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/sub ti/) that can provoke oscillations in membrane potential called delayed after depolarizations (DAD). The current I/sub ti/ comprises of the sodium-calcium exchange current (I/sub NaCa/) and the calcium-activated chloride current (I/sub 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/sub Cl-Ca/. is used to evaluate the contribution of I/sub Cl-Ca/ to develop DADs. Our results suggest that although I/sub Na-Ca/ is the main component of I/sub ti/ (65%), I/sub Cl-Ca/ may play a significant role in DAD generation. Even more, the I/sub Cl-Ca/ blockade could inhibit the DAD propagation and trigger activity associated to high [Ca/sup 2+/]/sub i/ condition, in atrial tissue.