An electronic circuit simulating T-type calcium-channel current from the sinoatrial node

A circuit that simulates T-type calcium-channel current characteristics of the sinoatrial (SA) node was developed from discrete electronic components and tested at physiologic membrane voltage ranges. The circuit design was based on the T-type calcium-channel current dynamics obtained from a mathematical model of the SA node membrane, which, in turn, is based on physiologic data. The design was held at a resting membrane potential and then stepped to new voltages over the entire operating range of the T-type calcium channel. The circuit was validated by comparing its transient response current with the predicted current from the mathematical model. In addition, the peak currents of the circuit were compared with plots of peak current obtained from the mathematical model and physiologic data. By showing that the electronic circuit mimics the T-type calcium-channel current dynamics found within the SA node, the results may provide a foundation for developing a novel cardiac pacemaker that is based on the ion-channel characteristics of excitable tissue.