Effect of calcium-activated chloride current blockade on the delayed after depolarizations. Simulation study

High intracellular calcium conditions cause a calcium-activated transient inward current (I_ti) that can provoke oscillations in membrane potential called delayed after depolarizations (DAD). The current I_ti comprises of the sodium-calcium exchange current (I_NaCa) and the calcium-activated chloride current (I_NaCa). Lindblad, Murphey, Clark and Giles (1996) developed a mathematical model (LMCG model) of the rabbit atrial AP. In this study, a modified AP LMCG model that includes I_Cl-Ca. is used to evaluate the contribution of I_Cl-Ca to develop DADs. Our results suggest that although I_Na-Ca is the main component of I_ti (65%), I_Cl-Ca may play a significant role in DAD generation. Even more, the I_Cl-Ca blockade could inhibit the DAD propagation and trigger activity associated to high [Ca²⁺]_i condition, in atrial tissue.