1. Endothelins (ETs) and sarafotoxins (SRTXs) belong to a family of 21
-amino-acid peptides comprising at least eight isoforms. 2. ET exerts
multiple pharmacological effects through its receptors. 3. This review
summarizes the observations and findings pointing to the existence of
receptor subtypes and leading to their identification. 4. Two recepto
r subtypes have been cloned and stably expressed. 5. The existence of
at least two more is predicted by dissimilar ligand potencies in diffe
rent tissues, kinetics of receptor-ligand interactions, and cross-link
ing of receptors and radiolabeled ligands.