Endothelins (ET-1, 2, and 3) are considered to be very powerful vasoconstrictive substances. In humans, endothelins mediate their actions via two specific G-Protein coupled receptors, ETAR and ETBR. Both ETAR and ETBR are present in the heart and in human myocardium at similar levels.nThe endothelin receptors differ in their ligand specificity. While ETAR has varying affinities for the endothelin isoforms (ET-1 >ET-2>ET-3), ETBR shows no selective affinity.Hypermethylation of the ETBR correlated with transcriptional down-regulation and reduced expression of ETB receptor was observed in several prostate, bladder and colon cancer cell lines
