Salt homeostasis

Monin, Yu.G., Goncharevskaya, O.A. and Stolbov, A.Ya. (1989). The relationship between water-salt homeostasis and tissue respiration under varying muscle loading in horse-mackerel (In Russian). Vopmsy Ikhtiologii 29,842-847. 

Natochin, Yu.V. (1988). Some principles of the evolution of functions at cell, organ and organismic levels with reference to the kidney and water-salt homeostasis. Zhumal Obshchey Biologii 49,291-305. 

As a class of tissue, epithelia demarcate body entry points, predisposing a general barrier function with respect to solute entry and translocation. The intestine is lined with enterocytes, which are polarized cells with their apical membrane facing the intestinal lumen that is separated by tight junctions from the basolateral membrane that faces the subepithelial tissues. In addition to their barrier function, the epithelia that line the GI tract serve specialized functions that promote efficient nutrient digestion and absorption and support other organs of the body in water, electrolyte, and bile salt homeostasis. The homeostatic demand on GI tissue that results from this dual function may pose special transport consideration compared with solute translocation across biologically inert barriers. 

Mineralocorticoid refers to those steroids that regulate salt homeostasis (sodium conservation and potassium loss) and extracellular fluid volume.Aldosterone is the most potent naturally occurring mineralocorticoid and is synthesized exclusively in the zona glomerulosa region of the adrenal cortex. This zone uniquely contains the enzyme aldosterone synthase, an obligatory enzyme in the synthetic pathway to aldosterone. Other adrenocortical steroids that have mineralocorticoid properties with varying degrees of potency include DOC, 18-hydroxy-DOC, corticosterone,... 

SNPs in many classes of transporter genes are known, particularly among those involved in bile salt homeostasis [212], Polymorphisms in P-gp have also been identified and are thought in part to contribute to variability in P-gp function. However, insufficient studies have thus far been conducted to establish distinct roles for SNPs [213],... 

Walking difficulty 344 Water-salt homeostasis 569 Water-sodium disequilibrium 552 Weakness... 

Toad bufadienolides occur not only by themselves but also in a conjugated form, sulfates, dicarboxylic esters and amino acid-dicarboxylic acid esters have all been reported (Steyn and van Heerden 1998). Because of the activity of the bufadienolides in inhibiting active monovalent cation transporters, it is suggested that these compounds have a role in maintaining sodium homeostasis in toads that migrate between fresh and salt water environments (Flier, I idwards, Daly and Myers 1980). 

Like nitric oxide, the discovery of the eicosanoid signalling molecules was a significant event in twentieth century physiology, due largely to research led by Sir John Vane (Nobel Prize 1982). The diverse actions of the eicosanoids include roles in muscle contraction, blood coagulation, salt and fluid homeostasis, inflammatory responses and pain sensitivity. 

Hormones are intercellular messengers. They are typically (1) steroids (e.g., estrogens, androgens, and mineral corticoids, which control the level of water and salts excreted by the kidney), (2) polypeptides (e.g., insulin and endorphins), and (3) amino acid derivatives (e.g., epinephrine, or adrenaline, and norepinephrine, or noradrenaline). Hormones maintain homeostasis—the balance of biological activities in the body for example, insulin controls the blood glucose level, epinephrine and norepinephrine mediate the response to the external environment, and growth hormone promotes normal healthy growth and development. 

Mulet JM, Leube MP, Kron SJ, Rios G, Fink GR, Serrano R (1999) A novel mechanism of ion homeostasis and salt tolerance in yeast the Hal4 and Hal5 protein kinases modulate the Trkl-Trk2 potassium transporter. Mol Cell Biol 19 3328-3337... 

Natriuretic peptides (NPs) are a group of peptide hormones in animals that are critically involved in salt and water homeostasis (for review see [5]). NPs include atrial NP (ANP), brain NP (BNB), C-type NP (CNP), and urodilatin all of which are synthesized as larger precursor proteins. In... 

This effect could have reflected involvement of prolactin in adrenal steroidogenesis or salt and water homeostasis. 

A variety of renal diseases may interfere with the kidney s critical role in volume homeostasis. Although renal disorders will occasionally cause salt wasting, most kidney diseases cause retention of salt and water. When loss of renal function is severe, diuretic agents are of little benefit, because there is insufficient glomerular filtration to sustain a natriuretic response. However, a large number of patients with milder degrees of renal insufficiency can be treated with diuretics when they retain sodium. 

Although the stratum corneum acts as a simple physical barrier to outside influences, skin tissue as a whole is very active. It is crucial in maintaining the body s homeostasis, its essential steady-state environment. Skin maintains temperature and balance of electrolytes, the dissolved salts in internal body fluids. It is metabolically active and participates in hormonal and immune regulatory processes. More than serving as a passive barrier, it is proactive in response to xenobiotic insults and can be damaged in the defensive process by developing rashes and other symptoms. 

