Isoforms and Organ Distribution
There are three isoforms (identified as ET-1, -2, -3) with varying regions of expression and two key receptor types, ETA and ETB (see EDN1, EDN2, EDN3).
- ETA 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.
- ETB is primarily located on the endothelial cells that line the interior of the blood vessels. When endothelin binds to ETB 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.
- Both types of ET receptor are found in the nervous system where they may mediate neurotransmission and vascular functions.
Read more about this topic: Endothelin
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