aquaporin-2

DEFINITION:

Also called WCH-CD, this water channel makes the principal cells of the inner medullary collecting duct in the kidneys more permeable to water. Lack of functional aquaporin-2 gene leads to a rare form of nephrogenic diabetes insipidus.

AQP-2

DEFINITION:

Aquaporin-2.

component

DEFINITION:

A constituent element or part.

vasopressin

DEFINITION:

1. One of two octapeptide hormones formed by the neuronal cells of the hypothalamic nuclei and stored in the posterior lobe of the pituitary gland (neurohypophysis), the other being oxytocin. It stimulates the contraction of the muscular tissue of the capillaries and arterioles, raising the blood pressure. It promotes contraction of the intestinal musculature and increases peristalsis, and also exerts some contractile influence on the uterus. It also has a specific effect on the epithelial cells of the distal portion of the uriniferous tubule, augmenting resorption of water independently of solutes, resulting in concentration of urine and dilution of blood serum. Its rate of secretion is regulated chiefly by the osmolarity of the plasma.

2. [USP], A pharmaceutical preparation of the same principle, prepared synthetically or obtained from the posterior pituitary of healthy domestic animals used for food by man; used mainly as an antidiuretic in the treatment of acute or chronic diabetes insipidus, administered intramuscularly as a test of hypothalamo-neurohypophysial-renal function in distinguishing central from nephrogenic diabetes insipidus; it may also be used to stimulate smooth muscle tissue, especially to induce vasoconstriction in the presence of hemorrhage. Called also antidiuretic hormone (ADH).

regulated

DEFINITION:

1. Having been adjusted to a certain standard.

2. In biology, describing the adaptation of form or behavior of an organism to changed conditions.

antidiuretic

DEFINITION:

1. Suppressing the rate of urine formation.

2. An agent that suppresses urine formation.

water channel

DEFINITION:

A channel in the plasma membrane of plant and animal cells that permits passage of water molecules; chemical substances such as vasopressin cause the opening of new channels and increase permeability.

regulated

DEFINITION:

1. Having been adjusted to a certain standard.

2. In biology, describing the adaptation of form or behavior of an organism to changed conditions.

hormone

DEFINITION:

A product of living cells that circulates in body fluids and produces a specific effect on the activity of cells remote from its point of origin; especially: one exerting a stimulatory effect on a cellular activity.

hypophysiotropic hormones - Hormones produced by the hypothalamus, usually releasing hormones (see below), which maintain the endocrine functions of cells of the adenohypophysis.

neurohormone - A hormone secreted by a specialized neuron into the bloodstream, the cerebrospinal fluid, or the intercellular spaces of the nervous system.

releasing hormones - Hormones elaborated in one structure that cause the release of hormones from another structure, such as those from the hypothalamus that act on the adenohypophysis. The term is applied to substances of established chemical identity, whereas substances of unknown chemical structure are called releasing factors .

regulate

DEFINITION:

1. To adjust to a certain standard.
2. In biology, to adapt the form or behavior of an organism to changed conditions.
3. To possess the power to form a whole embryo from stages before the gastrula.

expression

DEFINITION:

1. The aspect or appearance of the face (or surface of a cell) as determined by the physical or emotional state.

2. The act of squeezing or evacuating by pressure; a term used in pharmacy, surgery, and obstetrics.

3. The detectable effect of a gene.

4. A representation of value, relation, or the like (e.g., ratio).

AQP-2

DEFINITION:

Aquaporin-2.

culture

DEFINITION:

1. The propagation of microorganisms or of living tissue cells in special media conducive to their growth.

2. A growth of microorganisms or other living cells.

3. To induce the propagation of microorganisms or living tissue cells in media conducive to their growth.

4. The customary beliefs, social form, and material traits of a racial, religious, or social group.

expression

DEFINITION:

1. The aspect or appearance of the face (or surface of a cell) as determined by the physical or emotional state.

2. The act of squeezing or evacuating by pressure; a term used in pharmacy, surgery, and obstetrics.

3. The detectable effect of a gene.

4. A representation of value, relation, or the like (e.g., ratio).

AQP-2

DEFINITION:

Aquaporin-2.

collagen

DEFINITION:

The protein substance of the white fibers (collagenous fibers) of skin, tendon, bone, cartilage, and all other connective tissue; composed of molecules of tropocollagen, it is converted into gelatin by boiling.

additive

DEFINITION:

1. Characterized by addition.

2. A substance, as a flavoring agent, preservative, or vitamin, added to another substance (such as a food or drug) that is to be ingested.

immunofluorescence

DEFINITION:

The labeling of antigens or antibodies with fluorescent dyes
for the purpose of demonstrating the presence of corresponding antibodies or antigens in a
tissue preparation or smear.

shuttling

DEFINITION:

In biochemistry, referring to a mechanism for the transport of electrons or an organic group, or both, across a membrane.

