Sodium susceptibility and potassium effects in young patients with borderline hypertension.

Abstract

To evaluate sodium susceptibility in subjects with borderline hypertension at increased risk of developing essential hypertension, the effect of salt loading after sodium deprivation with a diuretic was studied in 21 young patients with borderline hypertension and 12 age-matched normal subjects. Treatment with a diuretic caused significant decreases in mean blood pressure (MBP) in subjects with borderline hypertension but not in normotensive subjects. In borderline hypertensives, the subsequent sodium loads resulted in a significant rise in MBP (5.8 ± 1.7%; p < .01), but sodium did not change MBP in normotensives. There is a good correlation between the increments in MBP with sodium loads and the decrements in MBP with a diuretic for each patient (r = -.759, p < .001). After diuretics, cardiac index (CI) as measured echocardiographically fell significantly but calculated total peripheral resistance (TPR) remained unchanged in subjects with borderline hypertension. After 180 meq sodium chloride each day was added for 7 days, CI (9.1 ± 2. 1 %; p < .01 ) and stroke index (21.0 + 3.4%; p < .01) rose significantly but TPR remained unchanged. Overall, the increments of MBP with sodium loads did not correlate with the changes in CI but did correlate with the changes in TPR (r = .567, p < .01). In these young patients with borderline hypertension, plasma norepinephrine and epinephrine concentrations and plasma renin activity (PRA) were significantly higher than in normotensive subjects. These results suggest that young patients with borderline hypertension differ from normal subjects in that they display a blood pressure increase due to a disproportionate rise in CI and inadequate fall in TPR in response to a short-term increase in dietary sodium and that adrenosympathetic overactivity and increased activity of the renin-angiotensin system may be partly involved. Moreover, during salt loading the 11 patients with borderline hypertension who received a dietary supplementation of 96 meq potassium chloride each day had less of an increase in MBP ( -1.6 2. 1% vs 5.8 + 1.7%; p < .05) andCl (-1.8 ± 2.0% vs9.1 ± 2.1%;p <.05) thandidthe21 patientswhohadnot taken the potassium supplement. PRA and plasma aldosterone concentration during salt loading were relatively higher in the potassium-supplemented patients as compared with in the ones that did not receive supplements. It is suggested that potassium supplementation may prevent the blood pressure rise with the sodium loading by attenuating the increase in cardiac output possibly as a result of the natriuresis. Circulation 69, No. 3, 468-476, 1984. YOUNG PATIENTS with borderline hypertension are at least three times more likely to develop established essential hypertension than are age-matched normotensive subjects.'l 2 Thus, young patients with borderline hypertension have been of particular interest to investigators because they may provide insight into the pathogenesis of essential hypertension. Borderline hypertensive subjects have been reported to have abnormali...

Sodium sensitivity in human subjects. Hemodynamic and hormonal correlates.

“…In contrast, Gudmundsson et al 38 found no significant changes in blood pressure, forearm blood flow, or resistance among normotensive men with and without a family history of hypertension subjected to a high sodium intake, and no differences in the degree of suppression of plasma renin activity or aldosterone concentration in those genetically predisposed to become hypertensive. Fujita et al 39 observed that patients with essential hypertension had greater changes in blood pressure than did normal subjects after receiving diuretics or sodium supplements; however, plasma norepinephrine, epinephrine, and renin activity were significantly higher than those of normotensive subjects. The increase in blood pressure was due to an increase in cardiac output with an inadequate fall in total peripheral resistance.…”

Protective Effect of Potassium Against the Hypertensive Cardiac Dysfunction

“…18,19 Therefore, it is a plausible hypothesis that potassium supplementation could attenuate salt retention during the high-salt diet period in DS rats, possibly through the natriuretic effect of potassium. [35][36][37] …”

Salt sensitivity. Definition, conception, methodology, and long-term issues.

“…51 Similarly, there are data to suggest that a high potassium diet ameliorates the hypertensive response to sodium administration in salt-sensitive subjects. 42 The many published studies also indicate that we still do not know the time period during which an individual has to consume a high salt diet before sodium sensitivity is apparent. If individuals followed one of the reported protocols for 1 month, 6 months, or 1 year, would more salt sensitivity be evident?…”