dorsal/arxiv
View SchemaInstabilities in the transient response of muscle
| Authors | Andrej Vilfan, Thomas Duke |
|---|---|
| Categories | |
| ArXiv ID | physics/0303087 |
| URL | https://arxiv.org/abs/physics/0303087 |
| DOI | 10.1016/S0006-3495(03)74522-6 |
| Journal | Biophys. J. 85, 818-827 (2003) |
Abstract
We investigate the isometric transient response of muscle using a quantitative stochastic model of the actomyosin cycle based on the swinging lever-arm hypothesis. We first consider a single pair of filaments, and show that when values of parameters such as the lever-arm displacement and the crossbridge elasticity are chosen to provide effective energy transduction, the T2 curve (the tension recovered immediately after a step displacement) displays a region of negative slope. If filament compliance and the discrete nature of the binding sites are taken into account, the negative slope is diminished, but not eliminated. This implies that there is an instability in the dynamics of individual half-sarcomeres. However, when the symmetric nature of whole sarcomeres is taken into account, filament rearrangement becomes important during the transient: as tension is recovered, some half-sarcomeres lengthen while others shorten. This leads to a flat T2 curve, as observed experimentally. In addition, we investigate the isotonic transient response and show that for a range of parameter values the model displays damped oscillations, as recently observed in experiments on single muscle fibers. We conclude that it is essential to consider the collective dynamics of many sarcomeres, rather than the dynamics of a single pair of filaments, when interpreting the transient response of muscle.
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"abstract": "We investigate the isometric transient response of muscle using a\nquantitative stochastic model of the actomyosin cycle based on the swinging\nlever-arm hypothesis. We first consider a single pair of filaments, and show\nthat when values of parameters such as the lever-arm displacement and the\ncrossbridge elasticity are chosen to provide effective energy transduction, the\nT2 curve (the tension recovered immediately after a step displacement) displays\na region of negative slope. If filament compliance and the discrete nature of\nthe binding sites are taken into account, the negative slope is diminished, but\nnot eliminated. This implies that there is an instability in the dynamics of\nindividual half-sarcomeres. However, when the symmetric nature of whole\nsarcomeres is taken into account, filament rearrangement becomes important\nduring the transient: as tension is recovered, some half-sarcomeres lengthen\nwhile others shorten. This leads to a flat T2 curve, as observed\nexperimentally. In addition, we investigate the isotonic transient response and\nshow that for a range of parameter values the model displays damped\noscillations, as recently observed in experiments on single muscle fibers. We\nconclude that it is essential to consider the collective dynamics of many\nsarcomeres, rather than the dynamics of a single pair of filaments, when\ninterpreting the transient response of muscle.",
"arxiv_id": "physics/0303087",
"authors": [
"Andrej Vilfan",
"Thomas Duke"
],
"categories": [
"physics.bio-ph",
"q-bio"
],
"doi": "10.1016/S0006-3495(03)74522-6",
"journal_ref": "Biophys. J. 85, 818-827 (2003)",
"title": "Instabilities in the transient response of muscle",
"url": "https://arxiv.org/abs/physics/0303087"
},
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