AJP - Heart and Circulatory Physiology, Vol 243, Issue 2 207-H218, Copyright © 1982 by American Physiological Society
A mathematical model of primary pacemaking cell in SA node of the heart
D. G. Bristow and J. W. Clark
Application of voltage-clamp techniques to cardiac primary pacemaker tissue
is currently a subject of considerable interest in cardiac
electrophysiology. Information regarding the electrical behavior of this
type of membrane is by no means complete, yet sufficiently detailed
information is available in the literature that would allow the formulation
of a reasonably quantitative model to represent the electrical activity of
primary pacemaker tissue. In this study the well-known
McAllister-Noble-Tsien (MNT) model of the cardiac Purkinje fiber is
modified to account for the electrical activity of the primary pacemaking
cell (P-cell) of the sinoatrial (SA) node in the heart. Modification is
accomplished by appropriately deleting (or inactivating) selected inward-
or outward-current channels in the MNT model and adjusting the range of
voltage dependence of the various channel-gating variables. Wherever
possible, this is accomplished by taking into account voltage-clamp and
other electrophysiological data from experiments on the SA node. The
resultant model mimics published data quite well and is capable of
characterizing the free-running behavior of the primary pacemaker as well
as its response to injected currents.