Topical application of an ionic polymer forms a diffusion electric double layer on the surface of the skin. We evaluated the effects of topical application of ionic polymers on the recovery rate of the skin barrier after injury. Application of a nonionic polymer did not affect the barrier recovery. Application of sodium salts of anionic polymers accelerated the barrier recovery, while that of cationic polymers delayed it. Topical application of a sodium-exchange resin accelerated the barrier recovery, but application of a calcium-exchange resin had no effect, even when the resins had the same structure. Application of a chloride-exchange resin delayed barrier recovery. Thus, topical application of ionic polymers markedly influenced skin barrier homeostasis (Figure 15.2). 

ABCA1 mediates the first step in the energy-dependent efflux of cholesterol from the cell to form HDL for reverse cholesterol transport (Fig. 15-2). While all tissues in the body can synthesize cholesterol, only the liver and steroidogenic tissues can metabolize it. Surplus cholesterol in cells of the peripheral tissues is transported to the liver for either redistribution to other cells or for excretion either as free cholesterol or as a bile salt after conversion in the liver. Therefore, this reverse cholesterol transport system plays a pivotal role in cholesterol homeostasis with HDL as one of the key players. 

The incidence of classic CAH-P450c21 in the United States ranges from 1 10,000 to 1 18,000, with approximately 75% of patients with CAH-P450c21 exhibiting classic salt wasting (White and Speiser, 2000). Aldosterone is essential for normal sodium homeostasis and acts to enhance sodium absorption and potassium excretion (Fig. 33-3). In the relative absence of aldosterone, there is an increase in sodium loss... 

Q7 Calcium is present in both intracellular fluid (ICF) and ECF, but the concentration in the ECF is twice as high as that in the ICF. Calcium is found in both ionized and bound forms, and Ca2+ homeostasis is mainly controlled by parathyroid hormone, which increases absorption of calcium in the intestine and reabsorption in the nephron. Calcitonin also affects ECF calcium concentration by promoting renal excretion when there is an excess of calcium in the body. The normal kidney filters and reabsorbs most of the filtered calcium however, in renal disease this is reduced and blood calcium decreases. Calcium and phosphate imbalance can occur in patients with renal failure, leading to osteomalacia (defective mineralization of bone). Osteomalacia is mainly due to reduced production of 1,25-dihydroxycholecalciferol, an active form of vitamin D metabolized in the kidney. Deficiency of 1,25-dihydroxycholecalciferol reduces the absorption of calcium salts by the intestine. 

Copper ion homeostasis in prokaryotes involves Cu ion efflux and sequestration. The proteins involved in these processes are regulated in their biosynthesis by the cellular Cu ion status. The best studied bacterial Cu metalloregulation system is found in the gram-positive bacterium Enterococcus hirae. Cellular Cu levels in this bacterium control the expression of two P-type ATPases critical for Cu homeostasis (Odermatt and Solioz, 1995). The CopA ATPase functions in Cu ion uptake, whereas the CopB ATPase is a Cu(I) efflux pump (Solioz and Odermatt, 1995). The biosynthesis of both ATPases is regulated by a Cu-responsive transcription factor, CopY (Harrison et al., 2000). In low ambient Cu levels Cop Y represses transcription of the two ATPase genes. On exposure to Cu(I), CopY dissociates from promoter/operator sites on DNA with a for Cu of 20 jlM (Strausak and Solioz, 1997). Transcription of copA and copB proceeds after dissociation of CuCopY. The only other metal ions that induce CopY dissociation from DNA in vitro are Ag(I) and Cd(II), although the in vivo activation of copA and copB is specihc to Cu salts. The CuCopY complex is dimeric with two Cu(I) ions binding per monomer (C. T. Dameron, personal communication). The structural basis for the Cu-induced dissociation of CopY is unknown. Curiously, CopY is also activated in Cu-dehcient cells, but the mechanism is distinct from the described Cu-induced dissociation from DNA (Wunderh-Ye and Solioz, 1999). 

The primary organ for the regulation of sodium, potassium, calcium, and magnesium is the kidney. An intricate series of physiological sensing elements and hormonal response mechanisms maintains homeostasis. A variety of diuretic drugs can be used to enhance urinary output of various soluble salts, primarily sodium and potassium chloride. Profuse sweating is also a pathway of excretion for soluble salts and occasionally zinc. ... 

Aperia A, Broberger O, Thodenius K, Zetterstrom R. Development of renal control of salt and fluid homeostasis during the first year of life. Acta Pediatr Scand 1975 64 393-8. 

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