urea

DEFINITION:

A soluble weakly basic nitrogenous compound CO(NH₂)₂ that is the chief solid component of mammalian urine and an end product of protein decomposition, is synthesized from carbon dioxide and ammonia, and is used especially in synthesis (as of resins and plastics) and in fertilizers and animal rations.

renal medulla

DEFINITION:

The inner part of the substance of the kidney, composed chiefly of collecting tubule elements, loops of Henle, and vasa recta, organized grossly into pyramids.

cellular

DEFINITION:

Pertaining to, or made up of, cells.

subcellular

DEFINITION:

Below the cellular level.

localization

DEFINITION:

1. The determination of the site or place of any process or lesion.
2. Restriction to a circumscribed or limited area.
3. Prelocalization.

affinity-purified

DEFINITION:

Carried out by means of affinity chromatography.

cloned

DEFINITION:

Propagated or copied.

immunoblots

DEFINITION:

A technique for, or the blots resulting from, analyzing or identifying proteins via antigen - antibody specific reactions, as in Western blot or dot blot techniques.

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.

fractions

DEFINITION:

1. Portions of something larger.

2. In chemistry, referring to the separable constituents of a substance.

band

DEFINITION:

An elongated area with parallel or roughly parallel borders that is distinct from the surrounding surface by its color, texture, or other characteristics. See chromosome band.

immunocytochemistry

DEFINITION:

The biochemistry of cellular immunology.

apical

DEFINITION:

Pertaining to or located at the apex.

subapical

DEFINITION:

Situated inferior to an apex.

inner medullary collecting duct

DEFINITION:

The distal part of the renal tubule, including the loop of Henle, lying within the medulla.

IMCD

DEFINITION:

Inner medullary collecting duct.

cells

DEFINITION:

See definitions for "cell."

labeling

DEFINITION:

1. The marking, tagging, or act of identifying something.
2. Providing something with such a characteristic.

radioactive labeling - the marking of a compound by incorporating a radioisotope into it.

medullary

DEFINITION:

Pertaining to the marrow or to any medulla; resembling marrow.

cortical

DEFINITION:

Pertaining to or of the nature of a cortex or bark.

collecting ducts

DEFINITION:

Renal collecting tubules: the arcuate renal tubule, straight collecting tubule, and papillary duct considered together.

labeling

DEFINITION:

1. The marking, tagging, or act of identifying something.
2. Providing something with such a characteristic.

radioactive labeling - the marking of a compound by incorporating a radioisotope into it.

apical plasma membrane

DEFINITION:

Indicating the apex of the plasma membrane.

IMCD cells

DEFINITION:

Inner medullary collecting duct (IMCD) cells.

labeling

DEFINITION:

1. The marking, tagging, or act of identifying something.
2. Providing something with such a characteristic.

radioactive labeling - the marking of a compound by incorporating a radioisotope into it.

basolateral plasma membrane

DEFINITION:

Pertaining to the base and sides or situated at the base and sides of the plasma membrane.

immunoblots

DEFINITION:

A technique for, or the blots resulting from, analyzing or identifying proteins via antigen - antibody specific reactions, as in Western blot or dot blot techniques.

plasma membrane

DEFINITION:

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.

inner medulla

DEFINITION:

Inner medulla of kidney: inner zone of renal medulla.

subcellular

DEFINITION:

Below the cellular level.

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.

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.

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.

outer medulla

DEFINITION:

See outer medulla of kidney.

IMCD

DEFINITION:

Inner medullary collecting duct.

descending thin limbs

DEFINITION:

See under loop of Henle and limb.

labeled

DEFINITION:

Having been marked, tagged, or characterized in some way to identify something.

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.

apical

DEFINITION:

Pertaining to or located at the apex.

pathway

DEFINITION:

1. A path or course, especially a course followed in the attainment of a specific end.
2. The nerve structures through which an impulse passes between groups of nerve cells or between the central nervous system and an organ or muscle.
3. Metabolic pathway.

IMCD

DEFINITION:

Inner medullary collecting duct.

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).

trafficking

DEFINITION:

Acting as a transporter.

apical plasma membrane

DEFINITION:

Indicating the apex of the plasma membrane.

pathway

DEFINITION:

1. A path or course, especially a course followed in the attainment of a specific end.
2. The nerve structures through which an impulse passes between groups of nerve cells or between the central nervous system and an organ or muscle.
3. Metabolic pathway.

urea

DEFINITION:

A soluble weakly basic nitrogenous compound CO(NH₂)₂ that is the chief solid component of mammalian urine and an end product of protein decomposition, is synthesized from carbon dioxide and ammonia, and is used especially in synthesis (as of resins and plastics) and in fertilizers and animal rations.

nephrons

DEFINITION:

The anatomical and functional unit of the kidney, consisting of the renal corpuscle, the proximal convoluted tubule, the descending and ascending limbs of Henle's loop, the distal convoluted tubule, and the collecting tubule.

permission

DEFINITION:

Formal consent; authorization.