Angiotensin II receptor subtypes in the rat brain.

The non-peptide angiotensin II (AII) receptor subtype selective antagonist, DuP 753, was used to characterize AII receptor binding sites in the rat brain. DuP 753 competed for specific 125I-[Sar1,Ile8]AII (125I-SIAII) binding in many brain nuclei (IC50 = 20-30 nM), but was a weak competitor at remaining sites (IC50 greater than 10(-4) M). DuP 753 sensitive binding sites (designated AII alpha subtype) correspond with areas where binding is inhibited by sulfhydryl reducing agents, whereas DuP 753 insensitive sites (AII beta) correspond with areas where binding is not inhibited by sulfhydryl reducing agents.