Pressor hormones in elderly hypertensive persons racial differences

Abstract

The purpose of this study was to examine pressor hormones and platelet α2-adrenergic receptors in elderly unmedicated free-living subjects. Eighty-seven subjects, 70±5 years old (mean±SD), hypertensive or nonnotensive (blood pressure < 160/90 mm Hg) were recruited for measurement of blood levels of norepinephrine, epinephrine, and vasopressin, as well as density and affinity of α2-adrenergic receptors from platelet membranes, assessed by maximal binding (Bmax) and dissociation constant (Kd) of rauwolscine. They were separated into white hypertensive (n=22) or normotensive (n=41), and black hypertensive (n=11) or nonnotensive (n=13) groups, with similar age distribution throughout and similar blood pressure levels in the hypertensive and normotensive groups. Vasopressin was higher in the black hypertensive than white hypertensive group (1.5±1.0 vs. 0.7±0.5 pg/ml, respectively, p < 0.005), whereas epinephrine correlated inversely with diastolic blood pressure (r= −0.7, p < 0.02, in the black hypertensive group). Kd was higher in the black normotensive group than in the other groups (1.6±0.6 vs. 1.0±0.2,1.1 ±0.3, or 1.0 ±0.3 nM in the white normotensive, black hypertensive, or white hypertensive group, respectively, p < 0.002). Bmax was no different among groups but was significantly correlated with vasopressin levels for the whole group (r=0.4, < 0.0004) although no such correlation existed within the black hypertensive group. The data suggest that various vasoconstrictor systems participate to different extents in the mechanisms generating and sustaining hypertension in elderly white and black subjects. © 1990 American Heart Association, Inc.