Endothelin receptor

Physiological functions

• ET_A is a subtype for vasoconstriction 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.
• ET_B1 mediates vasodilation, 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
• ET_C has yet no clearly defined function.
• ET receptors are also found in the nervous system where they may mediate neurotransmission and vascular functions.

Brain and nerves

Widely distributed in the body, receptors for endothelin are present in blood vessels and cells of the brain, choroid plexus and peripheral nerves. When applied directly to the brain of rats in picomolar quantities as an experimental model of stroke, endothelin-1 caused severe metabolic stimulation and seizures with substantial decreases in blood flow to the same brain regions, both effects mediated by calcium channels.

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