AGING AND BLOOD-PRESSURE REGULATION - DOSE-RESPONSE RELATIONSHIPS FORANGIOTENSIN, BLOOD-PRESSURE, ATRIAL-NATRIURETIC-PEPTIDE AND ALDOSTERONE IN NORMAL SUBJECTS OF VARYING AGES

1. Infusion of increasing doses of angiotensin II (AII) in normal subj ects sequentially increased blood pressure, aldosterone and atrial nat riuretic peptide (ANP) levels. 2. The slope of ANP response to AII was positively correlated with basal ANP and with the slope of blood pres sure response to AII (pressor slope) but not with age. 3. This is cons istent with the response of ANP to AII being mediated partly by the ri se in blood pressure, independent of ageing. 4. As expected in a selec ted normotensive population, there was no correlation between basal bl ood pressure and age, but pressor slope was positively correlated with age. 5. Thus, dose-response relationships may be an index of age-indu ced alterations in pressure regulatory mechanisms.