LabHEART An Interactive Model of Cardiac Cell:
Ca Regulation and Ionic Currents.

Jose L. Puglisi and Donald M. Bers
Department of Physiology, Loyola University Chicago, Maywood, IL 60153

Since the seminal work of Hodgkin & Huxley, quantitative description of biological systems has become a rapidly emerging field. The increasing power of new computers allows the elaboration of more sophisticated models but many of them lack flexibility. In order to alter some of the crucial parameters of a simulation, the user has to be familiar with the language used in the implementation. The Department of Physiology of Loyola University has developed a new model that incorporates the latest findings on cardiac calcium regulation and is user friendly as well. Using G-Language (National Instrument) we developed LabHEART. This model incorporates the major mechanisms involved in the generation of cardiac action potentials (AP) and calcium transients. Extremely versatile, LabHEART allows the user to modify parameters such as channel conductance, pump rates, amount of calcium buffers by a simple click on an icon. Stimulation protocol and ionic concentrations can be changed "on-line" by dragging on a control button. One can easily switch between Voltage-clamp and Current-clamp. Graphs such as I-V set, Steady-state inactivation or Recovery curves are also generated. In all cases the output can be printed or saved in an ASCII form for further analysis. The model runs readily on a PC machine and has proved to be useful for research and teaching. A free copy of this software can be obtained at