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PubMedDate not supplied

[Salt-free diet and diuretics in the elderly (author's transl)].

A salt-free diet is usually useless or dangerous in the elderly subject. It has at present only rare indications, such as after acute pulmonary oedema or congestive heart failure during initial treatment. In all other cases, it may be replaced by a reasonable diet; sodium intake remains permitted, but naturally one should not fall in the opposite extreme. As in younger subjects, and provided one takes into consideration the subjacent renal condition, properly prescribed diuretics have transformed the situation in the treatment of heart failure as in essential hypertension. Naturally the patient still requires regular clinical supervision and laboratory tests which may in practice be limited to periodical estimation of blood urea and serum potassium, less regularly, blood sugar and uric acid.

Aged↗
PubMed1975

[Salt-free diets].

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Diet, Sodium-Restricted↗
PubMed1989

[Effects of sodium depletion in rats actively immunized against renin].

The influence of active immunization against renin on systolic blood pressure in response to a dietary sodium restriction was assessed in normotensive rats (WKY) and spontaneously hypertensive rats (SHR). Immunization was obtained by multiple injections of pure submaxillary murine renin. Animals received a normosalt diet (NS diet) for 6 days. Then sodium was abruptly removed from the diet (LS diet), and rats were maintained for an additional 6 day-period on this salt-free diet. In rats maintained on NS diet, immunization induced a decrease in systolic blood pressure (SBP) about 11 p. 100 and 27 p. 100 respectively in WKY immune and SHR immune groups. SBP was not affected by abrupt dietary sodium removal in non-immunized rats from both strains. However, in immunized rats sodium restriction was accompanied by a significant SBP decrease compared to the value observed during NS period in the same group. The relative variation in SBP was about 10 p. 100 and 14 p. 100 respectively in WKY immune and SHR immune groups. The present study shows that active immunization against renin leads to a reduction in systolic blood pressure regardless to the initial pressure level. When sodium is removed from the diet, systolic blood pressure level is maintained in non-immunized rats, whereas it decreases in immunized rats of both strains. These results confirm the importance of an efficient renin-angiotensin system in the adaptative response to sodium restriction.

Animals↗
PubMed1990

Effect of increased dietary calcium on the development of reduced renal mass saline hypertension in rats.

A diet fortified with calcium carbonate has been reported to reduce blood pressure in low-renin and salt-sensitive hypertensive patients. We have therefore examined the effect of increased dietary calcium on the development of reduced renal mass-saline hypertension in rats, a classical, low-renin, volume, and sodium-dependent model of hypertension. Rats with 70-75% reduction in renal mass were divided into experimental and control groups. The experimental rats were fed a sodium-free diet supplemented with calcium carbonate (2.0% calcium) and drank 1% saline for 5 weeks. Control rats consumed the salt-free diet and drank 1% saline for the same period. In control rats, as previously observed, blood pressure progressive increased from a control value of 120.0 +/- 1.2 to 174.2 +/- 1.2 mm Hg by the fifth week. In contrast, in the calcium-supplemented rats the development of hypertension was significantly attenuated; the blood pressure only increased from 117.0 +/- 1.2 to 134.0 +/- 3.8 mm Hg by the fifth week. This was associated with a 30% decrease in saline intake by the fifth week, with proportionate decreases in urine volume and sodium excretion but not potassium excretion. Urinary magnesium excretion increased. No such changes were seen in control rats. At the end of the treatment period, plasma levels of sodium, potassium, calcium, creatinine, BUN, and protein were not different, but plasma chloride and magnesium were lower in experimental rats; vascular smooth muscle cell membrane potentials were also not different. These data show that dietary calcium carbonate can attenuate the development of reduced renal mass-saline hypertension in the rat, possibly in part by altering sodium and water intake.

Animals↗
PubMed1975

The effect of angiotensin infusion, sodium loading and sodium restriction on the renal and cardiac adrenergic nerves.

