Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01185 (vasopressin)
 23,126 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The identification, characterization, and mutational analysis of three different genes, namely the prepro-arginine-vasopressin-neurophysin II gene (prepro-AVP-NPII), the arginine-vasopressin receptor 2 gene (AVPR2), and the vasopressin-sensitive water channel gene (aquaporin-2, AQP2), provide the basis for our understanding of three different hereditary forms of diabetes insipidus: autosomal dominant neurogenic diabetes insipidus, X-linked nephrogenic diabetes insipidus, and autosomal recessive nephrogenic diabetes insipidus, respectively. These advances provide diagnostic tools for physicians caring for these patients.
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PMID:Molecular biology of diabetes insipidus. 754 Nov 87

The effect of vasopressin on subcellular localization of AQP-CD and AQP3 water channels was examined in thirsted Brattleboro rats by immunohistochemistry and immunoelectron microscopy. AQP-CD was mainly present in the cytoplasm of the collecting duct cells in association with cytoplasmic vesicles but was sparse in the apical membrane in control vehicle-injected rats. In rats given vasopressin 15 min before death, the number of immunogold particles for AQP-CD in the apical membrane increased significantly (P < 0.002) from 1.8 +/- 0.2 to 10.0 +/- 0.4/microns with a significant decrease (P < 0.05) of cytoplasmic labeling from 32.6 +/- 6.4 to 24.6 +/- 5.6/microns 2, indicating that AQP-CD is the vasopressin-regulated water channel predicted by the "shuttle" hypothesis. In contrast, AQP3 was restricted to the basolateral membrane of the collecting duct cells, and the labeling density of AQP3 was unchanged by vasopressin treatment, indicating that AQP3 is constitutively expressed and may maintain high water permeability of the basolateral membrane.
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PMID:Vasopressin increases AQP-CD water channel in apical membrane of collecting duct cells in Brattleboro rats. 754 41

The cellular and subcellular localization and expression of a kidney collecting duct water channel, aquaporin (AQP)-CD, were examined in the kidneys of hydrated and dehydrated rats by immunostaining, Northern blot analysis, and radioimmunoassay. In hydrated rat kidneys, AQP-CD was selectively found in the collecting duct principal cells and inner medullary collecting duct cells, but not in the intercalated cells. At a light microscopic level, AQP-CD was diffusely present in a granular pattern throughout the cytoplasm of the collecting duct cells with a preferential accumulation in subapical regions. By immunoelectron microscopy, AQP-CD was frequently demonstrated along membranes of small vesicles in the subapical cytoplasm and occasionally along the basolateral membranes of these cells. However, immunolabeling was sparse on the apical membranes. In dehydrated rats, AQP-CD immunostaining was intensified in the subapical cytoplasm of the collecting duct cells, along with increases in the number and size of AQP-CD-bearing vesicles in the subapical regions and with increment of labeling along the apical membranes. The increase in the amount of AQP-CD in the collecting duct cells of dehydrated rat kidneys was quantitatively confirmed by elevation of AQP-CD at mRNA and protein levels. The AQP-CD localization is consistent with the predicted site of the antidiuretic hormone (ADH)-regulated water channel in the collecting ducts and the increase in AQP-CD at mRNA and protein levels by dehydration may account for high concentration of urine in dehydrated subjects.
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PMID:Localization and expression of a collecting duct water channel, aquaporin, in hydrated and dehydrated rats. 754 39

Circulating concentrations of oxytocin increase to 10-40 pM in rats in response to osmotic stimuli, suggesting that oxytocin could play a role in regulation of water balance. The present studies tested whether oxytocin at such concentrations increases osmotic water permeability (Pf) in isolated perfused terminal inner medullary collecting ducts (IMCD). In IMCD segments from Sprague-Dawley rats, 20 pM oxytocin added to the peritubular bath caused a two- to threefold increase in Pf, whereas 200 pM oxytocin increased Pf by five- to sixfold (n = 8, P < 0.01). IMCD from Brattleboro rats, which manifest central diabetes insipidus, exhibited a 2.8-fold increase in Pf in response to 20 pM oxytocin and a 4.7-fold increase in response to 200 pM oxytocin. However, in Brattleboro rats, the response to 20 pM oxytocin was dependent on prior water restriction of the rats. Immunoblotting showed no change in the expression of the aquaporin-CD water channel in Brattleboro rats in response to water restriction. Nevertheless, immunofluorescence studies of inner medullary tissue from Brattleboro rats revealed a marked redistribution of the aquaporin-CD water channels to a predominantly apical and subapical localization in IMCD cells in response to water restriction, similar to the redistribution seen in response to vasopressin. Mathematical modeling studies revealed that the measured increase in Pf in response to oxytocin is sufficient to generate a concentrated urine. We conclude that oxytocin can function physiologically as an antidiuretic hormone, mimicking the short-term action of vasopressin on water permeability, albeit with somewhat lower potency.
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PMID:Oxytocin as an antidiuretic hormone. I. Concentration dependence of action. 754 52

