The endothelin (ET) family of proteins, which includes ET-1 (endothelin-1), ET-2 (endothelin-2) and ET-3 (endothelin-3), are vasoactive peptides that are involved in various functions throughout the body. Endothelins can affect the central nervous system and neuronal excitability, and they elicit potent vasoconstrictor action. While ET-1 is a potent, 21-amino acid vasoconstrictor peptide, ET-2 has the most potent vasoconstrictor activity. ET-3 functions as a ligand for endothelin receptor ty