The renal and cardiac adrenergic nerve patterns in rats infused with large and small amounts of angiotensin and in rats given NaCl plus DOCA, NaCl alone, and salt-free diets were examined by the histochemical fluorescence method. Infusion of small amounts of angiotensin led to a persistent blood pressure elevation whereas infusion of large amounts of angiotensin resulted in a transient rise in blood pressure, probably due to the development of tachyphylaxis. Nerve patterns were found to be normal in angiotensin-infused rats and in rats given NaCl. In rats given NaCl plus DOCA and in rats subjected to salt restriction, a partial or complete disappearance of the transmitter of the adrenergic nerve terminals were recorded. The findings suggest that angiotensin in itself is incapable of inducing visible alterations in the transmitter content of the terminals. The findings agree with the view that angiotensin potentiates a norepinephrine depletion of the terminals during sympathetic activity, since it can be assumed that increased plasma angiotensin levels as well as various degrees of increased sympathetic tonus were present in the rats subjected to salt restriction. The similar effect on the nerve terminals produced by the combined NaCl and DOCA administration is consistent with earlier reports of an increased turnover of norepinephrine in animals thus treated.

Angiotensin II↗
PubMed1977

Relationship between mineralocorticoids and renal Na+-K+-ATPase: sodium reabsorption.

To evaluate the mechanism responsible for the effect of deoxycorticosterone acetate (DOCA) on renal Na+-K+-ATPase, we compared the relative contribution of this hormone and of increased absolute sodium reabsorption (TNa) to the restoration of the enzyme in kidneys of adrenalectomized rats. In study A, adrenalectomized animals maintained on a salt-free diet received 5 mg/kg per day DOCA i.m., while sham-operated and untreated adrenalectomized rats receiving the same diet served as controls. Absolute TNa and Na+-K+-ATPase specific activity in the cortex and outer medulla of DOCA-treated rats were similar to those measured in untreated adrenalectomized animals, but were significantly lower than in sham-operated controls. In study B, the adrenalectomized rats did not receive DOCA but were fed a high salt diet and received isotonic saline, 50 ml/kg per day s.c. Absolute TNa and cortical and medullary Na+-K+-ATPase specific activity were significantly higher in the salt-loaded group than in both adrenalectomized and sham-operated rats deprived of salt. These results suggest that absolute sodium reabsorption is a major determinant of renal Na+-K+-ATPase activity, and that the effect of DOCA on this enzyme is secondary to its stimulation of absolute tubular sodium transport.

Adenosine Triphosphatases↗
PubMed1976

Dietary salt and round heart disease in turkey poults with a note on the minimum level of supplementary salt necessary in corn-soybean diets.

Round heart disease in turkey poults has been associated with high levels of dietary salt and when it occurs in the field recommendations often include a reduction in the level of dietary salt. Poults fed diets containing up to 1.5% salt and 1.5% sodium did not exhibit signs of round heart disease. A high mortality rate occurred with poults fed a salt-free diet. Post-mortem analysis generally revealed enlargement of the kidneys with urates; exudate was present in both abdominal and thoracic air sacs. Growth trials indicated that in order to maintain an optimum feed:body weight gain ratio, corn-soybean diets should contain at least 0.1--0.2% supplemental salt, and at least 0.2--0.3% salt when growth rate is considered. Minimum salt levels could not be reduced further by adjustment of the total dietary sodium:chloride ratio to unity.

Animal Feed↗
PubMed1975

Evidence against bicarbonate reabsorption in the ascending limb, particularly as disclosed by free-water clearance studies.