The aquaporins (AQPs) are a family of homologous water-channel proteins that can be inserted into epithelial cell plasma membranes either constitutively (AQP1) or by regulated exocytosis following vasopressin stimulation (AQP2). LLC-PK1 porcine renal epithelial cells were stably transfected with cDNA encoding AQP2 (tagged with a C-terminal c-Myc epitope) or rat kidney AQP1 cDNA in an expression vector containing a cytomegalovirus promoter. Immunofluorescence staining revealed that AQP1 was mainly localized to the plasma membrane, whereas AQP2 was predominantly located on intracellular vesicles. After treatment with vasopressin or forskolin for 10 min, AQP2 was relocated to the plasma membrane, indicating that this relocation was induced by cAMP. The location of AQP1 did not change. The basal water permeability of AQP1-transfected cells was 2-fold greater than that of nontransfected cells, whereas the permeability of AQP2-transfected cells increased significantly only after vasopressin treatment. Endocytotic uptake of fluorescein isothiocyanate-coupled dextran was stimulated 6-fold by vasopressin in AQP2-transfected cells but was only slightly increased in wild-type or AQP1-transfected cells. This vasopressin-induced endocytosis was inhibited in low-K+ medium, which selectively affects clathrin-mediated endocytosis. These water channel-transfected cells represent an in vitro system that will allow the detailed dissection of mechanisms involved in the processing, targeting, and trafficking of proteins via constitutive versus regulated intracellular transport pathways.
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PMID:Constitutive and regulated membrane expression of aquaporin 1 and aquaporin 2 water channels in stably transfected LLC-PK1 epithelial cells. 754 77

In the toad urinary bladder, antidiuretic hormone (ADH)-mediated changes in water permeability depend on exocytic insertion and endocytic retrieval of water channels into and from the apical membrane, respectively. Because GTP-binding proteins (G proteins) are well-recognized regulators of vesicular trafficking throughout the cell, we tested the hypothesis that drugs interfering with G protein would modify the hydrosmotic response to ADH and the ADH-regulated formation of endosomes, as assessed by luminal incorporation of a fluid-phase marker [fluorescein isothiocyanate (FITC)-dextran, 70 kDa]. Mastoparan (4 microM) and compound 48/80 (poly-p-methoxyphenylethylmethylamine; 50 micrograms/ml), added to the luminal side of the toad urinary bladder, as well as AlF3 added to the serosal side (400 microM), inhibited ADH- and 8-bromoadenosine 3',5'-cyclic monophosphate-induced transepithelial water flow by > 50% and simultaneously enhanced cellular incorporation of FITC-dextran by > 200%. The pattern of FITC-dextran uptake observed using fluorescence microscopy both in scraped cells and in the intact bladder was granular, suggesting fluid-phase endocytosis. Mastoparan and AlF3, which are both probes of G proteins, increased FITC-dextran uptake only in the presence of ADH and a transepithelial osmotic gradient, i.e., under conditions where water channel-carrying endosomes presumably cycle. Therefore, we suggest that the ADH-dependent cycling of water channels could be controlled by one or more G proteins associated with the apical membrane and/or the water channel-carrying vesicles.
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PMID:Drugs activating G proteins disturb cycling of ADH-dependent water channels in toad urinary bladder. 754 30

