Endothelin-1 (ET-1) is a peptide that constricts pulmonary blood vessels and raise blood pressure. Two ET-1 receptor subtypes, ET
A and ET
B, mediate the effects of ET-1 in the vascular smooth muscle and endothelium. The actions of ET
A would be vasoconstriction and cell proliferation, while the actions of ET
B would be vasodilatation, antiproliferation, and ET-1 clearance. Ambrisentan is a highly selective ET
A receptor antagonist with >4000-fold higher selectivity over the ET
B receptor. Pulmonary arterial hypertension (PAH) would be derived from the action of ET
A receptor. Therefore, ambrisentan is used for the treatment of PAH. For your reference, [
H1568] is a key synthetic intermediate of ambrisentan. (The product is for research purpose only.)