Electrical interactions in the HL-1 cardiomyocyte culture: An experimental and computational study

A simplified computational model of mouse atrial cardiomyocyte electrical activity was developed, based on the HL-1 cardiomyocyte cell line. HL-1 myocytes were characterised electrically and optically: the emission spectra of di-4-ANEPPS in HL-1 cultures, the cell type and distribution, and the optical-electrical equiva- lence of the potentiometric probe were all examined. Two major cell types were determined: pacemaking and non-pacemaking, with a distribution of 70%/30% respectively. Optical mapping of the HL-1 monolayer revealed linear wavefronts and re-entrant rotor activity. Rotors were shown to be the dominant source of spontaneous activity in the HL-1 cultures.To reproduce experimentally observed electrical behaviour, a three-current generic ionic model was employed. Sharp electrode recordings of single cells were used to fit model parameters using a custom optimisation routine. An electrical cellular network model was created to replicate electrical interactions in the HL-1 mono- layer. The action potential waveshape and conduction velocity of the network model were optimised to accurately reproduce experimental data. The model was able to faithfully reproduce linear wave fronts and re-entrant rotor activity seen in the HL-1 monolayer. The radius-angle rotor relationship of the model was within one standard deviation of that observed in the HL-1 monolayer