Nitric oxide (NO) is an important substance produced continuously by all blood vessels. It is thought to maintain health, in part, by preventing and suppressing inflammatory responses. NO is normally generated at the endothelium by a group of important enzymes called nitric oxide synthases. However, in chronic inflammatory states such as those seen in cardiovascular disease (CVD), the endothelial isoform of the enzyme becomes dysfunctional and produces less NO, and the NO that is produced is scavenged by the products of oxidative stress.