In the heart, eNOS is expressed in both endothelial cells and cardiomyocytes (Tirziu and Simons, 2008), and eNOS gene deletion results in a decreased heart rate (Bannister et al., 2011), left ventricular hypertrophy (Bannister et al., 2011), and impaired left ventricular relaxations (Vignon-Zellweger et al., 2011). Here, NOS3 is linked to left ventricular hypertrophy.