Aquaporin 1: Aquaporin 1 forms a water-specific channel that is constitutively expressed at the PLASMA MEMBRANE of ERYTHROCYTES and KIDNEY TUBULES, PROXIMAL. It provides these cells with a high permeability to WATER. In humans polymorphisms of this protein result in the Colton blood group antigen.Aquaporin 5: Aquaporin 5 is a water-specific channel protein that is expressed primarily in alveolar, tracheal, and upper bronchial EPITHELIUM. It plays an important role in maintaining water HOMEOSTASIS in the LUNGS and may also regulate release of SALIVA and TEARS in the SALIVARY GLANDS and the LACRIMAL GLAND.Aquaporin 3: Aquaporin 3 is an aquaglyceroporin that is expressed in the KIDNEY COLLECTING DUCTS and is constitutively localized at the basolateral MEMBRANE.Aquaporin 4: Aquaporin 4 is the major water-selective channel in the CENTRAL NERVOUS SYSTEM of mammals.Aquaporins: A class of porins that allow the passage of WATER and other small molecules across CELL MEMBRANES.Aquaporin 2: Aquaporin 2 is a water-specific channel protein that is expressed in KIDNEY COLLECTING DUCTS. The translocation of aquaporin 2 to the apical PLASMA MEMBRANE is regulated by VASOPRESSIN, and MUTATIONS in AQP2 have been implicated in a variety of kidney disorders including DIABETES INSIPIDUS.Aquaporin 6: Aquaporin 6 is an aquaglyceroporin that is found primarily in KIDNEY COLLECTING DUCTS. AQP6 protein functions as an anion-selective channel.Water: A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Mercuric Chloride: Mercury chloride (HgCl2). A highly toxic compound that volatizes slightly at ordinary temperature and appreciably at 100 degrees C. It is corrosive to mucous membranes and used as a topical antiseptic and disinfectant.Osmosis: Tendency of fluids (e.g., water) to move from the less concentrated to the more concentrated side of a semipermeable membrane.Aquaglyceroporins: A subgroup of aquaporins that transport WATER; GLYCEROL; and other small solutes across CELL MEMBRANES.Blood Group Antigens: Sets of cell surface antigens located on BLOOD CELLS. They are usually membrane GLYCOPROTEINS or GLYCOLIPIDS that are antigenically distinguished by their carbohydrate moieties.Water-Electrolyte Balance: The balance of fluid in the BODY FLUID COMPARTMENTS; total BODY WATER; BLOOD VOLUME; EXTRACELLULAR SPACE; INTRACELLULAR SPACE, maintained by processes in the body that regulate the intake and excretion of WATER and ELECTROLYTES, particularly SODIUM and POTASSIUM.Glycerol: A trihydroxy sugar alcohol that is an intermediate in carbohydrate and lipid metabolism. It is used as a solvent, emollient, pharmaceutical agent, and sweetening agent.Permeability: Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.Cell Membrane Permeability: A quality of cell membranes which permits the passage of solvents and solutes into and out of cells.Plant Transpiration: The loss of water vapor by plants to the atmosphere. It occurs mainly from the leaves through pores (stomata) whose primary function is gas exchange. The water is replaced by a continuous column of water moving upwards from the roots within the xylem vessels. (Concise Dictionary of Biology, 1990)Kidney Tubules, Collecting: Straight tubes commencing in the radiate part of the kidney cortex where they receive the curved ends of the distal convoluted tubules. In the medulla the collecting tubules of each pyramid converge to join a central tube (duct of Bellini) which opens on the summit of the papilla.Kidney Concentrating Ability: The ability of the kidney to excrete in the urine high concentrations of solutes from the blood plasma.Diabetes Insipidus, Nephrogenic: A genetic or acquired polyuric disorder characterized by persistent hypotonic urine and HYPOKALEMIA. This condition is due to renal tubular insensitivity to VASOPRESSIN and failure to reduce urine volume. It may be the result of mutations of genes encoding VASOPRESSIN RECEPTORS or AQUAPORIN-2; KIDNEY DISEASES; adverse drug effects; or complications from PREGNANCY.Plant Proteins: Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.Ion Channels: Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.Neuromyelitis Optica: A syndrome characterized by acute OPTIC NEURITIS; MYELITIS, TRANSVERSE; demyelinating and/or necrotizing lesions in the OPTIC NERVES and SPINAL CORD; and presence of specific autoantibodies to AQUAPORIN 4.Polyuria: Urination of a large volume of urine with an increase in urinary frequency, commonly seen in diabetes (DIABETES MELLITUS; DIABETES INSIPIDUS).Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.Xenopus laevis: The commonest and widest ranging species of the clawed "frog" (Xenopus) in Africa. This species is used extensively in research. There is now a significant population in California derived from escaped laboratory animals.Osmotic Pressure: The pressure required to prevent the passage of solvent through a semipermeable membrane that separates a pure solvent from a solution of the solvent and solute or that separates different concentrations of a solution. It is proportional to the osmolality of the solution.Oocytes: Female germ cells derived from OOGONIA and termed OOCYTES when they enter MEIOSIS. The primary oocytes begin meiosis but are arrested at the diplotene state until OVULATION at PUBERTY to give rise to haploid secondary oocytes or ova (OVUM).Antidiuretic Agents: Agents that reduce the excretion of URINE, most notably the octapeptide VASOPRESSINS.Molecular Sequence Data: Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.Tulipa: A plant genus of the family LILIACEAE. Members contain tuliposides and tulipalins and have been associated with allergic contact dermatitis in florists.Vapor Pressure: The contribution to barometric PRESSURE of gaseous substance in equilibrium with its solid or liquid phase.Amino Acid Sequence: The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.Cistaceae: A plant family of the order Violales, subclass Dilleniidae, class Magnoliopsida. The common name of rock rose is used with several plants of this family.Plant Roots: The usually underground portions of a plant that serve as support, store food, and through which water and mineral nutrients enter the plant. (From American Heritage Dictionary, 1982; Concise Dictionary of Biology, 1990)Brain Edema: Increased intracellular or extracellular fluid in brain tissue. Cytotoxic brain edema (swelling due to increased intracellular fluid) is indicative of a disturbance in cell metabolism, and is commonly