Previous studies using the same KO strategy did not show definite differences in EF and FS between Npr1 global KO mice and WT mice, although indices of myocardial hypertrophy, such as end-diastolic interventricular septum, posterior wall, heart weight-to-body weight ratio (HW/BW), left ventricular weight-to-body weight ratio (LVW/BW), and right ventricular weight-to-body weight ratio (RVW/BW) were upregulated (Kilic et al., 2005). Here, NPR1 is linked to cardiac hypertrophy.