Sodium Handling and Interaction in Numerous Organs

Abstract Salt (NaCl) is a prerequisite for life. Excessive intake of salt, however, is said to increase disease risk, including hypertension, arteriosclerosis, heart failure, renal disease, stroke, and cancer. Therefore, considerable research has been expended on the mechanism of sodium handling based on the current concepts of sodium balance. The studies have necessarily relied on relatively short-term experiments and focused on extremes of salt intake in humans. Ultra-long-term salt balance has received far less attention. We performed long-term salt balance studies at intakes of 6, 9, and 12 g/day and found that although the kidney remains the long-term excretory gate, tissue and plasma sodium concentrations are not necessarily the same and that urinary salt excretion does not necessarily reflect total-body salt content. We found that to excrete salt, the body makes a great effort to conserve water, resulting in a natriuretic-ureotelic principle of salt excretion. Of note, renal sodium handling is characterized by osmolyte excretion with anti-parallel water reabsorption, a state-of-affairs that is achieved through the interaction of multiple organs. In this review, we discuss novel sodium and water balance concepts in reference to our ultra-long-term study. An important key to understanding body sodium metabolism is to focus on water conservation, a biological principle to protect from dehydration, since excess dietary salt excretion into the urine predisposes to renal water loss because of natriuresis. We believe that our research direction is relevant not only to salt balance but also to cardiovascular regulatory mechanisms.

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Salt and Water Balance in the East African Fresh-Water Crab, Potamon Niloticus (M. Edw.)

Journal of Experimental Biology ◽

10.1242/jeb.36.1.157 ◽

1959 ◽

Vol 36 (1) ◽

pp. 157-176 ◽

Cited By ~ 3

Author(s):

J. SHAW

Keyword(s):

Water Balance ◽

Fresh Water ◽

Sea Water ◽

Freezing Point ◽

Salt Content ◽

The Body ◽

Sodium Balance ◽

East African ◽

Sodium Loss ◽

Salt And Water Balance

1. The mechanisms of salt and water balance in the East African fresh-water crab, Potamon niloticus, have been investigated. 2. The freezing-point depression of the blood is equivalent to that of a 271 mM./l. NaCl solution. 3. The animals cannot survive in solutions more concentrated than 75% sea water. Above the normal blood concentration, the blood osmotic pressure follows that of the medium. 4. The urine is iso-osmotic with the blood and is produced at a very slow rate. The potassium content is only half that of the blood. 5. The animal loses sodium at a rate of 8 µM./10 g./hr. mainly through the body surface. Potassium loss occurs at one-sixteenth of this rate. 6. Sodium balance can be maintained at a minimum external concentration of 0.05 mM./l. Potassium requires a concentration of 0.07 mM./l. 7. Active absorption of both sodium and potassium occurs. The rate of uptake of sodium depends on the extent of previous sodium loss. The rate of sodium uptake may be affected by such environmental factors as the salt content of the water, temperature and oxygen tension. 8. The normal oxygen consumption rate is 0.72 mg./10 g./hr. A minimum of 2.3% is used in doing osmotic work to maintain salt balance. 9. The salt and water balance in Potamon is discussed in relation to the adaptation of the Crustacea to fresh water. The importance of permeability changes is stressed.

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Aldosterone effects on water and electrolyte metabolism

Journal of Endocrinology ◽

10.1677/joe.0.1000093 ◽

1984 ◽

Vol 100 (1) ◽

pp. 93-100 ◽

Cited By ~ 9

Author(s):

C. J. Kenyon ◽

N. A. Saccoccio ◽

D. J. Morris

Keyword(s):

Body Weight ◽

Water Balance ◽

Urine Volume ◽

Free Water ◽

The Body ◽

Sodium Balance ◽

Plasma Sodium ◽

Transient Effects ◽

Water Metabolism ◽

Free Water Clearance

ABSTRACT The effects of constant infusions of small doses of adrenal steroid hormones on sodium, potassium and water metabolism were studied in male adrenalectomized rats. An infusion of 1 μg aldosterone/day was sufficient to restore normal sodium and potassium balance in a group of rats fed an unsupplemented diet. Log doses of aldosterone (0·1–10 μg/day for 4 days) administered some days after adrenalectomy caused linear increases in the body weight of rats fed a sodium-supplemented diet (0·05 m-NaCl as drinking fluid) during 4 days of treatment. Increases in body weight correlated with renal sodium and water balance. When steroid treatment was started at the time of adrenalectomy, sodium balance was not significantly affected although rats treated with 1 μg aldosterone/day ate more, drank less saline, produced a smaller volume of urine of greater osmolarity and gained more weight than controls. A dose of 100 μg 18-hydroxy-deoxycorticosterone/day had no significant effects. Fluid intake and urine volume were not significantly affected by 1 mg corticosterone/day but food intake, water balance and weight gain were greater than controls. Rats treated with both aldosterone and corticosterone showed a decrease in free water clearance. Aldosterone and corticosterone, both singly and in combination, reduced plasma potassium levels. Plasma sodium levels were only increased when aldosterone was administered on its own. Long-term steroid infusions have revealed more about the physiology of aldosterone action than could acute measurements of renal function. In particular, they have indicated that dietary intake of electrolytes as well as excretion are affected, that mineralocorticoid actions are distinct from glucocorticoid actions and that there are transient effects of aldosterone on fluid regulation which are not sustained under steady-state conditions. J. Endocr. (1984) 100,93–100

