THE RESPONSE OF RENAL PLASMA-FLOW TO ANGIOTENSIN-II INFUSION IN A POPULATION-BASED SAMPLE AND ITS ASSOCIATION WITH THE PARENTAL HISTORY OF ESSENTIAL-HYPERTENSION

Background Results from previous studies suggested that a blunted resp onse of renal plasma flaw (RPF) to angiotensin II infusion during a hi gh-sodium diet (a phenotype associated with nonmodulation) is an inter mediate phenotype for essential hypertension, Objective To determine w hether RPF traits used to investigate nonmodulation have the character istics of intermediate traits when examined in a population-based samp le of adults aged 20-49.9 years, Design and methods We examined the fr equency distribution of baseline RPF and of its response to All infusi on using maximum-likelihood commingling analysis in order to investiga te the null hypothesis that the distributions of these traits are unim odal, We also examined the null hypothesis that there is no associatio n between these candidate intermediate traits and the parental history of essential hypertension. Results There was some evidence for the co mmingling of multiple distributions underlying these traits both for w omen and for men but the commingled distributions overlapped substanti ally and the inferences about the commingling of distributions were se nsitive to the method of RPF measurement, exclusion of outliers, and t he method of adjustment for concomitants. There was no statistically s ignificant association between any of the RPF traits and a parental hi story of essential hypertension. Conclusions There is not sufficiently strong evidence to advocate the use of this set of intermediate trait s to identify high-risk individuals or to relate genetic variation to the variation in risk of essential hypertension within this age range in the population at large.