Endothelial function is a research area that focuses on studying the health and functioning of endothelial cells, which line the interior surface of blood vessels and play a crucial role in regulating blood flow, maintaining vascular tone, and preventing blood clot formation. Impaired endothelial function is associated with various cardiovascular diseases, such as atherosclerosis, hypertension, and heart failure. Research in this area aims to understand the underlying mechanisms of endothelial dysfunction and develop interventions to improve endothelial health and function, ultimately reducing the risk of cardiovascular events. Various techniques, such as flow-mediated dilation and nitric oxide measurement, are used to assess endothelial function in research studies.