Endothelin Receptor Antibodies

In mammals, the endothelin (ET) family comprises three endogenous isoforms, ET-1, ET-2 and ET-3, and the receptors that mediate their effects have been classified as the endothelin ETA and ETB receptors. Endothelin is able to activate a number of signal transduction processes including phospholipase PLA2, PLC and PLD. ETA receptors expressed in CHO cells couple to Gq and Gs. ETB receptors couple to Gq and Gi. Endothelin receptors are widely expressed, consistent with the physiological role of endothelins as ubiquitous endothelium-derived vasoactive peptides, contributing to the maintenance of vascular tone. Receptors are also localised to non-vascular structures such as epithelial cells as well as occurring in the central nervous system (CNS). In human vessels, ETA receptors are mainly located on vascular smooth muscle cells, with ETB receptors being present on endothelial cells lining the vessel wall. ETB receptors may play a role in the release of endothelium-derived relaxing factors such as nitric oxide (NO) and prostanoids from endothelial cells. ETA receptors present on smooth muscle cells are mainly responsible for contraction. A selective ETA receptor agonist has not been discovered to date. Sarafotoxin S6c is a selective ETB receptor agonist. Antagonists that block both ETA and ETB receptors include the peptide TAK044 and the non-peptide compounds bosentan and SB209670.