An active vasodilator released by the vascular endothelium. It facilitates relaxation of vascular smooth muscle and inhibition of adhesion and aggregation of platelets. When the normal function of the endothelium is disrupted by mechanical trauma, hypertension, hypercholesterolemia, or atherosclerosis, less EDRF is released and the inhibition of platelet aggregation is decreased. In addition, the damaged vessels constrict. This favors the formation of thrombi.