Z disc expansion during supercontraction: a passive mechanism?
Journal of Muscle Research and Cell Motility
|June 1, 1980
Summary
Active Z disc expansion during muscle supercontraction is unlikely. A passive mechanism, dependent on Z disc mechanical continuity, is proposed based on new evidence from blowfly muscles.
Area of Science:
- Muscle physiology
- Sarcomere structure
- Biomechanical analysis
Background:
- Previous studies suggested active Z disc expansion during muscle supercontraction.
- This hypothesis requires re-examination in different muscle preparations.
Purpose of the Study:
- To re-evaluate the hypothesis of active Z disc expansion during muscle supercontraction.
- To investigate the mechanism underlying Z disc behavior during muscle contraction.
Main Methods:
- Experiments were conducted on larval blowfly body-wall muscles.
- Studies included glycerinated supercontracting fibers, whole fibers stimulated to contract, and skinned muscle fibers.
- Theoretical considerations were also incorporated.
Main Results:
- Previous findings on glycerinated fibers were confirmed.
- Observations on whole and skinned fibers, along with theoretical analysis, did not support active Z disc expansion.
- A passive mechanism for Z disc behavior was postulated.
Conclusions:
- The hypothesis of active Z disc expansion during supercontraction is not supported.
- A passive mechanism, reliant on the mechanical continuity of Z discs across the fiber, is proposed.
- This finding offers a new perspective on sarcomere mechanics during muscle contraction.