associated with hypoxic or ischemic injuries (see HYPOXIA, BRAIN). An increase in extracellular fluid may be caused by increased brain capillary permeability (vasogenic edema), an osmotic gradient, local blockages in interstitial fluid pathways, or by obstruction of CSF flow (e.g., obstructive HYDROCEPHALUS). (From Childs Nerv Syst 1992 Sep; 8(6):301-6)Mercury Compounds: Inorganic compounds that contain mercury as an integral part of the molecule.Cell Membrane: The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.Membrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.Lens, Crystalline: A transparent, biconvex structure of the EYE, enclosed in a capsule and situated behind the IRIS and in front of the vitreous humor (VITREOUS BODY). It is slightly overlapped at its margin by the ciliary processes. Adaptation by the CILIARY BODY is crucial for OCULAR ACCOMMODATION.Gene Expression Regulation, Plant: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in plants.Eye ProteinsBody Water: Fluids composed mainly of water found within the body.Renal Agents: Drugs used for their effects on the kidneys' regulation of body fluid composition and volume. The most commonly used are the diuretics. Also included are drugs used for their antidiuretic and uricosuric actions, for their effects on the kidneys' clearance of other drugs, and for diagnosis of renal function.AnguillaOsmolar Concentration: The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.Vasopressins: Antidiuretic hormones released by the NEUROHYPOPHYSIS of all vertebrates (structure varies with species) to regulate water balance and OSMOLARITY. In general, vasopressin is a nonapeptide consisting of a six-amino-acid ring with a cysteine 1 to cysteine 6 disulfide bridge or an octapeptide containing a CYSTINE. All mammals have arginine vasopressin except the pig with a lysine at position 8. Vasopressin, a vasoconstrictor, acts on the KIDNEY COLLECTING DUCTS to increase water reabsorption, increase blood volume and blood pressure.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.Dehydration: The condition that results from excessive loss of water from a living organism.RNA, Messenger: RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.Glomeromycota: A phylum of fungi that are mutualistic symbionts and form ARBUSCULAR MYCORRHIZAE with PLANT ROOTS.Microscopy, Electron, Scanning Transmission: A type of TRANSMISSION ELECTRON MICROSCOPY in which the object is examined directly by an extremely narrow electron beam scanning the specimen point-by-point and using the reactions of the electrons that are transmitted through the specimen to create the image. It should not be confused with SCANNING ELECTRON MICROSCOPY.Salivary Glands: Glands that secrete SALIVA in the MOUTH. There are three pairs of salivary glands (PAROTID GLAND; SUBLINGUAL GLAND; SUBMANDIBULAR GLAND).Mycelium: The body of a fungus which is made up of HYPHAE.Deamino Arginine Vasopressin: A synthetic analog of the pituitary hormone, ARGININE VASOPRESSIN. Its action is mediated by the VASOPRESSIN receptor V2. It has prolonged antidiuretic activity, but little pressor effects. It also modulates levels of circulating FACTOR VIII and VON WILLEBRAND FACTOR.Propylene Glycol: A clear, colorless, viscous organic solvent and diluent used in pharmaceutical preparations.Mesophyll Cells: Large and highly vacuolated cells possessing many chloroplasts occuring in the interior cross-section of leaves, juxtaposed between the epidermal layers.Mesembryanthemum: A plant genus of the family AIZOACEAE. It is a native of Africa and widely planted for erosion control to stabilize soil along roadsides and beaches.Kidney Medulla: The internal portion of the kidney, consisting of striated conical masses, the renal pyramids, whose bases are adjacent to the cortex and whose apices form prominent papillae projecting into the lumen of the minor calyces.Kidney: Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.Submandibular Gland: One of two salivary glands in the neck, located in the space bound by the two bellies of the digastric muscle and the angle of the mandible. It discharges through the submandibular duct. The secretory units are predominantly serous although a few mucous alveoli, some with serous demilunes, occur. (Stedman, 25th ed)Receptors, Vasopressin: Specific molecular sites or proteins on or in cells to which VASOPRESSINS bind or interact in order to modify the function of the cells. Two types of vasopressin receptor exist, the V1 receptor in the vascular smooth muscle and the V2 receptor in the kidneys. The V1 receptor can be subdivided into V1a and V1b (formerly V3) receptors.Droughts: Prolonged dry periods in natural climate cycle. They are slow-onset phenomena caused by rainfall deficit combined with other predisposing factors.Astrocytes: A class of large neuroglial (macroglial) cells in the central nervous system - the largest and most numerous neuroglial cells in the brain and spinal cord. Astrocytes (from "star" cells) are irregularly shaped with many long processes, including those with "end feet" which form the glial (limiting) membrane and directly and indirectly contribute to the BLOOD-BRAIN BARRIER. They regulate the extracellular ionic and chemical environment, and "reactive astrocytes" (along with MICROGLIA) respond to injury.Reverse Transcriptase Polymerase Chain Reaction: A variation of the PCR technique in which cDNA is made from RNA via reverse transcription. The resultant cDNA is then amplified using standard PCR protocols.Xenopus: An aquatic genus of the family, Pipidae, occurring in Africa and distinguished by having black horny claws on three inner hind toes.Mercury: A silver metallic element that exists as a liquid at room temperature. It has the atomic symbol Hg (from hydrargyrum, liquid silver), atomic number 80, and atomic weight 200.59. Mercury is used in many industrial applications and its salts have been employed therapeutically as purgatives, antisyphilitics, disinfectants, and astringents. It can be absorbed through the skin and mucous membranes which leads to MERCURY POISONING. Because of its toxicity, the clinical use of mercury and mercurials is diminishing.Gene Expression: The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.Nobel PrizeRats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Spinacia oleracea: A widely cultivated plant, native to Asia, having succulent, edible leaves eaten as a vegetable. (From American Heritage Dictionary, 1982)Glycerol