Endothelial NOS, or eNOS, is an enzyme found in the endothelial cells that line blood vessels. It plays a crucial role in producing nitric oxide, a signaling molecule that helps regulate blood flow and maintain vascular health. By promoting the relaxation of blood vessels, eNOS contributes to lower blood pressure and improved circulation. The activity of eNOS is influenced by various factors, including shear stress from blood flow and the presence of certain hormones. Dysfunction of eNOS can lead to cardiovascular diseases, as it may result in impaired blood vessel function and increased risk of conditions like atherosclerosis.