Correction of cardiovascular hypersensitivity to norepinephrine by potassium supplementation in normotensive members of hypertensive families and patients with essential hypertension

Abstract

Blood pressure (BP), plasma levels of norepinephrine (NE) and epinephrine, the chronotropic effect of isoproterenol, and the relationship between variations in BP and concomitant plasma NE levels obtained during NE infusion were studied under control conditions and after 10 days of dietary potassium supplementation (100 mmol/day) in 12 normotensive subjects with negative family history (FH) of hypertension (mean BP 111/70 +/- 9/7 mmHg), 11 normotensive subjects with positive FH (112/73 +/- 8/6 mmHg), and 10 subjects with untreated borderline to mild essential hypertension (131/89 +/- 15/9 mmHg). Under control conditions, the increase in circulating NE required to elevate mean BP by 20 mmHg was significantly lower in hypertensive subjects (6.1 +/- 4.0 nmol/l) or normotensive subjects with positive FH (5.0 +/- 2.4 nmol/l) than in normal subjects with negative FH (9.9 +/- 6.4 nmol/l); the other study parameters were similar. After potassium supplementation, plasma and urinary potassium increased and body weight decreased slightly in all groups; basal plasma NE and epinephrine levels and cardiovascular effects of isoproterenol were unchanged. However, in normotensive subjects with positive FH and hypertensive subjects, the increase in plasma NE required to elevate mean BP by 20 mmHg was normalized (to 8.9 +/- 5.9 and 9.9 +/- 6.9 nmol/l, respectively), while BP tended to decrease slightly. These findings indicate that dietary potassium supplementation may favorably modify noradrenergic BP-regulation in hypertension prone individuals.