Kinase: An enzyme that catalyzes the formation of glycerol 3-phosphate from ATP and glycerol. Dihydroxyacetone and L-glyceraldehyde can also act as acceptors; UTP and, in the case of the yeast enzyme, ITP and GTP can act as donors. It provides a way for glycerol derived from fats or glycerides to enter the glycolytic pathway. EC Transport: The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport.Pichia: Yeast-like ascomycetous fungi of the family Saccharomycetaceae, order SACCHAROMYCETALES isolated from exuded tree sap.Fragaria: A plant genus of the family ROSACEAE known for the edible fruit.Rats, Brattleboro: A mutant strain of Rattus norvegicus used in research on renal function and hypertension and as a disease model for diabetes insipidus.Plant Stomata: Closable openings in the epidermis of plants on the underside of leaves. They allow the exchange of gases between the internal tissues of the plant and the outside atmosphere.Proteolipids: Protein-lipid combinations abundant in brain tissue, but also present in a wide variety of animal and plant tissues. In contrast to lipoproteins, they are insoluble in water, but soluble in a chloroform-methanol mixture. The protein moiety has a high content of hydrophobic amino acids. The associated lipids consist of a mixture of GLYCEROPHOSPHATES; CEREBROSIDES; and SULFOGLYCOSPHINGOLIPIDS; while lipoproteins contain PHOSPHOLIPIDS; CHOLESTEROL; and TRIGLYCERIDES.Blotting, Western: Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.Saline Solution, Hypertonic: Hypertonic sodium chloride solution. A solution having an osmotic pressure greater than that of physiologic salt solution (0.9 g NaCl in 100 ml purified water).Antimony Potassium Tartrate: A schistosomicide possibly useful against other parasites. It has irritant emetic properties and may cause lethal cardiac toxicity among other adverse effects.Plant Leaves: Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Malpighian Tubules: Slender tubular or hairlike excretory structures found in insects. They emerge from the alimentary canal between the mesenteron (midgut) and the proctodeum (hindgut).Glial Fibrillary Acidic Protein: An intermediate filament protein found only in glial cells or cells of glial origin. MW 51,000.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.RNA, Complementary: Synthetic transcripts of a specific DNA molecule or fragment, made by an in vitro transcription system. This cRNA can be labeled with radioactive uracil and then used as a probe. (King & Stansfield, A Dictionary of Genetics, 4th ed)Immunoblotting: Immunologic method used for detecting or quantifying immunoreactive substances. The substance is identified by first immobilizing it by blotting onto a membrane and then tagging it with labeled antibodies.PhloretinMicroscopy, Immunoelectron: Microscopy in which the samples are first stained immunocytochemically and then examined using an electron microscope. Immunoelectron microscopy is used extensively in diagnostic virology as part of very sensitive immunoassays.Models, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Freezing: Liquids transforming into solids by the removal of heat.Solute Carrier Family 12, Member 1: Na-K-Cl transporter in the ASCENDING LIMB OF LOOP OF HENLE. It mediates active reabsorption of sodium chloride and is inhibited by LOOP DIURETICS such as FUROSEMIDE; and BUMETANIDE. Mutations in the gene encoding SLC12A1 are associated with a BARTTER SYNDROME.4-Chloromercuribenzenesulfonate: A cytotoxic sulfhydryl reagent that inhibits several subcellular metabolic systems and is used as a tool in cellular physiology.Mice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.DNA Primers: Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.Urea: A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.Hypertonic Solutions: Solutions that have a greater osmotic pressure than a reference solution such as blood, plasma, or interstitial fluid.Arabidopsis: A plant genus of the family BRASSICACEAE that contains ARABIDOPSIS PROTEINS and MADS DOMAIN PROTEINS. The species A. thaliana is used for experiments in classical plant genetics as well as molecular genetic studies in plant physiology, biochemistry, and development.Gene Expression Regulation: Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation.Cell Size: The quantity of volume or surface area of CELLS.Morula: An early embryo that is a compact mass of about 16 BLASTOMERES. It resembles a cluster of mulberries with two types of cells, outer cells and inner cells. Morula is the stage before BLASTULA in non-mammalian animals or a BLASTOCYST in mammals.Sodium-Potassium-Chloride Symporters: A subclass of symporters that specifically transport SODIUM CHLORIDE and/or POTASSIUM CHLORIDE across cellular membranes in a tightly coupled process.DNA, Complementary: Single-stranded complementary DNA synthesized from an RNA template by the action of RNA-dependent DNA polymerase. cDNA (i.e., complementary DNA, not circular DNA, not C-DNA) is used in a variety of molecular cloning experiments as well as serving as a specific hybridization probe.Epithelial Cells: Cells that line the inner and outer surfaces of the body by forming cellular layers (EPITHELIUM) or masses. Epithelial cells lining the SKIN; the MOUTH; the NOSE; and the ANAL CANAL derive from ectoderm; those lining the RESPIRATORY SYSTEM and the DIGESTIVE SYSTEM derive from endoderm; others (CARDIOVASCULAR SYSTEM and LYMPHATIC SYSTEM) derive from mesoderm. Epithelial cells can be classified mainly by cell shape and function into squamous, glandular and transitional epithelial cells.Quercus: A plant genus of the family FAGACEAE that is a source of TANNINS. Do not confuse with Holly (ILEX).Cloning, Molecular: The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.Protein Conformation: The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).Zea mays: A plant species of the family POACEAE. It is a tall grass grown for its EDIBLE GRAIN, corn, used as food and animal FODDER.Molecular Dynamics Simulation: A computer simulation developed to study the motion of molecules over a period of time.Acclimatization: Adaptation to a new environment or to a change in the old.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Hydroxyethyl Starch Derivatives: Starches that have been chemically modified so that a percentage of OH groups are substituted with 2-hydroxyethyl ether groups.Sodium Chloride: A ubiquitous sodium salt that is commonly used to season food.