AQP-2

DEFINITION:

Aquaporin-2.

vesicles

DEFINITION:

1. Small bladders or sacs containing liquid.
2. Small circumscribed epidermal elevations, usually containing a clear fluid.

vasopressin

DEFINITION:

1. One of two octapeptide hormones formed by the neuronal cells of the hypothalamic nuclei and stored in the posterior lobe of the pituitary gland (neurohypophysis), the other being oxytocin. It stimulates the contraction of the muscular tissue of the capillaries and arterioles, raising the blood pressure. It promotes contraction of the intestinal musculature and increases peristalsis, and also exerts some contractile influence on the uterus. It also has a specific effect on the epithelial cells of the distal portion of the uriniferous tubule, augmenting resorption of water independently of solutes, resulting in concentration of urine and dilution of blood serum. Its rate of secretion is regulated chiefly by the osmolarity of the plasma.

2. [USP], A pharmaceutical preparation of the same principle, prepared synthetically or obtained from the posterior pituitary of healthy domestic animals used for food by man; used mainly as an antidiuretic in the treatment of acute or chronic diabetes insipidus, administered intramuscularly as a test of hypothalamo-neurohypophysial-renal function in distinguishing central from nephrogenic diabetes insipidus; it may also be used to stimulate smooth muscle tissue, especially to induce vasoconstriction in the presence of hemorrhage. Called also antidiuretic hormone (ADH).

forskolin

DEFINITION:

Activator of adenylate cyclase leading to an increase in the intracellular concentration of cAMP.

(Sources: A. Laurenza, et al., Trends Pharm. Sci. 10: 442-447 (1989) and R. Barber and T.J. Goka, J. Cyclic Nucleotide Protein Phos. Res. 10:23-29 (1985) @www.lclabs.com/PROFILE/D-F/F-9929.php4.)

collagen

DEFINITION:

The protein substance of the white fibers (collagenous fibers) of skin, tendon, bone, cartilage, and all other connective tissue; composed of molecules of tropocollagen, it is converted into gelatin by boiling.

cAMP

DEFINITION:

Cyclic AMP (cyclic adenosine monophosphate).

vasopressin

DEFINITION:

1. One of two octapeptide hormones formed by the neuronal cells of the hypothalamic nuclei and stored in the posterior lobe of the pituitary gland (neurohypophysis), the other being oxytocin. It stimulates the contraction of the muscular tissue of the capillaries and arterioles, raising the blood pressure. It promotes contraction of the intestinal musculature and increases peristalsis, and also exerts some contractile influence on the uterus. It also has a specific effect on the epithelial cells of the distal portion of the uriniferous tubule, augmenting resorption of water independently of solutes, resulting in concentration of urine and dilution of blood serum. Its rate of secretion is regulated chiefly by the osmolarity of the plasma.

2. [USP], A pharmaceutical preparation of the same principle, prepared synthetically or obtained from the posterior pituitary of healthy domestic animals used for food by man; used mainly as an antidiuretic in the treatment of acute or chronic diabetes insipidus, administered intramuscularly as a test of hypothalamo-neurohypophysial-renal function in distinguishing central from nephrogenic diabetes insipidus; it may also be used to stimulate smooth muscle tissue, especially to induce vasoconstriction in the presence of hemorrhage. Called also antidiuretic hormone (ADH).

water permeability

DEFINITION:

The property or state of being permeable to water.

exocytotic

DEFINITION:

Pertaining to exocytosis.

apical membrane

DEFINITION:

See under membrane.

principal cells

DEFINITION:

1. The fundamental cells of an organ, which usually have a specific function.

2. The principal cells are the chief cells, i.e., the most abundant cells of the parathyroid glands, being polygonal epithelial cells with a granular cytoplasm and vesicular nuclei, arranged in plates or cords, and which are rich in glycogen: the clear cells are more numerous and have relatively large nuclei and clear cytoplasm with few granules, while the dark cells are smaller with smaller and darker nuclei and finely granular cytoplasm with many granules. Intermediate forms also exist.

capacitance

DEFINITION:

1. The property of being able to store an electric charge.

2. The ratio of the charge stored by a capacitor to the voltage across the capacitor. Symbol C. Formerly called capacity. The SI unit of capacitance is the farad.

fusion

DEFINITION:

1. The act, process, or result of melting.

2. The merging or coherence of adjacent parts or bodies.

3. The coordination of the separate images of the same object in the two eyes into one.

4. The operative formation of an ankylosis or arthrodesis.

membrane

DEFINITION:

A thin layer of tissue which covers a surface, lines a cavity, or divides a space or organ.

apical membrane - Pertaining to or located at the apex.

basolateral membrane - Pertaining to the base and sides.

plasma membrane - The structure enveloping a cell, enclosing the cytoplasm, and forming a selective permeability barrier; it consists of lipids, proteins, and some carbohydrates, the lipids thought to form a bilayer in which integral proteins are embedded to varying degrees.

postsynaptic membrane - The area of plasma membrane of a postsynaptic cell, either a muscle fiber or a neuron, that is within the synapse and has areas especially adapted for receiving neurotransmitters.

presynaptic membrane - Area of the plasma membrane of a presynaptic axon that is within the synapse and has sites (active zones) especially adapted for the release of neurotransmitters.

semipermeable membrane - A membrane that permits the passage of a solvent, such as water, but prevents the passage of the dissolved substance, or solute.

capacitance

DEFINITION:

1. The property of being able to store an electric charge.

2. The ratio of the charge stored by a capacitor to the voltage across the capacitor. Symbol C. Formerly called capacity. The SI unit of capacitance is the farad.

expressed

DEFINITION:

1. Showing a detectable effect of a gene.

2. Made known; shown.

3. Squeezed out; extracted by pressing.

AQP-2

DEFINITION:

Aquaporin-2.

cell

DEFINITION:

1. Any one of the minute protoplasmic masses that make up organized tissue, consisting of a nucleus which is surrounded by cytoplasm which contains the various organelles and is enclosed in the cell or plasma membrane. A cell is the fundamental, structural, and functional unit of living organisms.

2. A small, more or less closed space.

neuroglial cells - The cells of the supportive tissue of the central nervous system (neuroglia); these non-neural cells are of three kinds: astrocytes, oligodendrocytes (collectively termed macroglia) and microglia.

reticular cells - The cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow, and spleen are part of the reticuloendothelial system and under appropriate stimulation may differentiate into macrophages.

stem cell - 1. Any precursor cell.

2. A blood cell progenitor, or mother cell, having the capacity for both replication and differentiation, and giving rise to various morphologically recognizable precursors of different blood cell lines, such as the proerythrocyte and myeloblast, which cannot self-replicate and must differentiate into more mature daughter cells.

forskolin

DEFINITION:

Activator of adenylate cyclase leading to an increase in the intracellular concentration of cAMP.

(Sources: A. Laurenza, et al., Trends Pharm. Sci. 10: 442-447 (1989) and R. Barber and T.J. Goka, J. Cyclic Nucleotide Protein Phos. Res. 10:23-29 (1985) @www.lclabs.com/PROFILE/D-F/F-9929.php4.)

incubation

DEFINITION:

1. The development of the embryo in the eggs of oviparous animals.

2. The maintenance of an environment with controlled temperature, humidity, and oxygen for the development of an infant, especially of a premature one.

3. The development of an infectious disease from the entrance of the pathogen to the appearance of clinical symptoms.

4. The development of microorganisms or other cells in an appropriate medium under controlled environmental conditions, especially of temperature, to permit optimum growth.

5. The process of maintaining reaction mixtures at a given temperature for specified time periods for the development of chemical or enzymatic reactions.

cell

DEFINITION:

1. Any one of the minute protoplasmic masses that make up organized tissue, consisting of a nucleus which is surrounded by cytoplasm which contains the various organelles and is enclosed in the cell or plasma membrane. A cell is the fundamental, structural, and functional unit of living organisms.

2. A small, more or less closed space.

neuroglial cells - The cells of the supportive tissue of the central nervous system (neuroglia); these non-neural cells are of three kinds: astrocytes, oligodendrocytes (collectively termed macroglia) and microglia.

reticular cells - The cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow, and spleen are part of the reticuloendothelial system and under appropriate stimulation may differentiate into macrophages.

stem cell - 1. Any precursor cell.

2. A blood cell progenitor, or mother cell, having the capacity for both replication and differentiation, and giving rise to various morphologically recognizable precursors of different blood cell lines, such as the proerythrocyte and myeloblast, which cannot self-replicate and must differentiate into more mature daughter cells.

cell

DEFINITION:

1. Any one of the minute protoplasmic masses that make up organized tissue, consisting of a nucleus which is surrounded by cytoplasm which contains the various organelles and is enclosed in the cell or plasma membrane. A cell is the fundamental, structural, and functional unit of living organisms.

