ArticleThe Journal of general physiology2020
Enhancing diastolic function by strain-dependent detachment of cardiac myosin crossbridges.
Article in The Journal of general physiology, 2020. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 5 papers.
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Who cites it
5 citing papers in PubMed.
- Strain rate of stretch affects crossbridge detachment during relaxation of intact cardiac trabeculae.PloS one · 2024Article
- Functional and structural differences between skinned and intact muscle preparations.The Journal of general physiology · 2022Review
- Inorganic phosphate accelerates cardiac myofilament relaxation in response to lengthening.Frontiers in physiology · 2022Article
- Reduced preload increases Mechanical Control (strain-rate dependence) of Relaxation by modifying myosin kinetics.Archives of biochemistry and biophysics · 2021Article
- Move quickly to detach: Strain rate-dependent myosin detachment and cardiac relaxation.The Journal of general physiology · 2020Article
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6 authors.
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Abstract
The force response of cardiac muscle undergoing a quick stretch is conventionally interpreted to represent stretching of attached myosin crossbridges (phase 1) and detachment of these stretched crossbridges at an exponential rate (phase 2), followed by crossbridges reattaching in increased numbers due to an enhanced activation of the thin filament (phases 3 and 4). We propose that, at least in mammalian cardiac muscle, phase 2 instead represents an enhanced detachment rate of myosin crossbridges due to stretch, phase 3 represents the reattachment of those same crossbridges, and phase 4 is a passive-like viscoelastic response with power-law relaxation. To test this idea, we developed a two-state model of crossbridge attachment and detachment. Unitary force was assigned when a crossbridge was attached, and an elastic force was generated when an attached crossbridge was displaced. Attachment rate, f(x), was spatially distributed with a total magnitude f0. Detachment rate was modeled as g(x) = g0+ g1x, where g0 is a constant and g1 indicates sensitivity to displacement. The analytical solution suggested that the exponential decay rate of phase 2 represents (f0 + g0) and the exponential rise rate of phase 3 represents g0. The depth of the nadir between phases 2 and 3 is proportional to g1. We prepared skinned mouse myocardium and applied a 1% stretch under varying concentrations of inorganic phosphate (Pi). The resulting force responses fitted the analytical solution well. The interpretations of phases 2 and 3 were consistent with lower f0 and higher g0 with increasing Pi. This novel scheme of interpreting the force response to a quick stretch does not require enhanced thin-filament activation and suggests that the myosin detachment rate is sensitive to stretch. Furthermore, the enhanced detachment rate is likely not due to the typical detachment mechanism following MgATP binding, but rather before MgADP release, and may involve reversal of the myosin power stroke.
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