Lung fluid transport in aquaporin-1 and aquaporin-4 knockout mice. (1/452)

The mammalian lung expresses water channel aquaporin-1 (AQP1) in microvascular endothelia and aquaporin-4 (AQP4) in airway epithelia. To test whether these water channels facilitate fluid movement between airspace, interstitial, and capillary compartments, we measured passive and active fluid transport in AQP1 and AQP4 knockout mice. Airspace-capillary osmotic water permeability (Pf) was measured in isolated perfused lungs by a pleural surface fluorescence method. Pf was remarkably reduced in AQP1 (-/-) mice (measured in cm/s x 0.001, SE, n = 5-10: 17 +/- 2 [+/+]; 6.6 +/- 0.6 AQP1 [+/-]; 1.7 +/- 0.3 AQP1 [-/-]; 12 +/- 1 AQP4 [-/-]). Microvascular endothelial water permeability, measured by a related pleural surface fluorescence method in which the airspace was filled with inert perfluorocarbon, was reduced more than 10-fold in AQP1 (-/-) vs. (+/+) mice. Hydrostatically induced lung interstitial and alveolar edema was measured by a gravimetric method and by direct measurement of extravascular lung water. Both approaches indicated a more than twofold reduction in lung water accumulation in AQP1 (-/-) vs. (+/+) mice in response to a 5- to 10-cm H2O increase in pulmonary artery pressure for five minutes. Active, near-isosmolar alveolar fluid absorption (Jv) was measured in in situ perfused lungs using 125I-albumin as an airspace fluid volume marker. Jv (measured in percent fluid uptake at 30 min, n = 5) in (+/+) mice was 6.0 +/- 0.6 (37 degrees C), increased to 16 +/- 1 by beta-agonists, and inhibited to less than 2.0 by amiloride, ouabain, or cooling to 23 degrees C. Jv (with isoproterenol) was not affected by aquaporin deletion (18.9 +/- 2.2 [+/+]; 16.4 +/- 1.5 AQP1 [-/-]; 16.3 +/- 1.7 AQP4 [-/-]). These results indicate that osmotically driven water transport across microvessels in adult lung occurs by a transcellular route through AQP1 water channels and that the microvascular endothelium is a significant barrier for airspace-capillary osmotic water transport. AQP1 facilitates hydrostatically driven lung edema but is not required for active near-isosmolar absorption of alveolar fluid.  (+info)

