Effect of calcium activated chloride current on characteristics of DAD

High intracellular calcium concentration causes a transient inward current (I_n) that can provoke delayed after-depolarizations (DAD). I_n is comprised of sodium-calcium exchange current (I _NaCa) and calcium-activated chloride current (I_ClCa). We have developed a mathematical model of I_ClCa that was included into the atrium AP model by Linblad, Murphey, Clark and Giles (1996) (LMCG model). I_ClCa appears as an important component (30-40%) of I_n. The plots of DAD amplitudes and DAD higher slope as a function of extracellular Ca²⁺ concentration show an interval between 5 mM/l to 6 mM/l in which I_ClCa blockade could bring the DAD amplitude to a subthreshold level for triggered action potentials. Our results suggest that, at a high intracellular Ca²⁺ concentration, that provokes DAD generating conditions, I_ClCa blockade could be potentially antiarrythmogenic