Figure 5.

Simulated time courses of L-type Ca²⁺ current (I_CaL) and Na⁺/Ca²⁺ exchanger current (I_NCX) under action potential (AP)-clamp in heart failure (HF). Simulated I_CaL and I_NCX have been obtained with our updated rabbit ventricular myocyte model that integrates detailed descriptions of electrophysiology, Ca²⁺ and Na⁺ handling, PKA and CaMKII signaling, and myofilament contraction. A-B Simulated I_CaL and I_NCX under AP-clamp at 2 Hz pacing in control (left) and HF (right) with physiological Ca²⁺ handling. C-D Simulated I_CaL and I_NCX after nifedipine (Nife) treatment (simulated assuming complete block of I_CaL) under AP-clamp at 2 Hz pacing in control and HF. E-F Nifedipine-sensitive current (I_Nife) expressed as sum of the changes in simulated I_CaL and I_NCX before and after nifedipine treatment in control and HF.