Expression and localization of aquaporins in rat gastrointestinal tract. (2/452)

A family of water-selective channels, aquaporins (AQP), has been demonstrated in various organs and tissues. However, the localization and expression of the AQP family members in the gastrointestinal tract have not been entirely elucidated. This study aimed to demonstrate the expression and distribution of several types of the AQP family and to speculate on their role in water transport in the rat gastrointestinal tract. By RNase protection assay, expression of AQP1-5 and AQP8 was examined in various portions through the gastrointestinal tract. AQP1 and AQP3 mRNAs were diffusely expressed from esophagus to colon, and their expression was relatively intense in the small intestine and colon. In contrast, AQP4 mRNA was selectively expressed in the stomach and small intestine and AQP8 mRNA in the jejunum and colon. Immunohistochemistry and in situ hybridization demonstrated cellular localization of these AQP in these portions. AQP1 was localized on endothelial cells of lymphatic vessels in the submucosa and lamina propria throughout the gastrointestinal tract. AQP3 was detected on the circumferential plasma membranes of stratified squamous epithelial cells in the esophagus and basolateral membranes of cardiac gland epithelia in the lower stomach and of surface columnar epithelia in the colon. However, AQP3 was not apparently detected in the small intestine. AQP4 was present on the basolateral membrane of the parietal cells in the lower stomach and selectively in the basolateral membranes of deep intestinal gland cells in the small intestine. AQP8 mRNA expression was demonstrated in the absorptive columnar epithelial cells of the jejunum and colon by in situ hybridization. These findings may indicate that water crosses the epithelial layer through these water channels, suggesting a possible role of the transcellular route for water intake or outlet in the gastrointestinal tract.  (+info)

Na/K-ATPase in intercalated cells along the rat nephron revealed by antigen retrieval. (3/452)

The Na/K-ATPase plays a fundamental role in the physiology of various mammalian cells. In the kidney, previous immunocytochemical studies have localized this protein to the basolateral membrane in different tubule segments. However, intercalated cells (IC) of the collecting duct (CD) in rat and mouse were unlabeled with anti-Na/K-ATPase antibodies. An antigen retrieval technique has been recently described in which tissue sections are pretreated with sodium dodecyl sulfate before immunostaining. This procedure was used to reexamine the presence of Na/K-ATPase in IC along the rat nephron using monoclonal antibodies against the Na/K-ATPase alpha-subunit. Subtypes of IC along the nephron were identified by their distinctive staining with polyclonal and monoclonal antibodies to the 31-kD vacuolar H+ -ATPase subunit, whereas principal cells (PC) were labeled with a polyclonal antibody to the water channel aquaporin-4 (AQP-4). In PC, the Na/K-ATPase and AQP-4 staining colocalized basolaterally. In contrast to previous reports, we found that IC of all types showed basolateral labeling with the anti-Na/K-ATPase antibody. The staining was quantified by fluorescence image analysis. It was weak to moderate in IC of cortical and outer medullary collecting ducts and most intense in IC of the initial inner medullary collecting duct. IC in the initial inner medulla showed a staining intensity that was equivalent or stronger to that in adjacent principal cells. Models of ion transport at the cellular and epithelial level in rat kidney, therefore, must take into account the potential role of a basolateral Na/K-ATPase in intercalated cell function.  (+info)

Renal expression of aquaporins in liver cirrhosis induced by chronic common bile duct ligation in rats. (4/452)

Semiquantitative immunoblotting was used to investigate the expression levels of the four major renal aquaporins, the Na-K-2Cl cotransporter of the thick ascending limb, the type 3 Na-H exchanger, and the Na-K-ATPase in kidneys from rats with cirrhosis secondary to common bile duct ligation (CBDL). These rats had significant water retention and hyponatremia. In contrast to models of cirrhosis induced by carbon tetrachloride, aquaporin-2 expression in CBDL-induced cirrhosis was decreased. Thus, these results show that in the setting of extracellular fluid volume expansion, excessive water retention with hyponatremia can occur in the absence of increases in aquaporin-2 abundance. In addition, the expression levels of the two basolateral collecting duct aquaporins (aquaporin-3 and -4) were decreased in CBDL rats relative to sham-operated control rats. Similarly, the Na-K-2Cl cotransporter of the thick ascending limb and the type 3 Na-H exchanger showed decreases in expression. In contrast, the expression levels of aquaporin-1 and the all subunit of the Na-K-ATPase were not decreased. Thus, dysregulation of multiple water channels and ion transporters may play a role in water balance abnormalities associated with CBDL-induced cirrhosis in rats.  (+info)

High-resolution immunogold cytochemistry indicates that AQP4 is concentrated along the basal membrane of parietal cell in rat stomach. (5/452)

Gastric parietal cells secrete hydrochloric acid in stomach. Because the secreted HCl solution is isotonic with the plasma fluid, it should accompany the water transport across the membranes of parietal cells. Aquaporins (AQPs) are water channel proteins that play the central role in the cellular handling of water in various mammalian tissues. Using immunocytochemistry, we found that AQP4 was expressed only in parietal cells of rat gastric mucosa. Immunogold electron microscopy study further demonstrated that AQP4 was mostly localized at the basal membrane of parietal cells. In the basal membrane, AQP4 was prominently enriched on the portion contacting with the basement membrane surrounding gastric glands. These results suggest that the contact between basement membrane and basal membrane may generate the signal involved in the targeting of AQP4 in gastric parietal cells.  (+info)

