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Mechanical strain memory in airway smooth muscle
W L Chan1, J Silberstein, C M Hai
1Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, Rhode Island 02912, USA.
American Journal of Physiology. Cell Physiology
|May 4, 2000
Summary
Activated airway smooth muscle cells remember past strain. Rapid stretching with high stress leads to a force and myosin phosphorylation memory in tracheal smooth muscle.
Area of Science:
- Physiology
- Muscle Biology
- Biophysics
Background:
- Smooth muscle force generation is regulated by myosin phosphorylation.
- Airway smooth muscle's response to mechanical stimuli is crucial for respiratory function.
Purpose of the Study:
- To investigate the effect of rapid stretch on poststretch force and myosin phosphorylation in bovine tracheal smooth muscle.
- To determine if activated airway smooth muscle retains a memory of past strain.
Main Methods:
- Muscle strips were subjected to rapid stretches from suboptimal to optimal length (L(o)).
- Force and myosin phosphorylation levels were measured.
- Muscle strips were also subjected to incremental stretches and repeated contraction-relaxation cycles.
Main Results:
- Unstimulated muscle showed no significant difference in poststretch force.
- Activated muscle showed reduced poststretch force and myosin phosphorylation, correlated with initial length.
- Incremental stretching and repeated cycles increased force and phosphorylation, approaching control levels.
Conclusions:
- Activated airway smooth muscle cells exhibit a memory of past strain when subjected to rapid stretch with high stress.
- This memory influences poststretch force and myosin phosphorylation.
- The degree of memory is dependent on the strain history and stress experienced by the muscle.