Architecture of the human renal inner medulla and functional implications

Guojun Wei, Seymour Rosen, William H Dantzler, Thomas L Pannabecker

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The architecture of the inner stripe of the outer medulla of the human kidney has long been known to exhibit distinctive configurations; however, inner medullary architecture remains poorly defined. Using immunohistochemistry with segment-specific antibodies for membrane fluid and solute transporters and other proteins, we identified a number of distinctive functional features of human inner medulla. In the outer inner medulla, aquaporin-1 (AQP1)-positive long-loop descending thin limbs (DTLs) lie alongside descending and ascending vasa recta (DVR, AVR) within vascular bundles. These vascular bundles are continuations of outer medullary vascular bundles. Bundles containing DTLs and vasa recta lie at the margins of coalescing collecting duct (CD) clusters, thereby forming two regions, the vascular bundle region and the CD cluster region. Although AQP1 and urea transporter UT-B are abundantly expressed in long-loop DTLs and DVR, respectively, their expression declines with depth below the outer medulla. Transcellular water and urea fluxes likely decline in these segments at progressively deeper levels. Smooth muscle myosin heavy chain protein is also expressed in DVR of the inner stripe and the upper inner medulla, but is sparsely expressed at deeper inner medullary levels. In rodent inner medulla, fenestrated capillaries abut CDs along their entire length, paralleling ascending thin limbs (ATLs), forming distinct compartments (interstitial nodal spaces; INSs); however, in humans this architecture rarely occurs. Thus INSs are relatively infrequent in the human inner medulla, unlike in the rodent where they are abundant. UT-B is expressed within the papillary epithelium of the lower inner medulla, indicating a transcellular pathway for urea across this epithelium.

Original languageEnglish (US)
Pages (from-to)F627-F637
JournalAmerican Journal of Physiology - Renal Physiology
Volume309
Issue number7
DOIs
StatePublished - Sep 1 2015

Fingerprint

Blood Vessels
Extremities
Aquaporin 1
Kidney
Rectum
Urea
Rodentia
Epithelium
Kidney Medulla
Smooth Muscle Myosins
Transcytosis
Myosin Heavy Chains
Proteins
Immunohistochemistry
Membranes
Water
Antibodies

Keywords

  • Aquaporin-1
  • Aquaporin-2
  • Blood flow
  • Hemodynamics
  • Urine concentrating mechanism
  • UT-B

ASJC Scopus subject areas

  • Physiology
  • Urology

Cite this

Architecture of the human renal inner medulla and functional implications. / Wei, Guojun; Rosen, Seymour; Dantzler, William H; Pannabecker, Thomas L.

In: American Journal of Physiology - Renal Physiology, Vol. 309, No. 7, 01.09.2015, p. F627-F637.

Research output: Contribution to journalArticle

@article{a1b050f64af1476898bc5157072b49eb,
title = "Architecture of the human renal inner medulla and functional implications",
abstract = "The architecture of the inner stripe of the outer medulla of the human kidney has long been known to exhibit distinctive configurations; however, inner medullary architecture remains poorly defined. Using immunohistochemistry with segment-specific antibodies for membrane fluid and solute transporters and other proteins, we identified a number of distinctive functional features of human inner medulla. In the outer inner medulla, aquaporin-1 (AQP1)-positive long-loop descending thin limbs (DTLs) lie alongside descending and ascending vasa recta (DVR, AVR) within vascular bundles. These vascular bundles are continuations of outer medullary vascular bundles. Bundles containing DTLs and vasa recta lie at the margins of coalescing collecting duct (CD) clusters, thereby forming two regions, the vascular bundle region and the CD cluster region. Although AQP1 and urea transporter UT-B are abundantly expressed in long-loop DTLs and DVR, respectively, their expression declines with depth below the outer medulla. Transcellular water and urea fluxes likely decline in these segments at progressively deeper levels. Smooth muscle myosin heavy chain protein is also expressed in DVR of the inner stripe and the upper inner medulla, but is sparsely expressed at deeper inner medullary levels. In rodent inner medulla, fenestrated capillaries abut CDs along their entire length, paralleling ascending thin limbs (ATLs), forming distinct compartments (interstitial nodal spaces; INSs); however, in humans this architecture rarely occurs. Thus INSs are relatively infrequent in the human inner medulla, unlike in the rodent where they are abundant. UT-B is expressed within the papillary epithelium of the lower inner medulla, indicating a transcellular pathway for urea across this epithelium.",
keywords = "Aquaporin-1, Aquaporin-2, Blood flow, Hemodynamics, Urine concentrating mechanism, UT-B",
author = "Guojun Wei and Seymour Rosen and Dantzler, {William H} and Pannabecker, {Thomas L}",
year = "2015",
month = "9",
day = "1",
doi = "10.1152/ajprenal.00236.2015",
language = "English (US)",
volume = "309",
pages = "F627--F637",
journal = "American Journal of Physiology",
issn = "0363-6143",
publisher = "American Physiological Society",
number = "7",