Role of aquaporin-4 in airspace-to-capillary water permeability in intact mouse lung measured by a novel gravimetric method. (6/452)

The mammalian peripheral lung contains at least three aquaporin (AQP) water channels: AQP1 in microvascular endothelia, AQP4 in airway epithelia, and AQP5 in alveolar epithelia. In this study, we determined the role of AQP4 in airspace-to-capillary water transport by comparing water permeability in wild-type mice and transgenic null mice lacking AQP1, AQP4, or AQP1/AQP4 together. An apparatus was constructed to measure lung weight continuously during pulmonary artery perfusion of isolated mouse lungs. Osmotically induced water flux (J(v)) between the airspace and capillary compartments was measured from the kinetics of lung weight change in saline-filled lungs in response to changes in perfusate osmolality. J(v) in wild-type mice varied linearly with osmotic gradient size (4.4 x 10(-5) cm(3) s(-1) mOsm(-1)) and was symmetric, independent of perfusate osmolyte size, weakly temperature dependent, and decreased 11-fold by AQP1 deletion. Transcapillary osmotic water permeability was greatly reduced by AQP1 deletion, as measured by the same method except that the airspace saline was replaced by an inert perfluorocarbon. Hydrostatically induced lung edema was characterized by lung weight changes in response to changes in pulmonary arterial inflow or pulmonary venous outflow pressure. At 5 cm H(2)O outflow pressure, the filtration coefficient was 4.7 cm(3) s(-1) mOsm(-1) and reduced 1.4-fold by AQP1 deletion. To study the role of AQP4 in lung water transport, AQP1/AQP4 double knockout mice were generated by crossbreeding of AQP1 and AQP4 null mice. J(v) were (cm(3) s(-1) mOsm(-1) x 10(-5), SEM, n = 7-12 mice): 3.8 +/- 0. 4 (wild type), 0.35 +/- 0.02 (AQP1 null), 3.7 +/- 0.4 (AQP4 null), and 0.25 +/- 0.01 (AQP1/AQP4 null). The significant reduction in P(f) in AQP1 vs. AQP1/AQP4 null mice was confirmed by an independent pleural surface fluorescence method showing a 1.6 +/- 0.2-fold (SEM, five mice) reduced P(f) in the AQP1/AQP4 double knockout mice vs. AQP1 null mice. These results establish a simple gravimetric method to quantify osmosis and filtration in intact mouse lung and provide direct evidence for a contribution of the distal airways to airspace-to-capillary water transport.  (+info)

Aquaporin-4 is expressed in basolateral membranes of proximal tubule S3 segments in mouse kidney. (7/452)

Because of the availability of knockout mouse models to examine renal transport mechanisms, it has become increasingly important to describe the cellular distribution of major renal transporters in mice. We have used immunocytochemistry and freeze-fracture electron microscopy to compare the renal distribution of aquaporin-4 (AQP4) with that previously described in rat. In rat kidney AQP4 is present exclusively in basolateral membranes of collecting duct principal cells. In mice, however, AQP4 was also detected by immunocytochemistry in basolateral membranes of proximal tubule S3 segments, and not detected in S1 and S2 segments of proximal tubule. Freeze-fracture electron microscopy revealed orthogonal arrays of intramembrane particles (OAPs) on the basolateral membranes of the S3 segment. In AQP4-knockout mice, immunostaining was absent and OAPs were found neither in collecting ducts nor in the S3 segment of the proximal tubule. The urinary concentrating capacity after deletion of both AQP1 and AQP4 was further reduced compared with that of AQP1 or AQP4 null mice, suggesting an additive effect of AQP1 and AQP4 in the concentrating mechanism. The functional significance of the apparent species-dependent expression of AQP4 in proximal tubules is unknown, but may relate to physiological differences between rats and mice.  (+info)

Molecular cloning of two bovine aquaporin-4 cDNA isoforms and their expression in brain endothelial cells. (8/452)

Two cDNA isoforms of bovine aquaporin-4 (bAQP4-A and bAQP4-B) were newly isolated. Sequence analysis of both cDNAs revealed open reading frames of 972 (bAQP4-A) and 906 nucleotides (bAQP4-B) with deduced proteins of 323 (bAQP4-A) and 301 amino acid residues (bAQP4-B). Partial 5'-genomic sequence analysis showed that the 5'-noncoding sequences specific to bAQP4-A and -B transcripts were contained in distinct exons, exon 0 for bAQP4-A and new exon X for bAQP4-B. RNase protection assay demonstrated the definite expression of both isoforms in bovine brain. The deduced amino acid sequence of bAQP4-A was highly homologous to the human (97%), rat (95%), and mouse (93%) AQP4. Reverse transcription-PCR detected the expression of AQP4 mRNAs in bovine brain endothelial cells as well as in a variety of bovine organs such as brain, lung, spleen, and kidney. Northern blot analysis indicated that a 6.0 kb message is predominantly expressed in bovine brain and lung.  (+info)

