Table 2.

Sum of squares error (divided by 100) between experimental action potential duration (APD) rate dependence mean data (from Figure 8 in O'Hara et al., 2011) and the original O'Hara Rudy model (original ORd) (O'Hara et al., 2011), the original IKr-dyn ORd (Li et al., 2017) as well as the optimized IKr-dyn ORd under different conditions: control, mexiletine (blocks mainly INaL), HMR 1556 (blocks IKs), E-4031 (blocks IKr), BaCl2 (blocks IK1) and nisoldipine (blocks ICaL).

Experiment	Sum of squares error
	Original ORd	Original IKr-dyn ORd	Optimized IKr-dyn ORd
Control	17.20	18.82	22.63
Mexiletine (INaL)	92.92*	91.09	18.36
HMR 1556 (IKs)	56.35	57.08	55.34
E4031 (IKr)	145.03	144.87	72.33
Bacl2 (IK1)	29.83	67.47	11.41
Nisoldipine (ICaL)	5.29	54.62	4.76
Average	57.77	72.33	30.81

^*Error was calculated using the updated mexiletine IC50 data (Crumb et al., 2016); using the block suggested in the ORd paper of 90% INaL block (O'Hara et al., 2011), the sum of squares error is of 38.48, changing the average error to 48.70.