Diuretic and Natriuretic Response to a Salt Load in Hypertensive and Pre-Hypertensive Subjects

Abstract

The diuretic and saluretic response to the intravenous infusion of a 5% salt solution (5 g of NaCl/m² of body surface area) was examined in a group of normotensive subjects, in patients with uncomplicated essential hypertension, in normotensive women after toxemia of pregnancy and in subjects with ‘labile’ hypertension, who were normotensive at the time of the study. It was found that the 2 latter groups reacted to the procedure in a very similar manner as the subjects with hypertension, i. e. with a diuretic as well as saluretic response of rapid onset, in contrast to the gradual and much lesser rise in water and salt excretion observed in the normal control subjects. The diuretic response in all 3 experimental groups was more pronounced than the saluretic response. The use of a salt loading test appears to be useful in epidemiological and prospective studies on hypertension.

Exaggerated Natriuresis in the Course of Poststreptococcal Glomerulonephritis

“…This response, EN, has been described in patients with essential hypertension [2.3, 10,12,13]; in patients considered to be predisposed to the development of essential hypertension, i.e., patients with 'labile' hypertension and normotensive women following toxemia of pregnancy [14]; and in normotensive subjects made hypertensive acutely by infusion of metaraminol [15]. It has not been described in patients with hypertension in the course of chronic renal disease [16].…”

Natriuretic Activity of a Substance Isolated from Human Urine During the Excretion of a Salt Load

“…Four normotensive and 6 hypertensive sub jects received a hypertonic salt load according to the procedure described pre viously from this laboratory [1]. Details concerning all the subjects (age, sex, level of blood pressure and renal function as expressed by a previous 24-hour creatinine clearance) are given in table I.…”

Lack of Exaggerated Phosphaturia in Essential Hypertension

“…It is well known that patients with essential hypertension react to a solute load by a prompt rise in sodium and water excretion, that is generally referred to as 'exaggerated natriuresis' [3][4][5]7]. HS were also found to have increased calcium excretion following saline administration [1].…”

“…The results Hypertension show a dichotomy between the enhanced fractional sodium excretion in the hypertensive subjects and the fractional phosphate excretion, which tended to be lower in this group than in normotensive subjects. These findings suggest an alteration of distal sodium reabsorption as the cause of the 'exaggerated' natriuresis of hypertensive subjects following saline infusion.Acute extracellular volume expansion (ECVE) has been shown to cause increased urinary phosphate excretion in both experimental animals and man [6,9,12,14], The mechanism of the phosphaturia following ECVE is still contraversial: in the dog, ECVE enhances phosphate excretion independently of changes in glomerular filtration rate (GFR) and parathyroid activity [8,9,14]; in rats, however, phosphate diuresis is almost abolished by parathyroid ectomy [6].It is well known that following ECVE with saline solutions, patients with essential hypertension react with an 'exaggerated' natriuresis as compared to similarly treated normotensive subjects [3][4][5]7]. In a recent study, hypertensive subjects were also shown to have an increased calcium excretion in response to saline loading [1],…”