2. A small, more or less closed space.

neuroglial cells - The cells of the supportive tissue of the central nervous system (neuroglia); these non-neural cells are of three kinds: astrocytes, oligodendrocytes (collectively termed macroglia) and microglia.

reticular cells - The cells forming the reticular fibers of connective tissue; those forming the framework of lymph nodes, bone marrow, and spleen are part of the reticuloendothelial system and under appropriate stimulation may differentiate into macrophages.

stem cell - 1. Any precursor cell.

2. A blood cell progenitor, or mother cell, having the capacity for both replication and differentiation, and giving rise to various morphologically recognizable precursors of different blood cell lines, such as the proerythrocyte and myeloblast, which cannot self-replicate and must differentiate into more mature daughter cells.

agent

DEFINITION:

Any power, principle, or substance capable of producing an effect, whether physical, chemical, or biological.

subsequent

DEFINITION:

Following after; succeeding.

inhibition

DEFINITION:

Arrest or restraint of a process.

model

DEFINITION:

1. Something that represents or simulates something else; a replica.
2. A reasonable facsimile of the body or any of its parts; used for demonstration and teaching purposes.
3. Cast, definition 5.
4. To imitate another's behavior; See modeling .
5. A hypothesis or theory.

antidiuretic

DEFINITION:

1. Suppressing the rate of urine formation.

2. An agent that suppresses urine formation.

vasopressin

DEFINITION:

1. One of two octapeptide hormones formed by the neuronal cells of the hypothalamic nuclei and stored in the posterior lobe of the pituitary gland (neurohypophysis), the other being oxytocin. It stimulates the contraction of the muscular tissue of the capillaries and arterioles, raising the blood pressure. It promotes contraction of the intestinal musculature and increases peristalsis, and also exerts some contractile influence on the uterus. It also has a specific effect on the epithelial cells of the distal portion of the uriniferous tubule, augmenting resorption of water independently of solutes, resulting in concentration of urine and dilution of blood serum. Its rate of secretion is regulated chiefly by the osmolarity of the plasma.

2. [USP], A pharmaceutical preparation of the same principle, prepared synthetically or obtained from the posterior pituitary of healthy domestic animals used for food by man; used mainly as an antidiuretic in the treatment of acute or chronic diabetes insipidus, administered intramuscularly as a test of hypothalamo-neurohypophysial-renal function in distinguishing central from nephrogenic diabetes insipidus; it may also be used to stimulate smooth muscle tissue, especially to induce vasoconstriction in the presence of hemorrhage. Called also antidiuretic hormone (ADH).

in vitro

DEFINITION:

Within a glass; observable in a test tube; in an artificial environment.

cellular

DEFINITION:

Pertaining to, or made up of, cells.

regulation

DEFINITION:

1. The act of adjusting or state or being adjusted to a certain standard.
2. In biology, the adaptation of form or behavior of an organism to changed conditions.
3. The power to form a whole embryo from stages before the gastrula.

genes

DEFINITION:

In the singular: A segment of a DNA molecule that contains all the information required for synthesis of a product (polypeptide chain or RNA molecule), including both coding and non-coding sequences. It is the biological unit of heredity, self-reproducing, and transmitted from parent to progeny. Each gene has a specific position (locus) on the chromosome map. From the standpoint of function, genes are conceived of as structural, operator, and regulatory genes.

wild-type gene - The normal allele of a gene, sometimes symbolized by +.

X-linked gene - A gene carried on the X chromosome; the corresponding trait, whether dominant or recessive, is always expressed in males, who have only one X chromosome. X linkage is used sometimes synonymously with sex linkage since no genetic disorders have as yet been associated with genes on the Y chromosome.

encoding

DEFINITION:

The process of converting (as a body of information) from one system of communication into another; esp.: to convert (a message) into code.

antidiuretic

DEFINITION:

1. Suppressing the rate of urine formation.

2. An agent that suppresses urine formation.

pharmacological

DEFINITION:

Pertaining to pharmacology or to the properties and reactions of drugs.

congenital

DEFINITION:

Existing at, and usually before, birth; referring to conditions that are present at birth, regardless of their causation.

acquired

DEFINITION:

Not genetic, but produced by influences originating outside the organism.

diuretic

DEFINITION:

1. Increasing the excretion of urine.

2. An agent that promotes the excretion of urine.

aquaporin-2

DEFINITION:

Also called WCH-CD, this water channel makes the principal cells of the inner medullary collecting duct in the kidneys more permeable to water. Lack of functional aquaporin-2 gene leads to a rare form of nephrogenic diabetes insipidus.

