Disorders of Water and Sodium Balance

2014 ◽  
Author(s):  
Richard H Sterns
Keyword(s):  
Water Conservation ◽  
Body Fluid ◽  
Cell Volume Regulation ◽  
Extracellular Fluid ◽  
Sodium Balance ◽  
Sodium Reabsorption ◽  
Renal Tubules ◽  
Response Curves ◽  
Volume Depletion ◽  
Fluid Compartment

Water accounts for approximately half of an adult human’s body weight. Two thirds of body water is intracellular, and the remaining one third is contained in the extracellular fluid compartment, which includes intravascular (plasma) and interstitial fluid. Small amounts of water are also contained in bone, dense connective tissue, digestive secretions, and cerebrospinal fluid. To maintain the stability of the internal milieu, body fluids are processed by the kidney, guided by intricate physiologic control systems that regulate fluid volume and composition. This chapter reviews the regulation of body fluid volumes, cell volume regulation in hypotonicity and hypertonicity, disorders of water excess (hyponatremia), water deficiency (hypernatremia), water conservation (diabetes insipidus), saltwater excess (edematous states), and saltwater deficiency (volume depletion). Tables describe control of body fluid volumes, causes of nonhypotonic hyponatremia, causes and treatment of acute hyponatremia, causes of the syndrome of inappropriate release of antidiuretic hormone (SIADH), and causes of hypernatremia. Figures illustrate sodium reabsorption by the renal tubules, the relationship between plasma vasopressin levels, renal sodium handling, and dose-response curves for a loop diuretic in patients with normal and reduced renal function. This chapter contains 4 highly rendered figures, 5 tables, 88 references, and 5 MCQs.

Quantitative relationship of renal glucose and sodium reabsorption during ECF expansion

1975 ◽  
Vol 229 (1) ◽  
pp. 66-71 ◽  
Author(s):  
Higgins JT ◽  
AE Meinders
Keyword(s):  
Proximal Tubule ◽  
Isotonic Saline ◽  
Extracellular Fluid ◽  
Quantitative Relationship ◽  
Ringer Solution ◽  
Sodium Balance ◽  
Sodium Reabsorption ◽  
Coupled Transport ◽  
Appearance Time ◽  
Glucose Reabsorption

To investigate the quantitative relationship between glucose and sodium reabsorption during extracellular fluid (ECF) expansion and to examine the possible contribution to glucosuria of passive diffusion of glucose from peritubular blood to tubular fluid, renal clearance studies were carried out in dogs. It was found that ECF expansion with isotonic saline or Ringer solution causes a decrease in the maximal rate of glucose reabsorption (TmGlc), which is inversely and linearly related to fractional sodium excretion (FENa) over a range from less than 1% more than 25% FENa (r equals -0.394, P less than 0.001). A continuous relationship between TmGlc and FENa could be demonstrated as the ECF was expanded in individual animals as well as in pooled data. Infusion of albumin solution to preferentially expand the plasma volume and decrease proximal tubular sodium reabsorption produced a 24% fall in TmGlc suggesting that the proximal tubule is the site of interrelated glucose and sodium reabsorption. After pulse injections into the renal artery, [14-C]glucose and insulin had the same appearance time in the urine, thus failing to demonstrate diffusion of glucose from blood into the tubule in saline-loaded dogs as well as in dogs in normal sodium balance. It is suggested that ECF expansion exerts its effect on glucose reabsorption by inhibiting the coupled transport of glucose and sodium across the epithelium of the renal proximal tubule.

Urinary system

2021 ◽  
pp. 497-534
Keyword(s):  
Body Fluid ◽  
Obstructive Uropathy ◽  
Extracellular Fluid ◽  
Mechanisms Of Action ◽  
Urinary Continence ◽  
Renal Tubules ◽  
Urinary System ◽  
Bladder Control ◽  
System P ◽  
Body Fluid Homeostasis

The ‘Urinary system’ chapter opens with a description of the urinary tract morphology (kidney, ureters, bladder) and its histology. Renal function is considered, including glomerular filtration, the role and regulation of the renal tubules in producing dilute and concentrated urines, and the mechanisms of action of diuretic drugs. The function of the kidney in body fluid homeostasis (extracellular fluid volume and osmolarity, pH) is then discussed, and the regulation of kidney function explored, including bladder control and urinary continence. Finally, renal failure and obstructive uropathy are discussed as examples of renal pathology.

scholarly journals Vasopressin V2 receptors, ENaC, and sodium reabsorption: a risk factor for hypertension?

