NCX1 tail currents under AP-clamp. (A) AP clamp recording in a rabbit ventricular myocytes from Weber et al. [54]. (B) Model prediction of NCX1 tail currents upon AP-clamp interruption at various times (10, 25, 50, 100, 200, and 300 ms) with original Greenstein and Winslow [47] model. (C) Model prediction of NCX1 tail currents with fcyto = 1.0 (100% NCX1 in cytosol). (D) Model prediction of whole-cell NCX1 tail currents with fd, fpd, and fcyto values of 0.15, 0.30, and 0.55, respectively (dyad-to-PD ratio of 1:2).