Bicarbonate reabsorption in the thick ascending limb of Henle's loop was examined by studies of free-water clearance (CH2O) and free-water reabsorption (TcH2O). During maximal water diuresis in the dog, CH2O/GFR was taken as an indes of sodium reabsorption in, and urine flow (V/GFR) as an index of delivery of filtrate to, this scarbonate, infusion of a nonreabsorbable solute (hypotonic mannitol) and administration of an inhibitor of bicarbonate reabsorption (acetaent, but less than that achieved with hypotonic saline infusion. This suggests that sodium that sodium bicarbonate is not reabsorbed in the ascending limb. Rather, it is the sodium chloride, swept out of the proximal tubule by osmotic diuresis due to nonreabsorbed mannitol or sodium bicarbonate, that is reabsorbed in the ascending limb thereby increasing CH2O, whereas the nonreabsorption of mannitol and sodium bicarbonate results in a depressed CH20 per unit V when compared with hypotonic saline. V/GFR is not a satisfactory index of delivery to the ascending limb during osmotic diuresis, since it includes water obligated by nonreabsorbable solutes. When a better index of delivery, the sum of the clearances of chloride (CC1) and free-water (CH2O) is used, hypotonic bicarbonate infusion, hypotonic mannitol infusion and acetazolamide administration increase CH2O/GFR per unit delivery to the same extent as odes hypotonic saline infusion. Studies in dogs and rats on TcH2O also indicate that sodium bicarbonate is an impermeant solute in the ascending limb. Osmotic diuresis due to sodium bicarbonate diuresis, produced either by inhibition of sodium bicarbonate reabsorption (acetazolamide, L-lysine mono-hydrochloride) or infusion of sodium bicarbonate, or mannitol diuresis both produced marked chloruresis and increased TcH2O to the same extent as did hypertonic saline infusion. If chloride excretion was almost eliminated by hemodialysis against a chloride-free dialysate (dogs) or prolonged feeding of a salt-free diet (rats), TcH2O formation was unimpaired if hypertonic saline was infused but virtually obliterated during mannitol or sodium bicarbonate diuresis. Sodium reabsorption in the ascending limb, therefore, appears to be dependent upon chloride as the accompanying anion. At any given rate of bicarbonate excretion, more cloride is delivered out of the proximal tubule (as estimated from CC1 + CH2O) with hypotonic sodium bicarbonate infusion than with acetazolamide administration. This suggests that magnitude of the chlorutesis accompanying bicarbonate diuresis depends, not only on osmotic diuresis due to nonreabsorbed sodium bicarbonate, but also on the extent to which concomitant changes in effective extracellular volume influence overall sodium chloride reabsorption.

Acetazolamide↗
PubMed1990

[Intestinal lymphangiectasis secondary to cicatricial fibrosis of mesenteric nodes: a nosologic entity?].

Exsudative enteropathy was suspected in a 27-year-old man with lower limb edema, hypoprotidemia and hypoalbuminemia. Gastrointestinal mucosa, kidney, liver, and heart were normal. Laparoscopy showed diffuse small intestine lymphangiectasia. This diagnosis was confirmed by the microscopic examination of several biopsies obtained at laparotomy. Pathological examination of peritoneal, lymph nodes, and liver biopsies showed fibrous thickening of the peritoneum and fibrosis of the lymph nodes. Our patient has been followed for 16 years. Substantial improvement of clinical symptoms was obtained by following a special salt-free diet containing short-chain triglycerides. However biochemical abnormalities have persisted. Exsudative enteropathy due to intestinal lymphangiectasia may be observed in heart and liver diseases as well as in malignant affections of mesenteric lymph nodes. If these conditions are excluded, intestinal lymphangiectasia may be considered as a primitive lymph vessel malformation. The discovery of primitive intestinal lymphangiectasia in an adult cannot be attributed to congenital abnormalities alone. Fibrosis encountered in some cases suggests that an inflammatory process of unknown origin may trigger the onset of intestinal lymphangiectasia.

Adult↗
PubMed1990

[Endocrine consequences of corticotherapy. Weaning from long-term corticotherapy].

Long term corticosteroid therapy has multiple effects on the endocrine system. These include adrenocortical suppression in high doses, alteration of gonadotropic and gonadal secretion, slowing down of long bone growth and bone maturation in children, osteoporosis in adults, alteration of the thyrotropic function and changes in thyroxine peripheral metabolism, diabetogenic effect. The list is not exhaustive, and there are more complex effects on the secretion of prolactin, pancreatic peptides, VIP, etc. Because of these various effects, the pros and cons of long term corticosteroid therapy must be carefully weighted, and if it is necessary steroids should be prescribed in such a way as to limit their side-effects: at best one dose taken in the morning every other day, together with the prescription of calcium, of a salt-free diet and, in some cases, of androgens or oestrogens. Weaning must be carried out with caution, to avoid rebound of the disease treated, and with substitution of hydrocortisone when the corticosteroid dosage reaches 5 mg per day of prednisone or equivalent and can be interrupted. The functional soundness or alteration of the corticotropic and adrenal functions must then be evaluated by testing corticotropic and adrenal functions must then be evaluated by testing the adrenocortical response to tetracosactrin, or even better by measuring early morning concentrations of blood cortisol. Depending on the results obtained, hydrocortisone can be withdrawn and limited to episodes of stress, or continued until ACTH and endogenous cortisol levels have returned to normal values.

