<unk>  is a competitive antagonist of endothelin-1 at the endothelin-A (ET-A) and endothelin-B (ET-B) receptors. Under normal conditions, endothelin-1 binding of ET-A receptors causes constriction of the pulmonary blood vessels. Conversely, binding of endothelin-1 to ET-B receptors has been associated with<unk> th vasodilation and vasoconstriction of vascular smooth muscle, depending on the ET-B subtype (ET-B1 or ET-B2) and tissue.<unk>  blocks<unk> th ET-A and ET-B receptors, but is thought to exert a greater effect on ET-A receptors, causing a total decrease in pulmonary vascular resistance.
Bosentan
Macitentan
Ambrisentan
Sitaxentan
Darusentan
Vericiguat
Nitroxinil
Sildenafil