Arginase upregulation and the resulting decreased bioavailability of NOS have been reported to contribute to the pathophysiology of disease processes in which NO signaling is dysregulated, such as aging (Berkowitz et al., 2003), hypertension (Demougeot et al., 2005), and endotoxemia (Khadour et al., 2002). Here, NOS1 is linked to hypertensive disorder.