Adrenal Cortex Hormones↗
PubMedDate not supplied

[State of the renin-angiotensin system in thyrotoxicosis].

A study was made of the blood plasma renin activity in 63 patients suffering from thyrotoxicosis before the treatment and in 42 healthy individuals. In comparison with the healthy, renin activity was increased in patients with thyrotoxicosis and displayed a positive correlation with the severity of the disease the level of protein-bound iodine, tachycardia and the degree of loss of weight. Stimulation of the renin-angiotensin system by the salt-free diet, hydrochlorthiazide and by placing the body into orthostatic position caused a relatively weaker increase in the renin activity in comparison with such in healthy individuals. Following successful treatment and the occurrence of an euthyroidal state renin activity proved to fall to the normal level. An increased renin activity was combined with increased urinary aldosterone excretion with a normal serum electrolyte level. Such combination pointed to the secondary character of aldosteronism. Block of the alpha- and beta-adrenergic receptors led to reduction in the level of renin activity. Despite the frequent affection of hepatic function there was revealed no correlation between the increase in the renin activity and the pathological results of hepatic tests. Plasma renin activity was reduced in 8 patients with myxedema. It is supposed that the principal factors causing activation of the renin-angiotensin system in thyrotoxicosis were the loss of water and electrolytes by the organism and the appearance of oversensitivity to adrenergic receptors.

Adrenergic alpha-Antagonists↗
PubMed1976

Interdependence of Na-excretion, plasma electrolytes, plasma volume and renal Na-K-ATPase-activity in hypertensive rats.

Hypertensive Goldblatt-rats have higher than normal Na-appetite and an enhanced Na-output. They have normal plasma Na- and K-concentration and kidney weight but a significantly reduced plasma volume. The amount of renal membrane protein and the renal Na-K-ATPase-activity of hypertensive rats was found to be significantly below that of controls. In order to evaluate the role of Na-appetite, Na-excretion rate and renal Na-K-ATPase-activity in the electrolyte balance, Goldblatt-rats with a stable hypertension and control animals were put for 8 days on a Na-free diet. Na-excretion rate of control rats reached a minimum (13 muEq/100 g x 24 hr) within 5 days and was maintained on this level up to the end of the experiment. Na-free diet did not alter either the kidney weight or the amount of membrane protein of the animals. However, in salt-free fed control rats total renal Na-K-ATPase-activity was found elevated by about 10% as compared to animals maintained on normal diet. Goldblatt-rats continuously excreted significantly higher amounts of Na (35 muEq/100 g x 24 hr), had sharply reduced plasma volume and plasma Na- concentration. The renal Na-K-ATPase-activity should no adaptation in gold blatt-rats. In all animals studied the rate of Na-excretion showed a close indirect correlation with the renal Na-K-ATPase-activity. It is concluded, that Goldblatt-rats depend on dietary Na to a higher extent than controls because of their reduced capacity to retain Na. The increased Na-appetite of hypertensive rats is a factor secondary to Na-loss.

Adenosine Triphosphatases↗
PubMed1990

A salt-hypertension hypothesis.

In urban Australia, the risk of retiring with hypertension is greater than 40%, and the basic abnormality--a rise in blood pressure (BP) with age--is almost universal. A hypothesis linking this with salt, therefore, concerns everyone. The diet of early humans was unsalted, and the Na content of breast milk (6 mmol/kg) shows how little NaCl is needed even during the most rapid period of growth. The hypothesis that the hypertonic concentration needed to preserve food causes the BP to rise with age is based partly on the normotensive status of contemporary "salt-free" societies and partly on experimental evidence. "Salt-free" populations seldom use alcohol and happen to be lean and active, with a low fat intake and largely vegetarian diet, but Westerners with similar virtues do not escape hypertension. Ideally, the prophylactic effect of avoiding salt would be ascertained in large-scale, prospective trials, but practical, ethical and, economic factors impose serious design problems. Nevertheless, a public health intervention based on this hypothesis would be incomplete without a serious attempt to measure the outcome.

