tubule
DEFINITION:
A small tube.
arcuate renal tubule - A short, curved part of the distal end of the renal tubule (See below), extending from the distal convoluted tubule (See below) to the straight collecting tubule (See below). Called also junctional (connecting) tubule .
collecting tubule - A channel through which fluids pass from the secreting cells.
connecting tubule - Arcuate renal tubule (See above).
distal convoluted tubule - A distal, rolled-together or coiled part of the ascending limb of the renal tubule (See below), extending from the distal straight tubule (See below) to the junctional (connecting) tubule (See below).
distal straight tubule - Part of the renal tubule (See below) primarily on the ascending limb, extending from the thin tubule (See below) to the distal convoluted tubule (See above).
junctional (connecting) tubule - See arcuate renal tubule (above).
proximal convoluted tubule - The most proximal part of the renal tubule (See below), extending from the glomerular capsule to the proximal straight tubule (See below).
proximal straight tubule - Part of the descending limb of the renal tubule (See below), extending from the thin tubule (See below) to the distal convoluted tubule (See above).
renal collecting tubule - The arcuate renal tubule (See above), straight collecting tubule (See below), and papillary duct considered together. Called also collecting duct .
renal tubule - One of the minute, reabsorptive, secretory, and collecting canals, made up of basement membrane lined with epithelium, that form the substance of the kidneys. See also nephron .
straight collecting tubule - The lower straight part of the renal collecting tubule (See above), extending from the arcuate renal tubule (See above) to the papillary duct.
thin tubule - Part of the renal tubule (See above) at the lower end where the walls are especially thin; it extends from the proximal straight tubule (See above) to the distal straight tubule (See above). In juxtamedullary and deep cortical nephrons it makes up most of the length of Henle's loop.
tubule
DEFINITION:
A small tube.
arcuate renal tubule - A short, curved part of the distal end of the renal tubule (See below), extending from the distal convoluted tubule (See below) to the straight collecting tubule (See below). Called also junctional (connecting) tubule .
collecting tubule - A channel through which fluids pass from the secreting cells.
connecting tubule - Arcuate renal tubule (See above).
distal convoluted tubule - A distal, rolled-together or coiled part of the ascending limb of the renal tubule (See below), extending from the distal straight tubule (See below) to the junctional (connecting) tubule (See below).
distal straight tubule - Part of the renal tubule (See below) primarily on the ascending limb, extending from the thin tubule (See below) to the distal convoluted tubule (See above).
junctional (connecting) tubule - See arcuate renal tubule (above).
proximal convoluted tubule - The most proximal part of the renal tubule (See below), extending from the glomerular capsule to the proximal straight tubule (See below).
proximal straight tubule - Part of the descending limb of the renal tubule (See below), extending from the thin tubule (See below) to the distal convoluted tubule (See above).
renal collecting tubule - The arcuate renal tubule (See above), straight collecting tubule (See below), and papillary duct considered together. Called also collecting duct .
renal tubule - One of the minute, reabsorptive, secretory, and collecting canals, made up of basement membrane lined with epithelium, that form the substance of the kidneys. See also nephron .
straight collecting tubule - The lower straight part of the renal collecting tubule (See above), extending from the arcuate renal tubule (See above) to the papillary duct.
thin tubule - Part of the renal tubule (See above) at the lower end where the walls are especially thin; it extends from the proximal straight tubule (See above) to the distal straight tubule (See above). In juxtamedullary and deep cortical nephrons it makes up most of the length of Henle's loop.
proteins
DEFINITION:
Any of a group of complex organic compounds which contain carbon, hydrogen, oxygen, nitrogen, and usually sulfur, the characteristic element being nitrogen, and which are widely distributed in plants and animals. Proteins, the principal constituents of the protoplasm of all cells, are of high molecular weight and consist essentially of combinations of a-amino acids in peptide linkages. Twenty different amino acids are commonly found in proteins, and each protein has a unique, genetically defined amino acid sequence which determines its specific shape and function. They serve as enzymes, structural elements, hormones, immunoglobulins, etc., and are involved in oxygen transport, muscle contraction, electron transport, and other activities throughout the body, and in photosynthesis.
binding protein - any of a number of plasma proteins (See below) that bind to hormones of low solubility (chiefly the thyroid and steroid hormones), thus providing a transport system for them; some are specific for particular hormones, while others bind to any sparingly soluble hormones. Called also carrier protein or transport protein (See below).
carrier proteins - A binding protein (See above).
plasma proteins - The hundreds of different proteins present in blood plasma, including carrier proteins (such as albumin, transferrin, and haptoglobin), fibrinogen and other coagulation factors, complement components, immunoglobulins, enzyme inhibitors, precursors of substances such as angiotensin and bradykinin, and many other types of proteins.
transport protein - binding protein (See above).
The renal collecting duct exhibits functional heterogeneity that is a reflection of the differential expression of transporter proteins along the length of the tubule. We have previously reported a significant change in the expression of several major solute transporter proteins in the inner medulla of aquaporin 1 deficient mice (AQP1 -/-) resulting in a “corticalization” of the inner medullary collecting duct (IMCD) (Faseb J. 15(5) 2001). Here we have examined the mRNA levels of these transporters using real time RT-PCR as well as the physiology of the IMCD using the isolated perfused tubule technique. Vasopressin significantly increased the urea permeability of the IMCD from control mice while having no effect in IMCD from AQP1(-/-) mice. Finally we examined the expression profile of inner medullary transporters in another mouse model of nephrogenic diabetes insipidus: the CLC-nk1 (-/-) mouse. As in the AQP1 (-/-) mice, expression of b and g ENAC were significantly increased while UT A expression was significantly decreased in the inner medulla of the CLC-nK1 (-/-) mouse. Thus, both models exhibit changes in gene expression in the IMCD resulting in a “cortical-like” phenotype.