Clinical and Experimental Studies on Angiotensin II Receptors in Arterial Wall and Adrenal Cortex

The effects of 1-sarcosine, 8-isoleucine-angiotensin II (AIIA) on blood pressure (BP), plasma renin activity PRA) and plasma aldosterone concentration (PAC) were evaluated in 20 patients with hypertension or water and lectrolytes disorders. Also the effects of AIIA were tested in the patients receiving a constant administration of angiotensin II (AII). The biological activities of AII and AIIA were estimated by a radiolegend receptor assay using 3H-AII and AII receptor isolated from bovine adrenal cortex. AIIA rose both systolic and diastolic BP in patients with low-renin levels, but did not in normal-and high-renin groups. AIIA significantly increased PAC correlated with pre-infusion PRA (r= - 0.593, p<0.01). AIIA inhibited the biological activities ofAII on BP and PAC, but did not on PRA. The constant rates of association (Ka) and dissociation (Kd) of AII forAII receptor in bovine adrenal cortex were ; Ka 1.09×l0M-1, Kd 9.16×l0-11M, respectively. However, with addition of AIIA, the binding of AII to the adrenal receptor was apparently blocked. These findings demonstra e the identity of the binding site in the adrenal gland and vascular wall for AII and AIIA, and that AIIA might be of value to assess the angiotensin II-receptor interaction in hypertension.