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Estimation of Productivity in Dryland Mediterranean Pastures: Long-Term Field Tests to Calibration and Validation of the Grassmaster II Probe

AgriEngineering ◽

10.3390/agriengineering2020015 ◽

2020 ◽

Vol 2 (2) ◽

pp. 240-255

Author(s):

João Serrano ◽

Shakib Shahidian ◽

Francisco Moral ◽

Fernando Carvajal-Ramirez ◽

José Marques da Silva

Keyword(s):

Field Tests ◽

Correlation Coefficients ◽

Growth Cycle ◽

Great Effort ◽

Long Term Study ◽

Sampling Points ◽

Capacitance Probe ◽

Favorable Period ◽

Pasture Productivity

The estimation of pasture productivity is of great interest for the management of animal grazing. The standard method of assessing pasture mass requires great effort and expense to collect enough samples to accurately represent a pasture. This work presents the results of a long-term study to calibrate a Grassmaster II capacitance probe to estimate pasture productivity in two phases: (i) the calibration phase (2007–2018), which included measurements in 1411 sampling points in three parcels; and (ii) the validation phase (2019), which included measurements in 216 sampling points in eight parcels. A regression analysis was performed between the capacitance (CMR) measured by the probe and values of pasture green matter and dry matter (respectively, GM and DM, in kg ha−1). The results showed significant correlations between GM and CMR and between DM and CMR, especially in the early stages of pasture growth cycle. The analysis of the data grouped by classes of pasture moisture content (PMC) shows higher correlation coefficients for PMC content >80% (r = 0.775; p < 0.01; RMSE = 4806 kg ha−1 and CVRMSE = 28.1% for GM; r = 0.750; p < 0.01; RMSE = 763 kg ha−1 and CVRMSE = 29.7% for DM), with a clear tendency for the accuracy to decrease when the pasture vegetative cycle advances and, consequently, the PMC decreases. The validation of calibration equations when PMC > 80% showed a good approximation between GM or DM measured and GM or DM predicted (r = 0.959; p < 0.01; RMSE = 3191 kg ha−1; CVRMSE = 23.6% for GM; r = 0.953; p <0.01; RMSE = 647 kg ha−1 and CVRMSE = 27.3% for DM). It can be concluded that (i) the capacitance probe is an expedient tool that can enable the farm manager to estimate pasture productivity with acceptable accuracy and support the decision-making process in the management of dryland pastures; (ii) the more favorable period for the use of this probe in dryland pastures in a Mediterranean climate, such as the Portuguese Alentejo, coincides with the end of winter and beginning of spring (February–March), corresponding to PMC > 80%.

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The Off-Target Effects, Electrolyte and Mineral Disorders of SGLT2i

Molecules ◽

10.3390/molecules25122757 ◽

2020 ◽

Vol 25 (12) ◽

pp. 2757 ◽

Cited By ~ 1

Author(s):

Giuseppe Cianciolo ◽

Antonio De Pascalis ◽

Lorenzo Gasperoni ◽

Francesco Tondolo ◽

Fulvia Zappulo ◽

...

Keyword(s):

Experimental Studies ◽

Sodium Balance ◽

Calcium Excretion ◽

Sodium Transporters ◽

New Class ◽

Sodium Glucose Cotransporter ◽

Natriuretic Effect ◽

Sodium Handling ◽

Target Effects

The sodium-glucose cotransporter 2 inhibitors (SGLT2i) are a relatively new class of antidiabetic drugs that, in addition to emerging as an effective hypoglycemic treatment, have been shown to improve, in several trials, both renal and cardiovascular outcomes. In consideration of the renal site of action and the associated osmotic diuresis, a negative sodium balance has been postulated during SGLT2i administration. Although it is presumable that sodium and water depletion may contribute to some positive actions of SGLT2i, evidence is far from being conclusive and the real physiologic effects of SGLT2i on sodium remain largely unknown. Indeed, no study has yet investigated how SGLT2i change sodium balance in the long term and especially the pathways through which the natriuretic effect is expressed. Furthermore, recently, several experimental studies have identified different pathways, not directly linked to tubular sodium handling, which could contribute to the renal and cardiovascular benefits associated with SGLT2i. These compounds may also modulate urinary chloride, potassium, magnesium, phosphate, and calcium excretion. Some changes in electrolyte homeostasis are transient, whereas others may persist, suggesting that the administration of SGLT2i may affect mineral and electrolyte balances in exposed subjects. This paper will review the evidence of SGLT2i action on sodium transporters, their off-target effects and their potential role on kidney protection as well as their influence on electrolytes and mineral homeostasis.

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