Water balance is one of the basic regulation mechanisms of homeostasis. There are 13 subtypes of aquaporins in mammals (AQP0-AQP12). In neural system, the AQP4 is mainly distributed in astrocytes. Phosphorylation and expression regulation of AQP4 is involved in the formation of brain edema, particularly in the clearance of vasogenic edema and the formation of cytotoxic edema. This article reviews regulations and functions of AQP4 in vasogenic edema and cytotoxic edema.
Animals ; Aquaporin 4 ; metabolism ; physiology ; Brain ; metabolism ; physiopathology ; Brain Edema ; metabolism ; physiopathology ; Homeostasis ; Humans ; Water-Electrolyte Balance ; physiology

The kidney collecting duct is an important renal tubular segment for the regulation of body water and salt homeostasis. Water reabsorption in the collecting duct cells is regulated by arginine vasopressin (AVP) via the vasopressin V2-receptor (V2R). AVP increases the osmotic water permeability of the collecting duct cells through aquaporin-2 (AQP2) and aquaporin-3 (AQP3). AVP induces the apical targeting of AQP2 and transcription of AQP2 gene in the kidney collecting duct principal cells. The signaling transduction pathways resulting in the AQP2 trafficking to the apical plasma membrane of the collecting duct principal cells, include AQP2 phosphorylation, RhoA phosphorylation, actin depolymerization and calcium mobilization, and the changes of AQP2 protein abundance in water balance disorders have been extensively studied. These studies elucidate the underlying cellular and molecular mechanisms of body water homeostasis and provide the basis for the treatment of body water balance disorders.
Actins ; Aquaporin 2* ; Aquaporins ; Arginine Vasopressin ; Body Water ; Calcium ; Cell Membrane ; Homeostasis ; Kidney Tubules, Collecting* ; Permeability ; Phosphorylation ; Vasopressins ; Water-Electrolyte Balance Body Water

BACKGROUND: EDTA was added to the formulation of propofol to inhibit microbial growth due to accidental extrinsic contamination. This study was conducted to determine whether the EDTA in the propofol would affect the ionized calcium homeostasis, other electrolyte balance, blood urea nitrogen (BUN) and creatinine (Cr) in long time craniotomy patients. METHODS: Forty two patients undergoing surgery for clipping of a cerebral aneurysm were randomly assigned to receive either propofol without EDTA (propofol group; n = 20), or propofol with EDTA (propofol EDTA group; n = 22). The ionized calcium, total calcium, total magnesium, phosphate, potassium, sodium, BUN and Cr in the blood were measured at before anesthetic induction, 4 hours after induction and 1 hour after the operation. RESULTS: There were no significant differences in the ionized calcium, other electrolytes, BUN and Cr between the two groups. CONCLUSIONS: The addition of EDTA into propofol appears to have no significant effects on the electrolyte balance, BUN and Cr concentration.
Blood Urea Nitrogen ; Calcium ; Characidae* ; Craniotomy ; Creatinine* ; Edetic Acid* ; Electrolytes ; Homeostasis ; Humans ; Intracranial Aneurysm ; Magnesium ; Potassium ; Propofol* ; Sodium ; Water-Electrolyte Balance

Adrenomedullin (AM) is a multi-functional peptide discovered in human pheochromocytoma. Initially, it was suggested that AM was synthesized only by tumor cells, however, subsequent studies revealed that it was produced also by normal adrenal medulla as well as by many other tissues. Now it is well established that AM functions as a circulating hormone and local paracrine mediator with multiple biological activities. AM stimulated cAMP production in human platelets and exerted potent and long-lasting hypotensive activity in the rat. AM is a physiologically relevant regulator in fluid and electrolyte homeostasis; inhibition both water and salt intake, increase renal blood flow, and cause diuresis and natriuresis. The up-regulation of cardiac AM system in hypertension may be a protective mechanism decreasing myocardial overload due to vasodilatory and natriuretic properties of AM, as well as limiting further myocardial hypertrophy and remodeling. AM may protect the kidney against ischemia-reperfusion injury. AM is also suggested as antiapoptotic, anti-inflammatory and angiogenic factor. In this review, I offer a review of our current knowledge on AM and give the putative role of AM in water-electrolyte balance, hypertension and kidney disease.
Adrenal Medulla ; Adrenomedullin* ; Angiogenesis Inducing Agents ; Animals ; Diuresis ; Homeostasis ; Humans ; Hypertension ; Hypertrophy ; Kidney Diseases ; Kidney* ; Natriuresis ; Pheochromocytoma ; Rats ; Renal Circulation ; Reperfusion Injury ; Up-Regulation ; Water-Electrolyte Balance

