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.

physiology

DEFINITION:

1. The science which treats of the functions of the living organism and its parts, and of the physical and chemical factors and processes involved.

2. The basic processes underlying the functioning of a species or class of organism, or any of its parts or processes.

aquaporins

DEFINITION:

A family of membrane channel proteins that serve as selective pores through which water crosses the plasma membranes of many human tissues and cell types.

physiological

DEFINITION:

1. Of or pertaining to physiology.
2. Characteristic of or appropriate to an organism's healthy or normal functioning.
3. Differing in, involving, or affecting physiological factors.

aquaporins

DEFINITION:

A family of membrane channel proteins that serve as selective pores through which water crosses the plasma membranes of many human tissues and cell types.

elucidated

DEFINITION:

Made lucid (clear) especially by explanation or analysis; to give a clarifying explanation.

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.

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.

expressed

DEFINITION:

1. Showing a detectable effect of a gene.

2. Made known; shown.

3. Squeezed out; extracted by pressing.

renal collecting duct

DEFINITION:

Also known as the tubulus renalis colligens, or renal collecting tubule: That structure of the kidney consisting of the arcuate renal tubule, straight collecting tubule, and papillary duct considered together.

apical membrane

DEFINITION:

See under membrane.

intracellular

DEFINITION:

Situated or occurring within a cell or cells.

binding

DEFINITION:

1. Wrapping with a binder or bandage.

2. Forming a weak, reversible chemical bond, e.g., antigen to antibody or hormone to receptor.

antidiuretic hormone

DEFINITION:

See vasopressin.

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).

receptor

DEFINITION:

1. A molecular structure within a cell or on the surface characterized by (1) selective binding of a specific substance and (2) a specific physiologic effect that accompanies the binding, e.g., membrane receptors for peptide hormones, neurotransmitters, antigens, complement fragments, and immunoglobulins and nuclear receptors for steroid hormones.

2. A sensory nerve terminal that responds to stimuli of various kinds; classified in various ways including by the type of stimulus and by the location in the body.

V2 receptor - The structure to which the antidiuretic hormone, arginine vasopressin binds.

pathological

DEFINITION:

Pertaining to pathology.

characterized

DEFINITION:

Marked or distinguished as a characteristic.

reabsorption

DEFINITION:

The act or process of absorbing again, as the selective absorption by the kidneys of substances (glucose, proteins, sodium, etc.) already secreted into the renal tubules, and their return to the circulating blood.

urine

DEFINITION:

The fluid excreted by the kidneys, passed through the ureters, stored in the bladder, and discharged through the urethra. Urine, in health, has an amber color, a slight acid reaction, a peculiar odor, and a bitter, saline taste.

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).

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.

AQP2 mutations

DEFINITION:

Mutations occurring in the aquaporin-2 gene.

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.

kidney

DEFINITION:

One of a pair of vertebrate organs situated in the body cavity near the spinal column that excrete waste products of metabolism, in man are bean-shaped organs about 4-1/2 inches long lying behind the peritoneum in a mass of fatty tissue, and consist chiefly of nephrons by which urine is secreted, collected, and discharged into a main cavity whence it is conveyed by the ureter to the bladder.

concentrate

DEFINITION:

1. To bring to a common center; to gather together at one point.

2. To increase the strength by diminishing the bulk of, as of a liquid; to condense.

3. A drug or other preparation that has been strengthened by the evaporation of its non-active parts.

urine

DEFINITION:

The fluid excreted by the kidneys, passed through the ureters, stored in the bladder, and discharged through the urethra. Urine, in health, has an amber color, a slight acid reaction, a peculiar odor, and a bitter, saline taste.

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).

renal

DEFINITION:

Pertaining to the kidney.

uptake

DEFINITION:

Absorption and incorporation of a substance by living tissue.

apical membrane

DEFINITION:

See under membrane.

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).

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.

aquaporins

DEFINITION:

A family of membrane channel proteins that serve as selective pores through which water crosses the plasma membranes of many human tissues and cell types.

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.

constitutively

DEFINITION:

Being produced constantly or in fixed amounts, regardless of environmental conditions or demand.

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.

shuttling

DEFINITION:

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

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.

apical membrane

DEFINITION:

See under membrane.

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.

routing

DEFINITION:

1. A course or way.

2. The area of the body through which a curative is introduced.

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.

collecting duct cells

DEFINITION:

The cells of the renal collecting tubule: the arcuate renal tubule, straight collecting tubule, and papillary duct considered together.

misrouting

DEFINITION:

Sending through or on the wrong channel or course.

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.

mutants

DEFINITION:

1. Genes or organisms that have undergone genetic mutation.

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.