A model of the action potential and underlying membrane currents in
a rabbit atrial cell .
Lindblad, D. S., C. R. Murphey, J. W. Clark, W. R. Giles.
Department of Electrical and Computer Engineering, Rice University,
Houston, TX 77251-1892, Dept. of Physiology and Biophysics, Univ. of
Texas Medical Branch, Galveston, TX 77550, Departments of Medical
Physiology and Medicine, University of Calgary Medical School,
Calgary, Alberta, Canada T2N 4N1
APStracts 3:0119H, 1996.
We have developed a mathematical model of the rabbit atrial myocyte
and have used it in an examination of the ionic basis of the atrial
action potential. Available biophysical data has been incorporated
into the model to quantify the specific ultrastructural morphology,
intracellular ion buffering, and time- and voltage-dependent currents
and transport mechanisms of the rabbit atrial cell. When possible,
mathematical expressions describing ionic currents identified in
rabbit atrium are based on whole-cell voltage-clamp data from
enzymatically isolated rabbit atrial myocytes. This membrane model is
coupled to equations describing Na + , K + , and Ca 2+ homeostasis,
including the uptake and release of Ca 2+ by the sarcoplasmic
reticulum (SR) and Ca 2+ buffering. The resulting formulation can
accurately simulate both the whole-cell voltage-clamp data upon which
it is based, as well as provide fits to a family of rabbit atrial
cell action potentials obtained at 35 ? x C over a range of stimulus
rates (0.2-3.0 ? Hz). The model is utilized to provide a qualitative
prediction of the intracellular [Ca 2+ ] i -transient during the
action potential and to illustrate the interactions between membrane
currents which underlie repolarization in the rabbit atrial myocyte.
Received 28 September 1994; accepted in final form 22 January
1996.
APS Manuscript Number H875-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 27 March 96