Intraperitoneal hyperthermic perfusion(IPHP) is gaining popularity in the world as a method of prevention and treatment of peritoneal metastasis following gatrointestinal cancer. The procedure presents significant problems to the anesthegiologist with regard to tempera- ture control, fluid and electrolyte balance, acid-base change and postoperative care. During IPHP, there is a potential for heat gain from the peritoneal cavity. Several workers have reported a significant increase in core temperature. Therefore, it is true that accurate monitoring of temperature is essential. We studied that acid-base balance, electrolyte balance, level of blood suger following core temperature change in Intraperitoneal Hyperthermo-chemotherapeutic Perfusion patients.
Acid-Base Equilibrium ; Anesthesia* ; Hot Temperature ; Humans ; Neoplasm Metastasis ; Perfusion* ; Peritoneal Cavity ; Postoperative Care ; Stomach Neoplasms* ; Stomach* ; Water-Electrolyte Balance

PURPOSE: Antenatal steroid (AS) may result in lower insensible water loss (IWL), and higher urine output (UO) in early life. We examined if the postnatal fluid balance differed between infants exposed to AS or not (control) in VLBW infants. METHODS: Fifty-four VLBW infants were grouped into AS (n=24) or control (n=30). Fluid intake, UO, IWL and maximal % of weight loss on day 1, day 2, day 3 and day 7 after birth were analyzed. Daily maintenance fluid was determined in each infants by calculation of insensible water loss (IWL=[intake-output]-Delta wt) and UO. RESULTS: Fluid intake (AS vs control; 117.2+/-33.9 vs 126.0+/-29.6 mL/kg/d, P=0.315), IWL (28.1+/-23.7 vs 21.1+/-20.5 P=0.248), UO and maximal % of weight loss on day 7 were not different between groups: similar findings were observed on day 1, day 2, and day 3 after birth. Neonatal morbidities and clinical relevant factors were not different between groups. The duration of assisted ventilation was shorter in the AS than in the control (10.8+/-9.2 vs 27.6+/-26.2, P=0.002). However, the difference disappeared after adjustment for RDS severity and oxygenation index. CONCLUSION: VLBW infants exposed to AS did not have an alteration in postnatal fluid balance during the first week of life, when given fluid based on needs reflected by IWL and UO. The decreased need for assisted ventilation in the AS group may be related to the effects of steroid on fetal lung fluid absorption or maturity, but not on postnatal fluid balance.
Absorption ; Humans ; Infant* ; Infant, Very Low Birth Weight* ; Lung ; Oxygen ; Parturition ; Ventilation ; Water Loss, Insensible ; Water-Electrolyte Balance* ; Weight Loss

The kidneys play a key role in the homeostasis of body water and electrolyte balance. Aquaporin-2 (AQP2) is the vasopressin-regulated water-channel protein expressed at the connecting tubule and collecting duct, and plays a key role in urine concentration and body-water homeostasis through short-term and long-term regulation of collecting duct water permeability. The signaling transduction pathways resulting in the AQP2 trafficking to the apical plasma membrane of the collecting duct principal cells, including AQP2 phosphorylation, RhoA phosphorylation, actin depolymerization, and calciumm obilization, and the changes of AQP2 abundance in water-balance disorders have been extensively studied. Dysregulation of AQP2 has been shown to be importantly associated with a number of clinical conditions characterized by body-water balance disturbances, including hereditary nephrogenic diabetes insipidus (NDI), lithium-induced NDI, electrolytes disturbance, acute and chronic renal failure, ureteral obstruction, nephrotic syndrome, congestive heart failure, and hepatic cirrhosis. Recent studies exploiting omics technology further demonstrated the comprehensive vasopressin signaling pathways in the collecting ducts. Taken together, these studies elucidate the underlying molecular mechanisms of body-water homeostasis and provide the basis for the treatment of body-water balance disorders.
Actins ; Aquaporin 2* ; Aquaporins ; Arginine Vasopressin ; Body Water ; Cell Membrane ; Diabetes Insipidus, Nephrogenic ; Electrolytes ; Heart Failure ; Homeostasis* ; Kidney Failure, Chronic ; Kidney* ; Liver Cirrhosis ; Nephrotic Syndrome ; Permeability ; Phosphorylation ; Ubiquitination ; Ureteral Obstruction ; Urine ; Vasopressins ; Water-Electrolyte Balance

