Modeling spiral ca 2+ waves in single cardiac cells: role of the
spatial heterogeneity created by the nucleus.
Dupont, Genevieve, Jose Pontes, and Albert Goldbeter.
Unite de Chronobiologie Theorique, Faculte des Sciences, Universite
Libre de Bruxelles CP 231, Boulevard du Triomphe, B-1050 Brussels,
Belgium, Phone: 32-2-650 57 87. Fax: 32-2-650 57 87. E-mail:
gdupont@ulb.ac.be
APStracts 3:0144C, 1996.
Excitation-contraction coupling in cardiomyocytes is known to rely on
the Ca2+-induced Ca2+ release mechanism. This auto-amplification
process is also well apparent when voltage-clamped or Ca2+ overloaded
myocytes exhibit fast propagating Ca2+ waves. Although most of the
fronts are planar, some of them adopt a spiral shape, revealing some
additional characteristics about the excitability and structure of
the cardiac cell (Lipp and Niggli, 1993; Engel et al., 1994). Using a
previously developed model for Ca2+ oscillations and waves (Goldbeter
et al., 1990; Dupont and Goldbeter, 1994), we study by numerical
simulations different conditions in which spiral Ca2+ waves can occur
as a result of the spatial heterogeneity created by the nucleus, in a
system whose geometry resembles that of a myocyte. A region of the
cell lacking Ca2+ pools, acting as an obstacle able to break the
propagation of planar waves, suffices to initiate a spiral; however,
this region has to be properly placed with respect to the pacemaker.
An obstacle behaving as a barrier to diffusion is also able to create
the initial bending that can lead to the spiral. We study how the
occurrence of spiral Ca2+ waves in single cardiomyocytes is
influenced by factors such as the stimulus location and the position,
shape and dimensions of the obstacle to planar wave propagation.
Received 23 January 1996; accepted in final form 18 April 1996.
APS Manuscript Number C43-6.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 May 96