A novel computational model of the human sinoatrial action potential

The sinoatrial node (SAN) tissue is responsible for the heart rhythm in physiological conditions. SAN cells are self-oscillating and the phenomena underlying this feature are well-described through electrophysiological experiments carried out on animals. Recently, human SAN cell data were recorded, but a human SAN action potential (AP) mathematical model is still lacking. Aim of this work is the formulation of a human SAN AP model that is able to reproduce the available experimental data. We started from the Severi-DiFrancesco SAN model (rabbit) and modified ion currents and calcium handling on the basis of available experimental data. The AP waveform and calcium transient generated by the model were compared to experimental traces. We also studied the effect of If ('funny current') block on cycle length. The model generates action potentials and calcium transients in line with experimental data. It can provide new insights into the phenomena that lead to the generation of SAN AP and allows us to study the effects of drugs that modulate the pacemaker activity.