The kidney and the brain play a major role in maintaining normal homeostasis of the extracellular fluid by neuroendocrine regulation of sodium and water balance. Therefore, disturbances of sodium balance are common in patients with central nervous system (CNS) disorders and clinicians should focus not only on the CNS lesion, but also on the potentially deleterious complications. Hyponatremia is the most common and important electrolyte disorder affecting patients with critical neurologic diseases. In these patients, the maladaptation to hyponatremia by impaired osmoregulation in pathologic lesions of brain may cause more aggressive cerebral edema and increased intracranial pressure due to hypoosmolality induced by hyponatremia. Furthermore, hyponatremia accompanied by CNS disorders has shown to increase delayed cerebral ischemia and mortality rates. Two main pathophysiologies of hyponatremia, excluding iatrogenic causes, are inappropriate secretion of antidiuretic hormone (SIADH) and cerebral salt wasting (CSW) syndrome. Differential diagnosis between these two entities can be difficult due to considerable overlap in the laboratory findings and clinical situations. SIADH is in a volume expanded status due to inappropriately secreted arginine vasopressin (AVP) and requires water restriction. However, CSW syndrome is characterized by renal sodium wasting mainly due to increased natriuretic peptides resulting in volume depletion and follows appropriate secretion of AVP. Therefore, maintenance of volume status and sodium replacement is the mainstay of treatment in CSW syndrome. In this review, we aimed to describe the regulation of sodium and water balance, and pathophysiology, diagnosis and treatment of hyponatremia in neurologic patients, especially focusing on SIADH and CSW syndrome.
Arginine Vasopressin ; Brain ; Brain Edema ; Brain Ischemia ; Central Nervous System ; Diagnosis, Differential ; Extracellular Fluid ; Homeostasis ; Humans ; Hyponatremia ; Inappropriate ADH Syndrome ; Intracranial Pressure ; Kidney ; Natriuretic Peptides ; Nervous System Diseases ; Sodium ; Water-Electrolyte Balance

BACKGROUND AND OBJECTIVES: The inner ear is an organ used for hearing and balance. For its normal function, the inner ear fluid homeostasis is required. There has been controversy over the regulatory mechanisms of maintaining inner ear fluid balance, and they have not yet been clearly defined. TonEBP is the protein that binds tonicity-responsive enhancer elements in the osmoprotective gene, which elevates the compatible osmolytes, which in turn induces cell survival in hypertonic condition. The aim of this study was to elucidate if there is an osmoregulatory mechanism in cochlea. Material and Method: The localization of TonEBP in the cochlea of male Sprague-Dawley rats was studied by immunohistochemistry with an anti rabbit polyclonal anti-rat TonEBP antibody. RESULTS: TonEBP was expressed at outer hair cells, Deiter cells, spiral ligaments, sprial limbus connective tissues, and epithelial lining of basilar membrane facing scala tympani. CONCLUSION: TonEBP in cochlea is one of the proteins involved in elucidating cell survival in changed tonicity during inner ear homeostasis.
Animals ; Basilar Membrane ; Carrier Proteins* ; Cell Survival ; Cochlea* ; Connective Tissue ; Ear, Inner ; Enhancer Elements, Genetic ; Hair ; Hearing ; Homeostasis ; Humans ; Immunohistochemistry ; Male ; Rats* ; Rats, Sprague-Dawley ; Scala Tympani ; Spiral Ligament of Cochlea ; Water-Electrolyte Balance

PURPOSE: Extremely-low-birth-weight infants (ELBWIs), especially those < or =24 gestational weeks (GW), presented extremes in IWL and changes of water balance. The purpose of the present study was to retrospectively investigate fluid and electrolyte balance in infants of < or =24-GW during the first postnatal week under high humidification. METHODS: Medical records of extremely-low-birth-weight infants (ELBWIs) who were born and admitted to the Neonatal Intensive Care Unit at Samsung Medical Center during March 2004-September 2010 were reviewed. Fluid intake, urine output, insensible water loss (IWL), and electrolyte balance of 22-GW (n=14), 23-GW (n=40), and 24-GW (n=67) infants nursed in high humidity (95%) were compared with > or =26-GW (n=65) infants nursed in 60% humidity. RESULTS: Survival rate until discharge was 33%, 82%, 75%, and 89.3% in 22-GW, 23-GW, 24-GW, and > or =26-GW infants, respectively. Fluid intake and IWL was higher in 22-GW and 23-WG, but not different in 24-GW, than in > or =26-GW infants. At postnatal days (P) 3-5, the urine output was significantly lower in > or =26-GW infants than in the other age groups. Serum sodium level was significantly higher in 22-, 23-, and 24-GW (P1-2) than in > or =26-GW infants. Hypernatremia (>150 mEq/dl sodium) was more frequent in 22-GW (71%), 23-GW (41%), and 24-GW (21%) than in > or =26-GW infants (14%). CONCLUSION: High-humidity environments significantly decreased fluid intake and improved electrolyte imbalance in 24-GW, but not 22- and 23-GW, infants. Increased IWL in the latter might be related to more immature skin, and implicates the need for additional nurturing conditions.
Apnea ; Electrolytes ; Humans ; Humidity ; Hypernatremia ; Infant ; Infant, Newborn ; Infant, Premature ; Intensive Care, Neonatal ; Medical Records ; Retrospective Studies ; Seizures ; Skin ; Sodium ; Survival Rate ; Water Loss, Insensible ; Water-Electrolyte Balance