Pathological Importance of the Endothelin-1/ETB Receptor System on Vascular Diseases
Figure 1
Roles of the ET-1/ET receptor system on vascular injury. (a) The vascular effects of ET-1 are mediated by ETA and ETB receptors. mediated ET-1 action has been considered to cause vascular injury. ETB receptors are expressed not only on vascular smooth muscle cells, but also on endothelial cells. In addition, the ETB receptor is a clearance receptor of ET-1 from the circulation. However, the roles of the ETB receptor on vascular injury are still controversial. Recently, it was reported that nonendothelial receptor induced vasoprotective effects, whereas another previous study demonstrated that receptor-mediated ET-1 action exhibited vasoprotective effects via NO production [25, 26]. (b) Inhibition of the ETB receptor system leads to an aggravation of vascular injury. Increased circulating ET-1 levels because of clearance receptor inhibition and the augmentation of mediated actions are mainly responsible for aggravated vascular injury in the ETB receptor-inhibited condition [9]. ET, endothelin; NO, nitric oxide; eNOS; endothelial nitric oxide synthesis; L-Arg. L-Arginine.
