Ephaptic conduction in a cardiac strand model with 3D electrodiffusion

doi:10.1073/pnas.0801089105

Ephaptic conduction in a cardiac strand model with 3D electrodiffusion

^†Department of Mathematics, University of British Columbia, Vancouver, BC, Canada V6T 1Z2;
^§Leon H. Charney Division of Cardiology, New York University School of Medicine, New York, NY 10016; and
^¶Courant Institute of Mathematical Sciences, New York University, New York, NY 10012

Contributed by Charles S. Peskin, February 6, 2008 (received for review July 29, 2007)

Abstract

We study cardiac action potential propagation under severe reduction in gap junction conductance. We use a mathematical model of cellular electrical activity that takes into account both three-dimensional geometry and ionic concentration effects. Certain anatomical and biophysical parameters are varied to see their impact on cardiac action potential conduction velocity. This study uncovers quantitative features of ephaptic propagation that differ from previous studies based on one-dimensional models. We also identify a mode of cardiac action potential propagation in which the ephaptic and gap-junction-mediated mechanisms alternate. Our study demonstrates the usefulness of this modeling approach for electrophysiological systems especially when detailed membrane geometry plays an important role.

Footnotes

^‡To whom correspondence may be addressed. E-mail: mori{at}math.ubc.ca or peskin{at}cims.nyu.edu
Author contributions: Y.M., G.I.F., and C.S.P. designed research; Y.M. performed research; Y.M., G.I.F., and C.S.P. analyzed data; and Y.M., G.I.F., and C.S.P. wrote the paper.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/cgi/content/full/0801089105/DCSupplemental.