QUANTITATIVE AUTORADIOGRAPHY REVEALS DIFFERENT ANGIOTENSIN-II RECEPTOR SUBTYPES IN SELECTED RAT-BRAIN NUCLEI

Heterogeneity of rat brain angiotensin II receptors was revealed by quantitative autoradiography after incubation with I-125-Sar1-angiotensin II and displacement with the angiotensin II antagonists CGP 42112 A and DuP-753 and by receptor sensitivity to dithiothreitol. Receptors in areas involved in cardiovascular and fluid control-the subfornical organ, nucleus of the solitary tract, paraventricular nucleus, and area postrema-are displaced by DuP-753 with an IC50 of 1 x 10(-7) M, are sensitive to 5 mM dithiothreitol, and thus are angiotensin II type-1. Receptors in the inferior olive are displaced by CGP 42112 A (IC50, 1 x 10(-9)) but not by DuP-753 in concentrations up to 10(-4) M, are insensitive to 5 mM dithiothreitol, and thus are angiotensin II type-2.