}

TY - JOUR

T1 - Architecture of the human renal inner medulla and functional implications

AU - Wei, Guojun

AU - Rosen, Seymour

AU - Dantzler, William H

AU - Pannabecker, Thomas L

PY - 2015/9/1

Y1 - 2015/9/1

N2 - The architecture of the inner stripe of the outer medulla of the human kidney has long been known to exhibit distinctive configurations; however, inner medullary architecture remains poorly defined. Using immunohistochemistry with segment-specific antibodies for membrane fluid and solute transporters and other proteins, we identified a number of distinctive functional features of human inner medulla. In the outer inner medulla, aquaporin-1 (AQP1)-positive long-loop descending thin limbs (DTLs) lie alongside descending and ascending vasa recta (DVR, AVR) within vascular bundles. These vascular bundles are continuations of outer medullary vascular bundles. Bundles containing DTLs and vasa recta lie at the margins of coalescing collecting duct (CD) clusters, thereby forming two regions, the vascular bundle region and the CD cluster region. Although AQP1 and urea transporter UT-B are abundantly expressed in long-loop DTLs and DVR, respectively, their expression declines with depth below the outer medulla. Transcellular water and urea fluxes likely decline in these segments at progressively deeper levels. Smooth muscle myosin heavy chain protein is also expressed in DVR of the inner stripe and the upper inner medulla, but is sparsely expressed at deeper inner medullary levels. In rodent inner medulla, fenestrated capillaries abut CDs along their entire length, paralleling ascending thin limbs (ATLs), forming distinct compartments (interstitial nodal spaces; INSs); however, in humans this architecture rarely occurs. Thus INSs are relatively infrequent in the human inner medulla, unlike in the rodent where they are abundant. UT-B is expressed within the papillary epithelium of the lower inner medulla, indicating a transcellular pathway for urea across this epithelium.

AB - The architecture of the inner stripe of the outer medulla of the human kidney has long been known to exhibit distinctive configurations; however, inner medullary architecture remains poorly defined. Using immunohistochemistry with segment-specific antibodies for membrane fluid and solute transporters and other proteins, we identified a number of distinctive functional features of human inner medulla. In the outer inner medulla, aquaporin-1 (AQP1)-positive long-loop descending thin limbs (DTLs) lie alongside descending and ascending vasa recta (DVR, AVR) within vascular bundles. These vascular bundles are continuations of outer medullary vascular bundles. Bundles containing DTLs and vasa recta lie at the margins of coalescing collecting duct (CD) clusters, thereby forming two regions, the vascular bundle region and the CD cluster region. Although AQP1 and urea transporter UT-B are abundantly expressed in long-loop DTLs and DVR, respectively, their expression declines with depth below the outer medulla. Transcellular water and urea fluxes likely decline in these segments at progressively deeper levels. Smooth muscle myosin heavy chain protein is also expressed in DVR of the inner stripe and the upper inner medulla, but is sparsely expressed at deeper inner medullary levels. In rodent inner medulla, fenestrated capillaries abut CDs along their entire length, paralleling ascending thin limbs (ATLs), forming distinct compartments (interstitial nodal spaces; INSs); however, in humans this architecture rarely occurs. Thus INSs are relatively infrequent in the human inner medulla, unlike in the rodent where they are abundant. UT-B is expressed within the papillary epithelium of the lower inner medulla, indicating a transcellular pathway for urea across this epithelium.

KW - Aquaporin-1

KW - Aquaporin-2

KW - Blood flow

KW - Hemodynamics

KW - Urine concentrating mechanism

KW - UT-B

UR - http://www.scopus.com/inward/record.url?scp=84943327662&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84943327662&partnerID=8YFLogxK

U2 - 10.1152/ajprenal.00236.2015

DO - 10.1152/ajprenal.00236.2015

M3 - Article

C2 - 26290371

AN - SCOPUS:84943327662

VL - 309

SP - F627-F637

JO - American Journal of Physiology

JF - American Journal of Physiology

SN - 0363-6143

IS - 7

ER -