NOS3 and endothelial dysfunction: 6 Endothelial dysfunction is an early marker for atherosclerosis preceding angiographic or ultrasonic evidence of atherosclerotic plaque formation. 4 Shear stress increases the expression of endothelial nitric oxide synthase signaling. Asymmetric dimethylarginine (ADMA) inhibits nitric oxide production, and elevated levels of ADMA have been associated with endothelial dysfunction and atherosclerosis. 7