Effects of two angiotensin II analogues on blood pressure, plasma aldosterone concentration, plasma renin activity and creatinine clearance in normal subjects on different sodium intakes.

Two angiotensin II analogues (AIIA), 1-sarcosine, 8-isoleucine angiotensin II ([Sar, Ile]-AII) and 1-sarcosine, 8-alanine angiotensin II ([Sar, Ala]-AII), were infused in six normal volunteers on high, regular and low sodium diets. The agonist and antagonist activities of these AIIA on blood pressure (BP), plasma aldosterone concentration (PAC), creatinine clearance and plasma renin activity were examined. Both AIIA had agonistic pressor activities in subjects on high and regular sodium diets, [Sar, Ile]-AII being more potent than [Sar, Ala]-AII. Both AIIA caused similar elevation of PAC in subjects on high and regular sodium diets, and an equally fall in PAC in subjects on a low sodium diet. Both AIIA strongly antagonized the rise in BP, the increase in PAC and the reduction of Ccr induced by AII administration in subjects on all three sodium diets. The results indicate that both AIIA can be used to examine the activity of the renin-angiotensin system in patients with hypertension, and they also suggest that AII interaction with its receptors differs in different target tissues.