Two angiotensin II binding sites in rat brain revealed using [125I]Sar1, Ile8-angiotensin II and selective nonpeptide antagonists.

[125I]Sar1, Ile8 angiotensin II labeled two distinct binding sites in rat brain. The displacement potencies of WL-19, a selective ligand for the angiotensin II subtype 2 receptor, angiotensin II and related peptides indicated that one binding site in the rat brain is the same as the adrenal angiotensin subtype 2 receptor. The second binding site in rat brain was displaced by the selective angiotensin II subtype 1 receptor antagonist DuP-753; however, the displacement potencies of angiotensin II, angiotensin III and Ile7-angiotensin III were significantly less than at the adrenal angiotensin subtype 1 receptor. The data suggests that this binding site in rat brain may represent an angiotensin II receptor subtype which shares some characteristics with the adrenal angiotensin subtype 1 receptor.