Three apparent receptor subtypes for the endothelin/sarafotoxin family

Competition binding experiments performed with 125I-sarafotoxin (SRTX)-b and SRTX-b, SRTX-c and endothelin (ET-1 and ET-3) using homogenates of rat right and left atria, aorta, uterus, cerebellum and caudate putamen indicated heterogeneity of the ET/SRTX receptor. The evidence pointed to the existence of three receptor subtypes: a high-affinity ET-1/SRTX-b subtype typical of smooth muscle (E-S α receptor), a high-affinity SRTX-c subtype typical of the cerebellum (E-S β receptor), and a less selective subtype typical of the caudate putamen that binds all of these peptides with high affinity (E-S γ receptor).