  • The aquaporins (AQPs) are a family of water-transporting channels that are expressed widely in mammalian fluid-transporting epithelia and endothelia. (
  • 1 2 3 4 5 6 Because of this expression pattern, it has been proposed that AQPs play a role in intraocular pressure regulation, corneal and lens transparency, and vision. (
  • Aquaporins (AQPs) play fundamental roles in water and osmolyte homeostasis by facilitating water and small solute movement across plasma membranes of epithelial, endothelial, and other tissues. (
  • Aquaporins (AQPs) are integral membrane proteins engaged in the modulation of water homeostasis, but the roles they play in chronic otitis media (COM) have not been well investigated. (
  • We computationally determined the diffusional (PD) and osmotic (Pf) water permeability coefficients for the mammalian CDE based on in silico simulations of cochlear water dynamics integrating previously derived in vivo experimental data on fluid flow with expression sites of molecular water channels (aquaporins, AQPs). (
  • Aquaporins (AQPs) are water transporting proteins expressed widely in mammalian tissues including the eye. (
  • BACKGROUND: Hydrocephalus occurs because of an imbalance of bulk fluid flow in the brain, and aquaporins (AQPs) play pivotal roles in cerebral water movement as essential mediators during edema and fluid accumulation. (
  • METHODS: We evaluated differential expression of AQPs 1 and 4 in the congenital hydrocephalus Texas rat at postnatal days 5, 10, and 26 in isolated CP and cortex by enzyme-linked immunosorbent assay, Western blot, quantitative reverse transcriptase polymerase chain reaction, and immunohistochemistry. (
  • CONCLUSION: Biphasic AQP1 expression in the CP with increased AQPs 1 and 4 at the brain-fluid interfaces may indicate compensatory mechanisms to regulate choroidal cerebrospinal fluid secretion and increase parenchymal fluid absorption in the high-pressure hydrocephalic condition. (
  • Aquaporins (AQPs) play a physiological role in several organs and tissues, and their alteration is associated with disorders of water regulation. (
  • LS-F13079 is a 96-well enzyme-linked immunosorbent assay (ELISA) for the Quantitative detection of Human AQP4 / Aquaporin 4 in samples of Plasma and Serum. (
  • Should the Human Protease Activated Receptor 4 (PAR4) ELISA Kit is proven to show malperformance, you will receive a refund or a free replacement. (
  • Description: A sandwich quantitative ELISA assay kit for detection of Human Protease Activated Receptor 4 (PAR4) in samples from tissue homogenates, cell lysates or other biological fluids. (
  • Known also as Protease Activated Receptor 4 elisa. (
  • Prior indirect evidence has suggested the involvement of astrocyte water channel aquaporin-4 (AQP4) in the pathogenesis of TBI. (
  • Mechanisms proffered to explain astrocyte swelling emphasize the importance of either aquaporin-4 (Aqp4), an astrocyte water channel, or of Na+ channels and pumps, which mediate cellular osmolyte influx. (
  • Aquaporin-4 (AQP4) is implicated in a number of physiopathological processes, particularly in the development of brain edema, and other functions such as the regulation of extracellular space volume, potassium buffering, waste clearance, and calcium signaling. (
  • To our knowledge, no compounds that effectively block water permeability through aquaporin-4 have been discovered.My hypothesis is that an aquaporin-4 blocker would significantly decrease the cerebral edema formation after ischemic stroke in mice. (
  • I also proposed that dystrophin deficient mice, a mouse strain that has a decreased expression of aquaporin-4 channels would have a decrease formation of cerebral edema after transient ischemic stroke when compared with a strain matched controls.I found that bumetanide, a well-described Na+, K+, Cl- cotransporter inhibitor, reversibly and dose dependently inhibited water permeability through aquaporin-4 channels. (
  • We investigated clinical outcomes and prognostic characteristics of 106 aquaporin-4 antibody-seropositive patients from the UK and Japan. (
  • Thus, age at disease onset and genetic factors are both likely to be important in determining clinical outcomes in aquaporin-4 disease. (
  • Crucially, the diagnostic and therapeutic implications of aquaporin-4 IgG can only be ascertained with evidence from rigorous prospective clinical study in different immunogenetic populations, and further pathological investigations are necessary. (
  • Specifically, it shows reductions in AQP 4 and 6 mRNA levels, as observed in the otorrhea group, have an effect on the clinical manifestations of COM. (
  • In addition, V.A. Lennon is a named inventor on 2 patent applications filed by Mayo Foundation for Medical Education and Research relating to functional assays for detecting aquaporin-4 IgG and applications to cancer. (
  • Detection and analysis of Aquaporin-4 - specific effector/memory T cells in PBMCs by MACS ® Cytokine Secretion Assays, intracellular cytokine staining, or other technologies. (
  • 1. Waters P, McKeon A, Leite MI, et al: Multicenter comparison of aquaporin-4 IgG assays in NMO spectrum disorders. (
