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Multiscale modeling of twitch contractions in cardiac trabeculae

Mijailovich, Srboljub M., Prodanovic, Momcilo, Poggesi, Corrado, Geeves, Michael A., Regnier, Michael (2021) Multiscale modeling of twitch contractions in cardiac trabeculae. Journal of General Physiology, 153 (3). ISSN 0022-1295. (doi:10.1085/jgp.202012604) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:85863)

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Understanding the dynamics of a cardiac muscle twitch contraction is complex because it requires a detailed understanding of the kinetic processes of the Ca2+ transient, thin-filament activation, and the myosin–actin cross-bridge chemomechanical cycle. Each of these steps has been well defined individually, but understanding how all three of the processes operate in combination is a far more complex problem. Computational modeling has the potential to provide detailed insight into each of these processes, how the dynamics of each process affect the complexity of contractile behavior, and how perturbations such as mutations in sarcomere proteins affect the complex interactions of all of these processes. The mechanisms involved in relaxation of tension during a cardiac twitch have been particularly difficult to discern due to nonhomogeneous sarcomere lengthening during relaxation. Here we use the multiscale MUSICO platform to model rat trabecular twitches. Validation of computational models is dependent on being able to simulate different experimental datasets, but there has been a paucity of data that can provide all of the required parameters in a single experiment, such as simultaneous measurements of force, intracellular Ca2+ transients, and sarcomere length dynamics. In this study, we used data from different studies collected under similar experimental conditions to provide information for all the required parameters. Our simulations established that twitches either in an isometric sarcomere or in fixed-length, multiple-sarcomere trabeculae replicate the experimental observations if models incorporate a length–tension relationship for the nonlinear series elasticity of muscle preparations and a scheme for thick-filament regulation. The thick-filament regulation assumes an off state in which myosin heads are parked onto the thick-filament backbone and are unable to interact with actin, a state analogous to the super-relaxed state. Including these two mechanisms provided simulations that accurately predict twitch contractions over a range of different conditions.

Item Type: Article
DOI/Identification number: 10.1085/jgp.202012604
Divisions: Divisions > Division of Natural Sciences > School of Biosciences
Depositing User: Michael Geeves
Date Deposited: 04 Feb 2021 16:02 UTC
Last Modified: 05 Feb 2021 17:34 UTC
Resource URI: (The current URI for this page, for reference purposes)
Geeves, Michael A.:
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