FIGURE 5.

EAD generations during β-AS in the normal and LQT1 versions of the mTP06b model. (A) Simulated APs of the model cells under the basal condition (top) and conditions of β-AS as indicated by the points and arrows in (B). Model cells were paced at 1 Hz for 30 min. The dots denote EADs induced by spontaneous SR Ca²⁺ releases. (B) A phase diagram on the g_Ks–g_CaL parameter plane depicting displacements of critical points at which EADs emerged during 1-Hz pacing. The critical points were determined during g_CaL increases at an interval of 0.002 for individual g_Ks values increased at intervals of 0.02–0.1. For simulating the conditions of β-AS, the parameters other than g_CaL and g_Ks were modified as stated in the section “Materials and Methods” (see Supplementary Table S2). The LQT1 model cell was assumed to have reduced g_Ks of 50% or 25% of the control value. The points of the control (basal) conditions for cardiomyocytes with the normal and reduced g_Ks are labeled as “N” and “LQT1”, respectively. The arrows indicate the parameter shifts from the basal condition to the conditions of β-AS with g_Ks doubled and g_CaL increased to 140, 150, 160 and 180% of the control value.