miR-21-5p effects on immature human cardiomyocyte L-type calcium channel (LTCC) and SERCA2a (sarcoendoplasmic reticulum calcium-ATPase) activity were experimentally calibrated. A, Scatter plots of the initial population (grey dots) filtered (white dots) to be within 1 SD (boxed region) of calcium transient decay time constant (τCa), and calcium transient amplitude ([Ca2+]i amplitude) metrics from Figure 5. B, Accepted sets of calibrated model parameters. C and D, Histograms illustrating distributions of the output simulation metrics—(C) [Ca2+]i amplitude and (D) τCa—resulting from the accepted population of calibrated models. E, Ten select accepted model parameters were subsequently input into ischemic adult human cardiomyocyte models to predict miR-21-5p effects on calcium transients (grey) in comparison to healthy (black line) and ischemic (dotted black line) adult human cardiomyocytes. ΔGLCa and ΔVmaxup denote fold changes in LTCC and SERCA2a maximal flux constants, respectively, because of miR-21-5p effects.