Endothelinreceptors

Endothelin receptors are a family of G protein-coupled receptors that bind to endothelin peptides. There are two main subtypes, ETA and ETB, which differ in their amino acid sequence and tissue distribution. ETA receptors are primarily located in vascular smooth muscle cells and mediate vasoconstriction. ETB receptors are found on both endothelial cells and vascular smooth muscle cells. On endothelial cells, ETB receptors are coupled to nitric oxide synthase and mediate vasodilation. On vascular smooth muscle cells, ETB receptors can also mediate vasoconstriction, depending on the signaling pathway activated.

Endothelin-1 (ET-1) is the most potent endogenous vasoconstrictor known. It is produced by endothelial cells and circulates in the blood. ET-1 binds to both ETA and ETB receptors, but with different affinities. ETA receptors have a higher affinity for ET-1. The endothelin system, involving endothelin peptides and their receptors, plays a significant role in regulating vascular tone, blood pressure, and cardiovascular homeostasis. Dysregulation of this system has been implicated in various cardiovascular diseases, including hypertension, pulmonary hypertension, and heart failure. Consequently, endothelin receptor antagonists have been developed as therapeutic agents for these conditions.