2010 ◽  
Vol 299 (5) ◽  
pp. F917-F928 ◽  
Author(s):  
Lise Bankir ◽  
Daniel G. Bichet ◽  
Nadine Bouby
Keyword(s):  
Blood Pressure ◽  
Risk Factor ◽  
Water Conservation ◽  
Sodium Excretion ◽  
Sodium Balance ◽  
Sodium Reabsorption ◽  
Acute Administration ◽  
Receptor Stimulation ◽  
V2 Receptor

Excessive sodium reabsorption by the kidney has long been known to participate in the pathogenesis of some forms of hypertension. In the kidney, the final control of NaCl reabsorption takes place in the distal nephron through the amiloride-sensitive epithelial sodium channel (ENaC). Liddle's syndrome, an inherited form of hypertension due to gain-of-function mutations in the genes coding for ENaC subunits, has demonstrated the key role of this channel in the sodium balance. Although aldosterone is classically thought to be the main hormone regulating ENaC activity, several studies in animal models and in humans highlight the important effect of vasopressin on ENaC regulation and sodium transport. This review summarizes the effect of vasopressin V2 receptor stimulation on ENaC activity and sodium excretion in vivo. Moreover, we report the experimental and clinical data demonstrating the role of renal ENaC in water conservation at the expense of a reduced ability to excrete sodium. Acute administration of the selective V2 receptor agonist dDAVP not only increases urine osmolality and reduces urine flow rate but also reduces sodium excretion in rats and humans. Chronic V2 receptor stimulation increases blood pressure in rats, and a significant correlation was found between blood pressure and urine concentration in healthy humans. This led us to discuss how excessive vasopressin-dependent ENaC stimulation could be a risk factor for sodium retention and resulting increase in blood pressure.

Increasing or stabilizing renal epoxyeicosatrienoic acid production attenuates abnormal renal function and hypertension in obese rats

2007 ◽  
Vol 293 (1) ◽  
pp. F342-F349 ◽  
Author(s):  
Hui Huang ◽  
Christophe Morisseau ◽  
JingFeng Wang ◽  
Tianxin Yang ◽  
John R. Falck ◽  
...  
Keyword(s):  
Renal Hemodynamics ◽  
Male Rats ◽  
Sodium Balance ◽  
Sodium Reabsorption ◽  
Dodecanoic Acid ◽  
Peroxisome Proliferator ◽  
Induction Effect ◽  
Renal Tubules ◽  
Renal Vasculature ◽  
Renal Vascular

Since epoxyeicosatrienoic acids (EETs) affect sodium reabsorption in renal tubules and dilate the renal vasculature, we have examined their effects on renal hemodynamics and sodium balance in male rats fed a high-fat (HF) diet by fenofibrate, a peroxisome proliferator-activated receptor-α (PPAR-α) agonist and an inducer of cytochrome P-450 (CYP) epoxygenases; by N-methanesulfonyl-6-(2-proparyloxyphenyl)hexanamide (MSPPOH), a selective EET biosynthesis inhibitor; and by 12-(3-adamantane-1-yl-ureido)dodecanoic acid (AUDA), a selective inhibitor of soluble epoxide hydrolase. In rats treated with fenofibrate (30 mg·kg−1·day−1 ig) or AUDA (50 mg/l in drinking water) for 2 wk, mean arterial pressure, renal vascular resistance, and glomerular filtration rate were lower but renal blood flow was higher than in vehicle-treated control rats. In addition, fenofibrate and AUDA decreased cumulative sodium balance in the HF rats. Treatment with MSPPOH (20 mg·kg−1·day−1 iv) + fenofibrate for 2 wk reversed renal hemodynamics and sodium balance to the levels in control HF rats. Moreover, fenofibrate caused a threefold increase in renal cortical CYP epoxygenase activity, whereas the fenofibrate-induced elevation of this activity was attenuated by MSPPOH. Western blot analysis showed that fenofibrate induced the expression of CYP epoxygenases in renal cortex and microvessels and that the induction effect of fenofibrate was blocked by MSPPOH. These results demonstrate that the fenofibrate-induced increase of CYP epoxygenase expression and the AUDA-induced stabilization of EET production in the kidneys cause renal vascular dilation and reduce sodium retention, contributing to the improvement of abnormal renal hemodynamics and hypertension in HF rats.

