aquaporin (AQP) water channels

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.

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.

constitutively

DEFINITION:

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

expressed

DEFINITION:

1. Showing a detectable effect of a gene.

2. Made known; shown.

3. Squeezed out; extracted by pressing.

AQP1

DEFINITION:

Aquaporin-1.

proximal tubule

DEFINITION:

See proximal convoluted tubule or proximal straight tubule under tubule .

descending limb

DEFINITION:

1. The proximal part of the loop of Henle (ansa nephroni).

2. The descending portion of a tracing of the pulse wave obtained by the manometer or the sphygmograph.

absorption

DEFINITION:

1. The uptake of substances into or across tissues, e.g., skin, intestine, and kidney tubules.


2. In radiology, the taking up of energy by matter with which the radiation interacts.

counter-current multiplication system

DEFINITION:

See "countercurrent multiplication."

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.

shuttling

DEFINITION:

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

AQP2

DEFINITION:

Aquaporin-2.

antidiuresis

DEFINITION:

Suppression of urinary excretion.

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.

water balance

DEFINITION:

Fluid balance.

genetic

DEFINITION:

1. Relating to or determined by the origin, development, or causal antecedents of something.

2. Of, relating to, or being a gene.

AQPs

DEFINITION:

Aquaporins.

pathological

DEFINITION:

Pertaining to pathology.

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).

renal

DEFINITION:

Pertaining to the kidney.

AQP2

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.

aquaporin

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.

capillaries

DEFINITION:

1. Pertaining to or resembling a hair.

2. Any of the minute vessels that connect the arterioles and venules, forming a network in nearly all parts of the body. Their walls act as semipermeable membranes for the interchange of various substances, including fluids, between the blood and tissue fluid.

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).

AQP1

DEFINITION:

Aquaporin-1.