Aquaporin-2 (AQP2) is the predominant vasopressin-regulated water channel of the renal collecting duct. We tested whether vasopressin induces translocation of AQP2 from intracellular vesicles into the apical plasma membrane. AQP2 was quantitated in plasma membrane and intracellular vesicle fractions prepared from the inner medulla of one kidney from each rat before or 20 min after intravenous 1-desamino-8-D-arginine vasopressin (DDAVP) treatment, using immunoblotting and densitometry. Contralateral kidneys were prepared for immunofluorescence and immunoelectron microscopy. Immunoblotting revealed that, compared with untreated controls, DDAVP treatment significantly increased the fraction of AQP2 protein associated with the plasma membrane fraction relative to intracellular vesicles. This increase averaged 2.0-fold in untreated rats and 2.9-fold in rats water loaded for 12 h. Water loading, presumably by suppressing circulating vasopressin levels, decreased the fraction of AQP2 associated with the plasma membrane by 55%, suggesting retrieval of AQP2 from the plasma membrane. In rats sequentially thirsted for 48 h to increase expression and then water loaded for 72 h to minimize plasma membrane labeling, DDAVP caused a 12-fold increase in the plasma membrane to intracellular vesicle labeling ratio. The accentuation of the DDAVP response seen after water loading is consistent with the observed increase in the fraction of AQP2 in the intracellular pool available for insertion. Immunofluorescence confirmed a marked DDAVP-induced redistribution of AQP2 from intracellular to plasma membrane domains. Furthermore, quantitative immunoelectron microscopy demonstrated a 3.4-fold increase in apical plasma membrane to intracellular vesicle labeling ratio. These results provide a direct in vivo demonstration of vasopressin-induced translocation of AQP2 into the apical plasma membrane.
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PMID:Redistribution of aquaporin-2 water channels induced by vasopressin in rat kidney inner medullary collecting duct. 757 95

The advances in our understanding of the pathophysiology of defects in the antidiuretic hormone, the V2 receptor and the water channel, owing to mutations in the prepro-AVP-NPII, AVPR2 and AQP2 genes respectively, is providing insight into inherited diabetes insipidus as well as the more numerous sporadic cases. Further structure-function analyses of these mutated genes will increase our understanding of normal vasopressin-regulated water transport across the kidney epithelium at the molecular level.
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PMID:Diabetes insipidus. 757 30

In the vasopressin-stimulated inner medullary collecting duct (IMCD), urea is transported through a pathway which is distinct from a water channel. Therefore, no frictional interaction between urea and water should occur at the membrane level, and the reflection coefficient for urea must be close to unity. However, the presence of unstirred layers in the vicinity of membranes causes solute concentration polarization, leading to an underestimation of the reflection coefficient (apparent reflection coefficient). When the value is determined across the perfused renal tubular wall, the intracellular space also constitutes an unstirred layer. The profile of solute and water transport across the system consisting of two membranes and the interposed intracellular space was simulated by a computer to examine the effect of unstirred layer on the value of apparent reflection coefficient. The model demonstrated that the imposed osmotic gradient across the tubular epithelial is decreased at each membrane interface. Under conditions of minimal unstirred layers in the bathing fluid, the existence of the intracellular constraints to diffusion cause considerable underestimation of the reflection coefficient. The higher the membrane permeability of urea and the smaller the diffusion coefficient of urea in the intracellular space, the greater becomes the magnitude of the underestimation. Thus, the measured apparent reflection coefficient for urea may become significantly less than the estimated value, leading to a reduction of the effective transmural osmotic driving force.
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PMID:Effect of intracellular unstirred layer on apparent reflection coefficient for urea in inner medullary collecting duct: a computer simulation. 762 Aug 57

Congenital nephrogenic diabetes insipidus (NDI) is a rare inherited disorder characterized by the inability of the kidney to concentrate urine in response to vasopressin (AVP). Following the recent characterization of the cDNA and genomics sequences encoding the human V2 receptor to AVP (AVPR2), X-linked NDI has been found to be due to mutations in the AVPR2 gene that maps to the chromosome Xq28 region. To date more than 30 mutations, insertions or deletions have been reported in independent families, without any significant differences in the phenotypic expression of the disease. The AVPR2 is a member of the superfamily of 7 transmembrane domain, G protein-coupled receptor, linked to cyclic AMP second messenger system. Other types of inheritance have been described in NDI, and recently, a mutation of the aquaporin-2 gene, encoding a water channel of the renal collecting duct, has been reported in an autosomal recessive form of NDI.
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PMID:[Hereditary nephrogenic diabetes insipidus]. 764 Jul 59


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