Fluid and electrolyte physiology in anaesthetic practice

2017 ◽  
Author(s):  
Robert G. Hahn
Keyword(s):  
Blood Volume ◽  
Body Fluid ◽  
Extracellular Fluid ◽  
Haemorrhagic Shock ◽  
The Body ◽  
Intracellular Space ◽  
Fluid Compartment ◽  
Life Saving ◽  
Total Body ◽  
Infusion Fluid

The maintenance of body fluid homeostasis is an essential task in perioperative care. Body fluid volumes are tightly controlled by the nervous system, by hormones, and by the kidneys. All these systems are affected by anaesthesia and surgery in ways that must be appreciated by the anaesthetist. Administration of infusion fluids is the key tool to prevent major derangements of the body fluid volumes during before, during, and after surgery. By varying its composition, an infusion fluid can be made to selectively expand or shrink a body fluid compartment. The total osmolality determines whether the infused volume distributes over the total body water or over the extracellular fluid volume, or even attracts fluid from intracellular space. Infusion fluid is the first-line tool in the management of the vasodilation that is induced by both general and regional anaesthesia. Fluids are also an essential component in the treatment of haemorrhage, in which a reduction in arterial pressure implies that 20% of the blood volume has been lost. Capillary refill restores the blood volume, but too slowly to prevent haemorrhagic shock. In this situation, prompt intravenous fluid therapy is life-saving. Electrolyte derangements may be induced by disease and/or medication. The most essential ones to consider during anaesthesia are sodium, potassium, calcium, and bicarbonate.

Mechanism of natriuresis following intravascular and extracellular volume expansion

1969 ◽  
Vol 47 (2) ◽  
pp. 153-159 ◽  
Author(s):  
H. Sonnenberg ◽  
S. Solomon
Keyword(s):  
Blood Volume ◽  
Volume Expansion ◽  
Filtration Rate ◽  
Extracellular Volume ◽  
Extracellular Fluid ◽  
Sodium Reabsorption ◽  
Fluid Compartment ◽  
Proximal Tubular ◽  
Extracellular Volume Expansion ◽  
A Site

In clearance studies in rats, increases in filtration rate and electrolyte excretion were observed following both intravascular and extracellular fluid volume expansion. The inulin concentration ratio of proximal tubular fluid to plasma was decreased with extracellular expansion. Neither natriuresis nor fractional sodium reabsorption was related to the degree of intravascular expansion. Microperfusion studies demonstrated a decrease in proximal sodium reabsorption only when both intravascular and extravascular volumes were expanded; net sodium transport was not affected by a blood volume increase alone. From the data it is concluded that in the rat an increase in blood volume is followed by a rise of filtration rate and a fall of fractional reabsorption at a site distal to the proximal tubule, resulting in diuresis and natriuresis. If, in addition, the interstitial fluid compartment is expanded, a direct inhibition of the active transport component of proximal Na+ reabsorption occurs.

Clinical use of diuretics

2015 ◽  
Author(s):  
David H. Ellison ◽  
Arohan R. Subramanya
Keyword(s):  
Proximal Tubule ◽  
Collecting Duct ◽  
Extracellular Fluid ◽  
Chronic Administration ◽  
Distal Convoluted Tubule ◽  
Loop Diuretics ◽  
Sodium Reabsorption ◽  
Thick Ascending Limb ◽  
Response Curves ◽  
Collecting Tubules

Diuretics are widely employed to treat extracellular fluid volume expansion caused by heart failure, cirrhosis of the liver, nephrotic syndrome, and chronic kidney disease. Major classes of diuretic inhibit sodium reabsorption along the proximal tubule, the loop of Henle, the distal convoluted tubule, and the connecting and collecting tubules. Loop diuretics have the highest ceiling of action and often form the cornerstones of diuretic treatment of oedema. Members of this class are short-acting drugs, with different bioavailabilities, the specifics of which contribute importantly to a rational and effective approach to their use. They are not filtered substantially because they are all protein bound. They enter tubules by secretion along the proximal tubule, thereby gaining access to the Na-K-2Cl cotransporter of the thick ascending limb. Their dose–response curves are sigmoidal and altered by several disease processes. Chronic administration can elicit adaptive processes along the nephron that limit their efficacy. Distal convoluted tubule diuretics, such as the thiazides, inhibit NaCl absorption along the distal convoluted tubule. While used predominantly to treat hypertension, they are also useful to treat oedema, especially when combined with loop diuretics. Drugs acting along the connecting tubule and collecting duct either inhibit Na+ channels directly or block mineralocorticoid receptors. These drugs are effective in states of very high aldosterone secretion, and can also be used to reduce the hypokalaemia caused by other classes of diuretics. An evidence-based approach to treating the oedematous patient is described.

