Abstract :
Mathematical modelling of cardiac cell activity has developed in roughly ten-year cycles over the last 30 years, with each major phase of modelling being focused around particular experimental questions. The first phase (around 1962) was based on the dissection of the K-currents in heart cells into the inward rectifier and delayed current components. The second phase (1975) was based on identifying separate slow current mechanisms in the plateau and pacemaker ranges of potential and on the discovery of the calcium current in cardiac muscle. The most recent phase (starting with the 1985 DiFrancesco-Noble model) was based on the identification of the hyperpolarization-activated pacemaker current and on the electrogenicity of sodium-calcium exchange. Although each of these developments has depended on advances in experiment method, it is also true that each has also needed to theorize ahead of the experiment work. There is, therefore, a bi-directional interaction between theory and experiment. Sometimes experimental work leads, sometimes the theoretical work does so. A major use of such models in the case of cardiac cells is their incorporation into integrative studies of how large networks of cardiac cells interact to produce normal and abnormal rhythms. This work has received a major boost from the introduction of massively parallel computers that provide the required speed and capacity. Already, models of networks of sinus node and atrial cells have been constructed.
