Figure 7.

Overview of the major physiological functions of the arterial endothelium. (A) The endothelium forms a selective barrier regulating the solute flux and fluid permeability between the blood and surrounding tissues (105). (B) The formation of a thrombus or blood clot is referred to as coagulation and the breakdown of a thrombus is referred to as fibrinolysis. Normal endothelium has anti-thrombotic and pro-fibrinolysis properties, and actively represses platelet adhesion and aggregation. Vessel damage or exposure to pro-inflammatory molecules will shift the balance towards more pro-thrombotic/anti-fibrinolysis actions (106,107). (C) To regulate vascular tone, the endothelium releases various vasodilatory factors such as NO and EDHF, or vasoconstrictive factors such as ET-1 which will modify VSMC function (108). (D) In the case of inflammation, endothelial permeability will be increased. Endothelial cells will also recruit immune cells via the expression of adhesion molecules, and mediate their transmigration towards the inner vascular wall (107). The figure is based on a previous study (103). ECs, endothelial cells; VSMCs, vascular smooth muscle cells; NO, nitric oxide; EDHF, endothelium-derived hyperpolarizing factor; ET-1, endothelin-1.