Body fluid and hematologic adjustments during resting heat acclimation in rhesus monkey

1980 ◽  
Vol 49 (3) ◽  
pp. 431-437 ◽  
Author(s):  
I. R. Oddershede ◽  
R. S. Elizondo
Keyword(s):  
Rhesus Monkey ◽  
Body Fluid ◽  
Interstitial Fluid ◽  
Cell Mass ◽  
Heat Exposure ◽  
Extracellular Fluid ◽  
Heat Acclimation ◽  
Fluid Volume ◽  
Fluid Shift ◽  
Fluid Compartment

The purpose of this study was to examine body fluid adjustments during prolonged resting heat exposure in primates. Rhesus monkeys were acclimated for 35 days at 35 degrees C and 30% rh. Red cell mass, extracellular fluid volume (ECF), and total body water (TBW) were determined with 51Cr, 35SO4, and 3H2O, respectively, prior to and at intervals during heat exposure. Heat acclimation was characterized by a fluid shift from the interstitial compartment. In relation to TBW, interstitial fluid volume and ECF decreased 10.3 and 8.3%, respectively, while plasma volume (PV) and intracellular fluid were increased an average of 5.8 and 3.8%. TBW increased 4.8% during heat exposure. Hematocrit and hemoglobin decreased significantly on day 3 (7.9 and 6.5%) followed by a return toward control values. PV in relation to TBW remained elevated throughout the exposure. An increased drinking (25.0%) was associated with a decrease in caloric intake (30.7%) during heat acclimation. This study has provided a complete body fluid compartment analysis during resting heat acclimation in the rhesus monkey. Our results are consistent with the hypothesis that heat acclimation in primates is characterized by a protein and fluid shift from the interstitial fluid compartment to the cardiovascular system and to the intracellular compartment.

Sodium balance in pregnancy

1989 ◽  
Vol 1 (2) ◽  
pp. 193-212 ◽  
Author(s):  
Mark A Brown
Keyword(s):  
Plasma Volume ◽  
Important Determinant ◽  
Extracellular Fluid ◽  
Maternal Plasma ◽  
Fetal Outcome ◽  
Sodium Balance ◽  
Major Cation ◽  
Fluid Compartment ◽  
Body Sodium ◽  
In Pregnancy

Sodium is the major cation in the extracellular fluid volume (ECFV) and as such, is the most important determinant of osmolality and of the volume of this fluid compartment. Hence any alteration in the control of body sodium will be reflected by changes in the ECFV, including the maternal plasma volume. There is no doubt that expansion of the plasma volume is a necessary and desirable event during pregnancy, influencing positively both maternal and fetal outcome. Therefore, studies of sodium balance in pregnancy provide important information relevant to both mother and fetus.

Preoptic recess lesions, body fluid compartments, and the renin-aldosterone system

1983 ◽  
Vol 245 (6) ◽  
pp. R901-R905 ◽  
Author(s):  
S. L. Bealer ◽  
E. G. Schneider
Keyword(s):  
Plasma Volume ◽  
Sodium Excretion ◽  
Total Body Water ◽  
Body Fluid ◽  
Third Ventricle ◽  
Extracellular Fluid ◽  
Body Water ◽  
Fluid Distribution ◽  
Volume Depletion ◽  
Total Body

The effects of electrolytic ablation of the periventricular tissue surrounding the anteroventral third ventricle (AV3V) of the rat brain on body fluid distribution and the renin-aldosterone system were determined. Rats underwent either ablation of AV3V periventricular tissue or control surgeries. After recovery, animals were implanted with femoral arterial and jugular venous catheters, and sodium space and plasma volume were measured by calculating the dilution of intravenous injections of 22Na- and 125I-labeled serum albumin, respectively. Total body water was determined in separate groups of rats by desiccation. Other animals with AV3V lesions and control rats were used to measure urinary sodium excretion and plasma renin (Prenin) and aldosterone (Paldo) concentrations while volume replete and after volume depletion. Animals with AV3V lesions had expanded extracellular fluid volume and decreased plasma volume, but total body water was comparable with control-operated rats. Volume-replete and volume-depleted rats with AV3V lesions had significantly higher Prenin than control animals in similar volume states. Although Paldo was not different between groups in the volume-replete state, it was significantly greater in rats with AV3V lesions than in control animals after volume depletion. These data demonstrate that AV3V periventricular ablation results in chronic alterations in the normal body fluid distribution but does not diminish the rats' ability to increase Prenin and Paldo or decrease sodium excretion during volume depletion.

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