Association of SMC CYB5R3 protein levels with RVmaxSP and biventricular cardiac remodeling in SS chimeras. CYB5R3 protein expression in pulmonary arterial SMC was determined for animals completing the 3- and 12-week studies. For the 3-week study, there was a trending association between SMC CYB5R3 protein expression and RVmaxSP: r = −.52, P = .069, n = 6-7 per group (A); corrected right ventricle mass (RV/Tibia): r = −.40, P = .10 (B); and corrected left ventricle + septum mass (LV+S/Tibia): r = −.43, P = .08; n = 8 per group for all (C). For the 12-week study, there was no obvious association of SMC CYB5R3 protein expression with RVmaxSP: r = .27, P = .46 (D); RV/Tibia: r = −.56, P = .09 (E); and LV+S/Tibia: r = −.17, P=.65; n = 5 per group for all (F). Correlation analyses were performed using Pearson r with significance set at <0.05.