Sulfur Dioxide Effects on Human Atrial Action Potential: In Silico Study

Exposure to air pollutants agents, like sulfur dioxide (SO₂), has significant effects on the cardiovascular system. Studies have shown that SO₂ blocks ICaL and increases the I_Na, I_K1 and I_to currents, which implies action potential duration (APD) decrease, favoring the initiation of atrial arrhythmias. This study aims to assess the effects of the SO₂ at different concentrations on human atrial action potential, using computational simulation. For this, based on experimental data, we developed concentration-dependent equations to simulate the SO₂ effects on the currents. They were incorporated in the Courtemanche model of human atrial cell and in a 2D model of atrial tissue. S1-S2 cross-field protocol was applied to initiate a rotor. SO₂ concentrations from 0 to 100 μM were implemented. Our results are in agreement with results from non-human in vitro and in vivo studies. The SO₂ causes APD shortening and loss of plateau phase in a fraction that increases as the concentration increases. In the 2D model, a rotor can be generated from 50 μM of SO₂ concentration, showing a pro-arrhythmic effect.