expression

DEFINITION:

1. The aspect or appearance of the face (or surface of a cell) as determined by the physical or emotional state.

2. The act of squeezing or evacuating by pressure; a term used in pharmacy, surgery, and obstetrics.

3. The detectable effect of a gene.

4. A representation of value, relation, or the like (e.g., ratio).

J

DEFINITION:

Symbol for joule .

water-transporting protein

DEFINITION:

Protein that binds to water and provides a transport system for it.

aquaporin-2

DEFINITION:

Also called WCH-CD, this water channel makes the principal cells of the inner medullary collecting duct in the kidneys more permeable to water. Lack of functional aquaporin-2 gene leads to a rare form of nephrogenic diabetes insipidus.

AQP-2

DEFINITION:

Aquaporin-2.

viable

DEFINITION:

Capable of living.

functional

DEFINITION:

1. Of or pertaining to a function.

2. Affecting the function but not the structure.

cells

DEFINITION:

See definitions for "cell."

antidiuretic

DEFINITION:

1. Suppressing the rate of urine formation.

2. An agent that suppresses urine formation.

vasopressin

DEFINITION:

1. One of two octapeptide hormones formed by the neuronal cells of the hypothalamic nuclei and stored in the posterior lobe of the pituitary gland (neurohypophysis), the other being oxytocin. It stimulates the contraction of the muscular tissue of the capillaries and arterioles, raising the blood pressure. It promotes contraction of the intestinal musculature and increases peristalsis, and also exerts some contractile influence on the uterus. It also has a specific effect on the epithelial cells of the distal portion of the uriniferous tubule, augmenting resorption of water independently of solutes, resulting in concentration of urine and dilution of blood serum. Its rate of secretion is regulated chiefly by the osmolarity of the plasma.

2. [USP], A pharmaceutical preparation of the same principle, prepared synthetically or obtained from the posterior pituitary of healthy domestic animals used for food by man; used mainly as an antidiuretic in the treatment of acute or chronic diabetes insipidus, administered intramuscularly as a test of hypothalamo-neurohypophysial-renal function in distinguishing central from nephrogenic diabetes insipidus; it may also be used to stimulate smooth muscle tissue, especially to induce vasoconstriction in the presence of hemorrhage. Called also antidiuretic hormone (ADH).

cellular

DEFINITION:

Pertaining to, or made up of, cells.

AQP-2

DEFINITION:

Aquaporin-2.

cells

DEFINITION:

See definitions for "cell."

downregulation

DEFINITION:

A decrease in the number of receptors for a chemical or drug on cell surfaces in a given area, usually due to long-term exposure to the agent. (Dorland's Illustrated Medical Dictionary, 29th edition)

Downregulation of aquaporin 2: The number of aquaporin 2 water channels will be decreased, i.e., regulated to a lower number of channels expressed on the luminal membrane (D. Bichet).

Downregulation of AQP2 means that there are many conditions with acquired nephrogenic diabetes insipidus (vasopressin-resistent polyuria) which result in a reduction in the levels of AQP2 protein in the collecting duct cells. Since AQP2 is essential for reabsorption of water from the collecting duct lumen back to the circulation, the absence or reduced levels of AQP2 (downregulation) results in the development of polyuria. Thus the conditions associated with this downregulation of AQP2 share many common features with the inherited forms of NDI (with mutations in vasopressin V2 receptor) since this condition is also associated with a reduced/absence of regulation of AQP2. This regulation is important for keeping the levels of AQP2 protein up, but it is also extremely important in regulating the trafficking of AQP2 from the reservoir in small vesicles to the apical plasma membrane (its active site for water reabsorption—the site where the water channel faces the water to be reabsorbed). This is why the studies of the very common acquired forms of NDI are very important in connection with inherited NDI (the shared elements of regulation or rather dysregulation) (S. Nielsen).

AQP-2

DEFINITION:

Aquaporin-2.

nephrogenic diabetes insipidus

DEFINITION:

A syndrome of polyuria and hyposthenuria caused by the failure of the renal tubules to reabsorb water in response to antidiuretic hormone, without disturbance in the renal filtration and solute excretion rates; the condition does not respond to exogenous vasopressin. It may be inherited as a rare X-linked trait or be acquired as a result of drug therapy or systemic disease.

NDI

DEFINITION:

Nephrogenic diabetes insipidus.

promote

DEFINITION:

1. To advance in station, rank, or honor.

2. To contribute to the growth or prosperity of; further.

3. Launch.

NDI

DEFINITION:

Nephrogenic diabetes insipidus.

urination

DEFINITION:

The discharge or passage of urine.