  • HEK293 cells were used as antigenic substrate after transfected with full-length human AQP4 and mocktransfected cells were used as control substrate [ 4 ]. (
  • Because of its importance for normal water homeostasis and its involvement in many water balance disorders , aquaporin-2 , the predominant vasopressin - regulated water channel of the renal collecting duct , is discussed in detail. (
  • Influx of cerebrospinal fluid (CSF) depends upon the expression and perivascular localization of the astroglial water channel aquaporin-4 (AQP4). (
  • Genetic knock-out of the gene encoding the astroglial water channel aquaporin-4, which is importantly involved in paravascular interstitial solute clearance, exacerbated glymphatic pathway dysfunction after TBI and promoted the development of neurofibrillary pathology and neurodegeneration in the post-traumatic brain. (
  • Immunofluorescence and immunoelectron microscopic analyses of dystrophin-null brains revealed a dramatic reduction of AQP4 (aquaporin-4) in astroglial end-feet surrounding capillaries (blood-brain barrier) and at the glia limitans (cerebrospinal fluid-brain interface). (
  • Background: Comparative studies of characteristics of optic neuritis (ON) associated with myelin oligodendrocyte glycoprotein-IgG (MOG-ON) and aquaporin-4-IgG (AQP4-ON) seropositivity are limited. (
  • Amiry-Moghaddam M, Williamson A, Palomba M, Eid T, De Lanerolle NC, Nagelhus EA, Adams ME, Froehner SC, Agre P, Ottersen OP (2003) Delayed K + clearance associated with aquaporin-4 mislocalization: phenotypic defects in brains of α-syntrophin-null mice. (
  • We previously reported that aquaporin-4 deletion (AQP4 -/- ) in mice increased edema and altered blood-brain barrier integrity following intracerebral hemorrhage (ICH). (
  • Aquaporin-4 null mice, backcrossed onto the C57BL/6 background at least 14 times, were obtained from Erlend Nagelhus (University of Oslo, Oslo, Norway) and bred in-house. (
  • Mice lacking the normal expression of aquaporin-4 have decreased cerebral edema, reduced infarct formation and improved neurological outcome induced for classic models of cerebral edema (1, 2, 3). (
  • Brain interstitial fluid dynamics, and therefore AQP-4, are now recognized as essential for two unique functions, namely, neurovascular coupling and glymphatic flow, the brain equivalent of systemic lymphatics. (
  • Nakada T, Kwee IL, Igarashi H, Suzuki Y. Aquaporin-4 Functionality and Virchow-Robin Space Water Dynamics: Physiological Model for Neurovascular Coupling and Glymphatic Flow. (
  • a recently proposed 'glymphatic' clearance mechanism additionally suggests that aquaporin-4 (AQP4) water channels facilitate convective transport through brain parenchyma. (
  • A limited number of aquaporins are found within the central nervous system (CNS): AQP1, 3, 4, 5, 8, 9, and 11, but more exclusive representation of AQP1, 4, and 9 are found in the brain and spinal cord. (
  • Expression and nephron segment-specific distribution of major renal aquaporins (AQP1-4) in Equus caballus, the domestic horse. (
  • The aim of this comparative study was to determine the expression and nephron segment localization of AQP1-4 in Equus caballus by immunoblotting and immunohistochemistry with custom-designed rabbit polyclonal antisera. (
  • Western blots revealed high expression of AQP1-4 in the equine kidney. (
  • Curiously the cerebellum has the highest concentration of the target antigen, but remains the only part of the nervous system yet to demonstrate "characteristic lesions" with aquaporin-4 IgG. (
  • It is based upon a Sandwich assay principle and can be used to detect levels of AQP4 / Aquaporin 4 as low as 0.156 nanograms per millilter. (
  • Isolation of viable Aquaporin-4-specific CD4 + T cells with the CD154 MicroBead Kit, or of CD4 + and CD8 + T cells using the CD137 MicroBead Kit or MACS Cytokine Secretion Assay - Cell Enrichment and Detection Kits. (
  • Description: This is Double-antibody Sandwich Enzyme-linked immunosorbent assay for detection of Rat Protease Activated Receptor 4 (PAR4) in Tissue homogenates, cell lysates and other biological fluids. (
  • Description: Enzyme-linked immunosorbent assay based on the Double-antibody Sandwich method for detection of Rat Protease Activated Receptor 4 (PAR4) in samples from Tissue homogenates, cell lysates and other biological fluids with no significant corss-reactivity with analogues from other species. (
  • Other performances that aquaporin-4 is involved in are synaptic plasticity, astrocyte migration, regulation of extracellular space volume, and the homeostasis of potassium. (
  • The 2003 Nobel Prize in Chemistry was awarded jointly to Peter Agre for the discovery of aquaporins, and Roderick MacKinnon for his work on the structure and mechanism of potassium channels. (
  • Aquaporin-4 exists as two isoforms, a long (M1) isoform with translation initiation at Met-1, and a shorter (M23) isoform with translation initiation at Met-23, with molecular weights around 35-37 kDa and 32-34 kDa, respectively. (
  • Initially associated with the Devic's phenotype, aquaporin-4 IgG has also been consistently found albeit less frequently in tumefactive disease, encephalopathies, classical MS and by one group in GBS. (