Figure 17.

Modulation of cardiac electrical activity by activation of Ca²⁺-activated Cl⁻ channels in heart. Changes in action potentials (top) and membrane currents (bottom) due to activation of Ca²⁺-activated Cl⁻ channels are depicted. Top panel: numbers illustrate conventional phases of a prototype ventricular action potential under control conditions (black) and after activation of I_Cl (red). Range of estimates for normal physiological values for E_Cl is indicated in blue. Bottom panel: Range of zero-current values corresponding to E_Cl is shown in grey. Activation of I_Cl,Ca during [Ca²⁺]i overload results in oscillatory transient inward current (I_TI) and induction of delayed afterdepolarization (DAD) (dotted red lines). [Adapted, with permission, from Duan (48)]. (Copyright Request: Duan D. J Physiol 587: 2163-2177, 2009.)