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Endogenous driving and synchronization in cardiac and uterine virtual tissues: bifurcations and local coupling

Benson, A.P., Clayton, R.H., Holden, A.V., Kharche, S. and Tong, W.C. (2006) Endogenous driving and synchronization in cardiac and uterine virtual tissues: bifurcations and local coupling. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 364 (1842). pp. 1313-1327. ISSN 1471-2962

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Abstract

Cardiac and uterine muscle cells and tissue can be either autorhythmic or excitable. These behaviours exchange stability at bifurcations produced by changes in parameters, which if spatially localized can produce an ectopic pacemaking focus. The effects of these parameters on cell dynamics have been identified and quantified using continuation algorithms and by numerical solutions of virtual cells. The ability of a compact pacemaker to drive the surrounding excitable tissues depends on both the size of the pacemaker and the strength of electrotonic coupling between cells within, between, and outside the pacemaking region.

We investigate an ectopic pacemaker surrounded by normal excitable tissue. Cell–cell coupling is simulated by the diffusion coefficient for voltage. For uniformly coupled tissues, the behaviour of the hybrid tissue can take one of the three forms: (i) the surrounding tissue electrotonically suppresses the pacemaker; (ii) depressed rate oscillatory activity in the pacemaker but no propagation; and (iii) pacemaker driving propagations into the excitable region.

However, real tissues are heterogeneous with spatial changes in cell–cell coupling. In the gravid uterus during early pregnancy, cells are weakly coupled, with the cell–cell coupling increasing during late pregnancy, allowing synchronous contractions during labour. These effects are investigated for a caricature uterine tissue by allowing both excitability and diffusion coefficient to vary stochastically with space, and for cardiac tissues by spatial gradients in the diffusion coefficient.

Item Type: Article
Copyright, Publisher and Additional Information: © 2006 The Royal Society
Keywords: pacemaking, ectopic focus, bifurcation, excitable medium
Institution: The University of Sheffield, The University of Leeds
Academic Units: The University of Leeds > Faculty of Medicine and Health (Leeds) > School of Medicine (Leeds) > Leeds Institute of Genetics, Health and Therapeutics (LIGHT) > Academic Unit of Cardiovascular Medicine (Leeds)
The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Computer Science (Sheffield)
The University of Leeds > Faculty of Biological Sciences (Leeds) > Institute of Membrane and Systems Biology (Leeds)
Depositing User: Repository Officer
Date Deposited: 19 Jun 2006
Last Modified: 05 Jun 2014 11:06
Published Version: http://www.journals.royalsoc.ac.uk/openurl.asp?gen...
Status: Published
Publisher: The Royal Society
Refereed: Yes
Identification Number: 10.1098/rsta.2006.1772
URI: http://eprints.whiterose.ac.uk/id/eprint/1310

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