Functional characterization of the ET-1/AngII receptor expressed in Cos1pMAM-ET-1/AngII cells. (A) ET-1 (0.1 µmol/L) and AngII (0.1 µmol/L) induced 45Ca2+ mobilization in intact CoslpMAM-ET-1/AngII cells. 45Ca2+ efflux was measured as the % 45Ca2+ retained at 10, 20, and 30 sec. (B) Stimulation of 45Ca2+ mobilization (measured as % 45Ca2+ efflux activity at 30 sec) in response to various peptide ligands (0.1 µmol/L): AngII, AngIII, AngI, ET-1, ET-2, ET-3, AVP, and Bradykinin (Bradyk). Inhibition of 45Ca2+ efflux activity by Sar1, Ala8-AngII was tested with the concurrent incubation of AngII (1 nmol/L) or ET-1 (1 nmol/L) and Sar1, Ala8-AngII at 100 nmol/L. (C) Concentration dependence of the ET-1-induced 45Ca2+ mobilization (measured as % 45Ca2+-efflux activity at 30 sec). (D) Concentration dependence of the AngII-induced 45Ca2+ mobilization (measured as % 45Ca2+ efflux activity at 30 sec). (E) Competition for I25I-ET-1 specific binding by ET-1 (■), ET-2 (○), ET-3 (△), and AngII (♦). (F) Competition for 125I-AngII-specific binding by AngII (■), Losartan (○), PD123319 (▲), and ET-1 (□). Each curve is representative of at least three independent experiments performed in quadruplicate. Bars represent the ranges of intraexperimental variation.