Obstructive sleep apnea (OSA) is associated with endothelial dysfunction and the development of cardiovascular disease. It is unclear how OSA results in endothelial dysfunction, but given the association between OSA and obesity, adipose-derived hormones (adipokines) are likely to be involved. Leptin, an adipokine upregulated in patients with OSA, has been shown to be associated with deleterious effects on vascular function resulting in impaired endothelial function. This proposal is directed at investigating the molecular mechanisms of endothelial dysfunction in OSA patients. We hypothesize that endothelial dysfunction associated with OSA is a result of molecular alterations within endothelial cells. As a part of these studies we will look at NO signaling pathways in adipose tissue and microvessels from normal and OSA subjects.