Two endothelin receptor subtypes in porcine arteries

Endothelin-1 (ET-1) and ET-3 caused constrictions of endothelium-denuded porcine coronary artery strips with different concentration-response curves: a typical sigmoidal curve to ET-1 and a two-phase sigmoidal curve to ET-3. Binding assays using a membrane preparation demonstrated different B max values for [ 125 I]ET-1 and [ 125 I]ET-3 binding. In addition, [ 125 I]ET-1 binding was inhibited by ET-1 and ET-3 with different potencies (ET-1>ET-3), while [ 125 I]ET-3 binding was inhibited by both ETs equally