Dose-response curves for angiotensin II and synthetic analogues in three types of smooth muscle: existence of different forms of receptor sites for angiotensin II.

1 The dose-response curves for angiotensin II and four analogues in rat colon and uterus, and in rabbit aorta, were obtained.2 The ED(50) values of angiotensin II as well as the ED(50)s and intrinsic activities of angiotensin analogues varied between the three organs.3 The interaction of two competitive antagonists with angiotensin II receptors was also examined. The K(I) values obtained with both antagonists on the uterus differed from the values on the other tissues.4 It is concluded that angiotensin II receptors may be different in the three organs examined.