WordNet

situated farthest from point of attachment or origin, as of a limb or bone
directed away from the midline or mesial plane of the body
a small tube

PrepTutorEJDIC

中心から遠い,末梢(まっしょう)[部]の,末端[部]の
小管,細管

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/12/19 03:03:10」(JST)

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The distal convoluted tubule (DCT) is a portion of kidney nephron between the loop of Henle and the collecting duct system.

Physiology

It is partly responsible for the regulation of potassium, sodium, calcium, and pH. It is the primary site for the kidneys' hormone based regulation of calcium (Ca).

On its apical surface (lumen side), cells of the DCT have a thiazide-sensitive Na-Cl cotransporter and are permeable to Ca, via the TRPV5 channel. On the basolateral surface (blood) there is an ATP-dependent Na/K antiporter pump, a secondary active Na/Ca transporter, and an ATP dependent Ca transporter. The basolateral ATP dependent Na/K pump produces the gradient for Na to be absorbed from the apical surface via the Na/Cl symporter, and for Ca to be reclaimed into the blood by the Na/Ca basolateral antiporter.

It regulates pH by absorbing bicarbonate and secreting protons (H⁺) into the filtrate, or by absorbing protons and secreting bicarbonate into the filtrate.

Sodium and potassium levels are controlled by secreting K⁺ and absorbing Na⁺. Sodium absorption by the distal tubule is mediated by the hormone aldosterone. Aldosterone increases sodium reabsorption. Sodium and chloride (salt) reabsorption is also mediated by a group of kinases called WNK kinases. There are 4 different WNK kinases, WNK1, WNK2, WNK3, and WNK4.

It also participates in calcium regulation by reabsorbing Ca²⁺ in response to parathyroid hormone.^[1] PTH effect is mediated through phosphorylation of regulatory proteins and enhancing the synthesis of all transporters within the distal convoluted tubule.

Arginine vasopressin receptor 2 is also expressed in the DCT.

Clinical significance

Thiazide diuretics inhibit Na⁺/Cl⁻ reabsorption from the DCT by blocking the thiazide-sensitive Na-Cl cotransporter.

By inhibiting the cotransporter, thiazide diuretics increase the gradient potential for Na. This increases the activity of the basolateral Na/Ca antiport and causes the increase in calcium reclamation associated with thiazide diuretics.

Histology

The DCT is lined with simple cuboidal cells that are shorter than those of the proximal convoluted tubule (PCT). The lumen appears larger in DCT than the PCT lumen because the PCT has a brush border (microvilli). DCT can be recognized by its numerous mitochondria, basal infoldings and lateral membrane interdigitations with neighboring cells.

The point where DCT contacts afferent arteriole of renal corpuscle is called macula densa. It has tightly packed columnar cells which display reversed polarity and may monitor the osmolarity of blood.

Histologically, cells of the DCT can be differentiated from cells of the proximal convoluted tubule:

Characteristic	PCT	DCT
Apical brush border	Usually present	Not present
Eosinophilicity	More	Less
Cytoplasm	More	Less
Readily discernible nuclei	Less likely	More likely

Additional images

1 Glomerulus, 2 proximal tubule, 3 distal tubule
Transverse section of pyramidal substance of kidney of pig, the bloodvessels of which are injected.
Renal corpuscle
Diagram outlining movement of ions in nephron.

References

^ MedEd at Loyola mech/cases/case24/kidney.htm

External links

Histology image: 35_19 at the University of Oklahoma Health Sciences Center
Physiology: 7/7ch03/7ch03p18 - Essentials of Human Physiology
Physiology: 7/7ch07/7ch07p14 - Essentials of Human Physiology
Histology image: 16004loa – Histology Learning System at Boston University
Histology image: 16007loa – Histology Learning System at Boston University

UpToDate Contents

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1. 利尿剤とカルシウムバランス diuretics and calcium balance
2. バーター症候群およびギテルマン症候群 bartter and gitelman syndromes
3. アムホテシリンBによる腎毒性 amphotericin b nephrotoxicity
4. 利尿剤の作用機序 mechanism of action of diuretics
5. 腎でのマグネシウム処理における利尿剤の有効性 effect of diuretics on magnesium handling by the kidney

English Journal

Mini-review: regulation of the renal NaCl cotransporter by hormones.

Rojas-Vega L1, Gamba G2.
American journal of physiology. Renal physiology.Am J Physiol Renal Physiol.2016 Jan 1;310(1):F10-4. doi: 10.1152/ajprenal.00354.2015. Epub 2015 Oct 28.
The renal thiazide-sensitive NaCl cotransporter, NCC, is the major pathway for salt reabsorption in the distal convoluted tubule. The activity of this cotransporter is critical for regulation of several physiological variables such as blood pressure, serum potassium, acid base metabolism, and urinar
PMID 26511649

SGLT2 Inhibitors: Glucotoxicity and Tumorigenesis Downstream the Renal Proximal Tubule?

Bertinat R1, Nualart F1, Yáñez AJ1,2.
Journal of cellular physiology.J Cell Physiol.2015 Dec 11. doi: 10.1002/jcp.25286. [Epub ahead of print]
At present, diabetes mellitus is the main cause of end-stage renal disease. Effective glycaemic management is the most powerful tool to delay the establishment of diabetic complications, such as diabetic kidney disease. Together with reducing blood glucose levels, new anti-diabetic agents are expect
PMID 26661279

Luminal Angiotensin II Stimulates Rat Medullary Thick Ascending Limb Chloride Transport in the in the Presence of Basolateral Norepinephrine.

Baum M1.
American journal of physiology. Renal physiology.Am J Physiol Renal Physiol.2015 Dec 9:ajprenal.00447.2015. doi: 10.1152/ajprenal.00447.2015. [Epub ahead of print]
Angiotensin II is secreted by the proximal tubule resulting in luminal concentrations that are 100-1000 fold greater than that in the blood. Luminal angiotensin II has been shown to stimulate transport in the proximal tubule and in the distal nephron. Surprisingly, luminal angiotensin II inhibits Na
PMID 26661654

Japanese Journal

Obstructive nephropathy induced with DL-potassium hydrogen tartrate in F344 rats

Journal of Toxicologic Pathology 28(2), 89-97, 2015
NAID 130005072419

Obstructive nephropathy induced with DL-potassium hydrogen tartrate in F344 rats

Journal of Toxicologic Pathology advpub(0), 89-97, 2015
NAID 130004842623

Gitelman's Syndrome with Vomiting Manifested by Severe Metabolic Alkalosis and Progressive Renal Insufficiency

The Tohoku Journal of Experimental Medicine 231(3), 165-169, 2013
NAID 130004460092

「遠位尿細管」

Distal convoluted tubule
	Kidney nephron ("1st proximal convoluted tubule", "2nd distal convoluted tubule")
	Section of cortex of human kidney.
Details
Latin	tubulus contortus distalis
Precursor	Metanephrogenic blastema
Identifiers
Gray's	p.1223
MeSH	Distal+Kidney+Tubule
Dorlands; /Elsevier	12830066
FMA	17721
	Anatomical terminology