Simulated contribution of the differences in I_to, SERCA, and cTn levels to the kinetics of Ca²⁺ transient and of ΔSL in RVCM. (A and B) Calculated Ca²⁺ transients (A), Ca²⁺ flux to the troponin fraction (B), and half sarcomere shortening (ΔSL_half) obtained from the computations based on the models by Pandit et al. (2001) and Negroni and Lascano (2008). The black lines correspond to the computational changes in the control LVCM (calculated LVCM). The results by increasing the conductance of I_to by 31% alone (g_to ⋅ 1.31, red line) and combined with decreased SERCA (40.0% of control, blue line) or with lowered cTn (67% of control, green line). The combined changes of all three parameters are displayed by the gray line. (C) Effect of applying all the three parameter changes (g_to ⋅ 1.31, I_SERCA ⋅ 0.44, and cTn ⋅ 0.64) on the Ca²⁺ transient (gray line). *, P < 0.05; **, P < 0.01.