readme.txt

These PSpice files are for the paper:

Nicholas Sperelakis*1, Bijoy Kalloor2 and Lakshminarayanan Ramasamy2
Boundary effects influence velocity of transverse propagation of 
simulated cardiac action potentials
Address: 
1 Dept. of Molecular & Cellular Physiology
University of Cincinnati College of Medicine
Cincinnati, OH 45267-0576, USA and 
2 Dept. of Electrical Computer Engineering and Computer Science
University of Cincinnati, College of Engineering
Cincinnati, OH 45221, USA
Email: Nicholas Sperelakis* - spereln@ucmail.uc.edu; Bijoy Kalloor - kalloobs@email.uc.edu;
Lakshminarayanan Ramasamy - lramasamy@gmail.com
* Corresponding author

Published: 06 September 2005

Theoretical Biology and Medical Modelling 2005, 2:36 doi:10.1186/1742-4682-2-36
This article is available from: http://www.tbiomed.com/content/2/1/36

Abstract
Background: We previously demonstrated that transverse propagation of excitation
(cardiac action potentials simulated with PSpice) could occur in the absence of
low-resistance connections (gap - junction channels) between parallel chains of
myocardial cells. The transverse transmission of excitation between the chains
was strongly dependent on the longitudinal resistance of the interstitial fluid
space between the chains: the higher this resistance, the closer the packing of
the parallel chains within the bundle. The earlier experiments were carried out
with 2-dimensional sheets of cells: 2 × 3, 3 × 4, and 5 × 5 models (where the
first number is the number of parallel chains and the second is the number of
cells in each chain). The purpose of the present study was to enlarge the model
size to 7 × 7, thus enabling the transverse velocities to be compared in models
of different sizes (where all circuit parameters are identical in all models).
This procedure should enable the significance of the role of edge (boundary)
effects in transverse propagation to be determined.
Results: It was found that transverse velocity increased with increase in model 
size. This held true whether stimulation was applied to the entire first chain
of cells or only to the first cell of the first chain. It also held true for
retrograde propagation (stimulation of the last chain). The transverse
resistance at the two ends of the bundle had almost no effect on transverse
velocity until it was increased to very high values (e.g., 100 or 1,000 megohms).
Conclusion: Because the larger the model size, the smaller the relative edge area,
we conclude that the edge effects slow the transverse velocity.