1. To characterize the renin-angiotensin-aldosterone system in elderly hypertensive patients, an angiotensin II antagonist, [Sar1,Ile8]angiotensin II, was infused into individuals 60 years old and older with and without hypertension.
2. After infusion of [Sar1,Ile8]angiotensin II in all of the elderly patients and subjects an agonistic pressor response was observed that was greater than in middle-aged hypertensive patients.
3. Pre-infusion plasma renin activity and plasma aldosterone concentration in hypertensive and normotensive elderly groups were suppressed in comparison with those in middle-aged hypertensive subjects. The increased agonistic effects of [Sar1,Ile8]angiotensin II infusion on blood pressure in the elderly are presumably due to their hyporeninaemia.
4. The angiotensin-aldosterone system in elderly essential hypertensive patients is suppressed and is presumably not responsible for their elevated blood pressures.