Animals↗
PubMed1979

Stimulation of renin by acute selective chloride depletion in the rat.

To determine whether acute chloride depletion per se stimulates renin, we produced selective chloride depletion without sodium depletion in rats by peritoneal dialysis (PD) against 0.15 M NaHCO3 or 0.15 M NaNO3. Control rats were dialyzed against 0.15 M NaCl. Plasma renin activity (PRA) was measured before (PRA1) and 105 minutes after (PRA2) PD. Plasma volume was expanded after PD by infusion of salt-free albumin and was measured immediately after PRA2 by [131I]albumin. In experiment 1, rats were prepared on a normal diet. PRA2 (7.0 +/- 1.0 ng/ml per hr, mean +/- SEM) was increased (P less than 0.05) over PRA1 (4.7 +/- 0.7 ng/ml per hr) in Cl-depleted but not in control rats (PRA1 = 5.3 +/- 0.7, PRA2 = 6.1 +/- 0.7, P = NS). In experiment 2, to produce greater chloride depletion, all rats were prepared for 2 weeks on a low salt diet. PRA2 (47 +/- 5 ng/ml per hr) was increased as compared to PRA1 (24 +/- 2 ng/ml per hr, P less than 0.005) in the Cl-depleted group but not in the control group (PRA1 = 24 +/- 3, PRA2 = 27 +/- 6 ng/ml per hr, P = NS). Serum potassium and final plasma volume were slightly but not significantly lower than controls in these Cl-depleted rats. To exclude an additive effect of these two stimuli for renin, in experiment 2a we infused chloride-depleted rats with three times as much albumin as controls and with KHCO3, 100 mEq/liter. Despite volume expansion and potassium loading, PRA2 (41 +/- 6 ng/ml per hr) was significantly elevated as compared to PRA1 (25 +/- 4 ng/ml per hr, P less than 0.01). Since acute metabolic alkalosis also was present in all Cl-depleted renin-stimulated rats, an additional group (2b) was dialyzed against 0.15 M NaNO3; final plasma arterial pH (7.43) was not different from controls (7.42). Nevertheless, PRA2 levels again were higher (36 +/- 6 ng/ml per hr, P less than 0.05) as compared to PRA1 (23 +/- 4 ng/ml per hr). In all experiments, arterial blood pressure, glomerular filtration rate, and filtered sodium load were not different. Free water reabsorption was lower in Cl-depleted than in control rats. We conclude that acute selective chloride depletion per se is a potent stimulus for renin release.

Alkalosis↗
PubMed1992

Consumption of salty food by rats: regulation of sodium intake?

The extent to which sodium levels may be regulated by consumption was examined in two experiments that offered rats foods varying in sodium chloride (NaCl) content. In the first, rats received single purified diets containing from 0% to 3% NaCl. There were no effects of NaCl level on the amount or pattern of daily food intake; water intake, however, increased with salt content. In the second study, rats had choices between a NaCl-free food and a food containing either 1, 2, or 3% NaCl for 1 week each. Total food intake was unaffected. Proportional intake of the salt-free option increased with the salt content of the alternate food, but not sufficiently to maintain a constant NaCl intake. After 8 weeks of exposure to a single food, intake of the salty option increased in the choice tests, but the level of NaCl (from 0.5 to 3.0%) in the exposure-phase food did not affect the subsequent choice. We conclude that when only one food is available, salt intake is governed by caloric requirements and sodium levels are regulated by excretion. When foods differing in NaCl content are available, consumption does contribute to the regulation of sodium balance, but the amount consumed is not tightly controlled. Rats' salt preference appears to increase with age or with experience eating the purified foods offered here, but experience eating salty food does not affect the preferred level of salt.

Aging↗