In vivo studies showed both epinephrine and norepinephrine could potentiate LPS-induced expression of TNF through 2 adrenergic receptors. However, the effect of catecholamine on TNF production in human monocytes in the hypoxic microenvironment has never been studied. Our preliminary data showed epinephrine had no effect on TNF expression in human monocyte cell line U937 under normoxic condition but could attenuate the TNF expression under hypoxic condition. Therefore, we hypothesize that catecholamines can modulate intermittent hypoxia induced TNF and further affect the developments of cardiovascular complications in OSA. In this project, we’ll use peripheral blood monocytes from healthy subjects and OSA patients as the target cells, which were serially treated with catecholamine  or b antagonists in both normoxic and hypoxic microenvironments, to achieve the following 3 objectives: