Spectrum of deranged sodium homeostasis in essential hypertension.

Abstract

SUMMARY Essential hypertension is thought to produce a uniform exaggerated natriuresis and diuresis. Because validation of this formulation in humans is incomplete, the natriuretic and diuretic responses to acute volume expansion were characterized by using water immersion to the neck. This method provides a volume stimulus identical to that induced by 2 L of saline without plasma compositional change. Twenty-seven subjects with essential hypertension were studied on three occasions in the seated posture while in balance on a 10 mEq Na, 100 mEq K diet: during the seated control study, during 4 hours of head-out immersion, and during saline infusion (2 L/2 hours). Four subjects had exaggerated urinary Na excretion in response to neck immersion (Group 3), and 16 had a normal response (Group 2) indistinguishable from that of 15 previously studied normal subjects. The remaining seven subjects (Group 1) had blunted or absent natriuretic responses compared with that in normal subjects (p < 0.005). Similar results were obtained with saline administration; cumulative Na excretion in Group 1 was markedly less than that in Group 2 and the normal subjects. The heterogeneity in Na excretion indicates that an exaggerated natriuresis is not a uniform concomitant of essential hypertension. The significant inverse correlation between basal plasma aldosterone level and peak urinary as well as cumulative Na excretion suggests that plasma aldosterone constitutes a determinant of the differing natriuretic responses. In contrast to findings with urinary Na excretion, the diuretic responses of Groups 1 and 2 were identical. The striking dissociation between renal Na and water handling underscores the specificity of the derangement in renal Na handling.

Reduced nephron endowment due to fetal uninephrectomy impairs renal sodium handling in male sheep

“…This was associated with an elevated arterial pressure (∼ 10-15 mmHg) in the uni-x animals. Dissociation between diuresis and natriuresis has been reported in humans following volume expansion induced by head-out water immersion and maybe associated with the degree of central hypervolaemia achieved necessary for vasopressin suppression [30]. This suggests that the remnant kidney has a poor capacity to tightly and rapidly regulate sodium and water balance.…”

Effect of chronic sodium loading on cardiovascular response in young blacks and whites.

“…33 " 35 More recent investigations have demonstrated a heterogeneity in sodium excretion rates after saline loads in hypertensive patients. 36 Rydstedt et al 37 studied sodium excretion rates after saline infusion in hypertensive individuals grouped by before sodiumloading renin levels. Those with normal renin hypertension had a blunted rate of sodium excretion after a saline load.…”

Central Hypervolemia Does Not Invariably Modulate Calcium Excretion in Essential Hypertension

“…Our data permit a better analysis of the nonspecific (volume-induced) changes in urinary calcium excretion of hy pertensive humans [4], Wl studies were performed in 41 essen tial hypertensive subjects; they consumed a controlled diet containing 180 mmol sodium/day and 25 mmol calcium/day. As pre viously described by Epstein et al [5], WIinduced central hypervolemia identified two distinct populations with a markedly differ ent natriuretic response. Twenty-nine pa tients exhibited a significant diuretic re sponse (p < 0.001) and either appropriate or exaggerated natriuresis (from 121 ± 11 to 330 ± 24 pmol/min.…”