Studies of the sodium, chloride and water balance of Xiphister atropurpureus (Evans, 1967 a-c) showed that this intertidal teleost is relatively impermeable to these ions and to water, has an exchange-diffusion system for sodium only, and apparently lowers its permeability to sodium but not to chloride or water when acclimated to a lower salinity. An investigation of the intertidal teleost, Pho...

Disorders of water balance lead either to dehydration or overhydration. Because there is an intimate relationship between water and sodium concentration (water generally following salt), one can distinguish hypotonic, isotonic and hypertonic dehydration and the same for overhydration. The vast majority of water balance disorders are acquired. In this article, the focus is on the inherited disor...

Disorders of water balance lead either to dehydration or overhydration. Because there is an intimate relationship between water and sodium concentration (water generally following salt), one can distinguish hypotonic, isotonic and hypertonic dehydration and the same for overhydration. The vast majority of water balance disorders are acquired. In this article, the focus is on the inherited disor...

Changes in gravitational load have been shown to alter renal function, which could potentially affect water balance. Therefore, the present study was conducted to determine the effects of chronic centrifugation on water balance. Eight Sprague-Dawley rats were centrifuged (12 days at 2 G), and eight rats were used as a control group. Water balance over the course of the study was determined by q...

The effect on water and electrolyte balance of stress, simulated by intravenous infusion of cortisol, was studied using 24 18-mo-old Merino wethers (37.0 +/- 0.94 kg mean body weight [BW]) over 72 h. The sheep were allocated to one of four groups: 1) no water/no cortisol (n = 6); 2) water/no cortisol (n = 4); 3) no water/cortisol (n = 6); and 4) water/cortisol (n = 4). Animals allocated to the ...

The renin-angiotensin-aldosterone system (RAAS) appears to contribute significantly to osmoregulation of fasting northern elephant seal (Mirounga angustirostris) pups; however, RAAS has not been characterized in fasting adult seals. Therefore, this study examined the contribution of RAAS to water turnover rates in fasting adult male northern elephant seals. Blood samples were obtained twice dur...

WATER BALANCE IN TELEOST FISH IS MAINTAINED WITH CONTRIBUTIONS FROM THE MAJOR OSMOREGULATORY ORGANS: intestine, gills, and kidney. Overall water fluxes have been studied in all of these organs but not until recently has it become possible to approach the mechanisms of water transport at the molecular level. This mini-review addresses the role of the kidney in osmoregulation with special emphasi...

One of the aspects of insect osmoregulation that has most intrigued researchers is the ability of a simple tubular epithelium, such as the Malpighian tubule, to create both hypo- and hyperosmotic urine. Indeed, Ramsay's initial observation that isolated tubules could secrete a hypoosmotic urine led him to attribute the phenomenon to the active transport of water. In the ensuing decades several ...

Water-Electrolyte Balance in Blood Pressure Homeostasis Much of what human life is about is water (60% of body mass) and a handful of solutes. Of the latter, main cations include sodium, potassium, calcium, and magnesium, and the anions include chloride, bicarbonate, phosphate and organic anions, and proteins. The concentrations of sodium (135–145 mmol/L) and chloride (95–106 mmol/L) predominat...

The analysis of soil water partitioning in seasonally dry climates necessarily requires careful consideration of the periodic climatic forcing at the intra-annual timescale in addition to daily scale variabilities. Here, we introduce three new extensions to a stochastic soil moisture model which yields seasonal evolution of soil moisture and relevant hydrological fluxes. These approximations al...