Endothelin receptor

There are at least four known endothelin receptors, ET_A, ET_B1, ET_B2 and ET_C,^[1] all of which are G protein-coupled receptors whose activation result in elevation of intracellular-free calcium,^[2] which constricts the smooth muscles of the blood vessels, raising blood pressure, or relaxes the smooth muscles of the blood vessels, lowering blood pressure, among other functions.

Physiological functions

• ET_A is a subtype for vasoconstriction^[1] These receptors are found in the smooth muscle tissue of blood vessels, and binding of endothelin to ET_A increases vasoconstriction (contraction of the blood vessel walls) and the retention of sodium, leading to increased blood pressure.^[3]
• ET_B1 mediates vasodilation,^[1] When endothelin binds to ET_B1 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.
• ET_B2 mediates vasoconstriction^[1]
• ET_C has yet no clearly defined function.^[1]
• ET receptors are also found in the nervous system where they may mediate neurotransmission and vascular functions.^[4]

Brain and nerves

Widely distributed in the body,

A similar strong vasoconstrictor action of endothelin-1 was demonstrated in a peripheral neuropathy model in rats.^[6]

Clinical significance

Mutations in the EDNRB gene are associated with ABCD syndrome^[7] and some forms of Waardenburg syndrome.^[8]

See also

• Endothelin receptor antagonist

References