Endothelin Receptor

Endothelin receptors are G protein-coupled receptors whose activation results in elevation of intracellular-free calcium. There are at least four type known, ETA, ETB1, ETB2 and ETC. ETA is a subtype for vasoconstriction. These receptors are found in the smooth muscle tissue of blood vessels, and binding of endothelin to ETA increases vasoconstriction (contraction of the blood vessel walls) and the retention of sodium, leading to increased blood pressure. ETB1 mediates vasodilation, when endothelin binds to ETB1 receptors, this leads to the release of nitric oxide (also called endothelium-derived relaxing factor), natriuresis and diuresis (the production and elimination of urine) and mechanisms that lower blood pressure. ETB2 mediates vasoconstriction. ETC has yet no clearly defined function. ET receptors are also found in the nervous system where they may mediate neurotransmission and vascular functions.