Endothelins are peptides with exceptional vasoconstrictor potency. They play an important role in intercellular communications.

Endothelin-1, a 21-amino acid peptide from vascular endothelial cells of different mammalian species, is one of the most potent vasoconstrictors. ET-1 exerts a wide variety of effects on both vascular and non-vascular (e.g. heart, lung, brain) tissues. Toxic peptides from a snake venom, the sarafotoxins, show structural and functional homology to ET-1. The role of ET-1 in clinical hypertension has been reviewed by Dhaun et al. and by Sreenivas and Oparil. ET-1 plays a central role in lung fibrosis.