Document Detail


Renal medullary microcirculation: architecture and exchange.
MedLine Citation:
PMID:  7497165     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The architecture of the renal medullary microcirculation is highly specialized. Consistent with their role in countercurrent exchange, the vessels (the vasa recta and the intervening capillaries) have high permeabilities to fluid and small hydrophilic solutes. The urea permeability of the continuous endothelium of the descending vasa recta (DVR) in the outer medulla is greatly enhanced by a urea transporter. Aquaporin channels have also been identified in these vessels. In spite of the absence of lymphatics from the inner medulla, fluid uptake from the interstitial fluid (ISF) through the fenestrated endothelium of the ascending vasa recta (AVR) appears to be driven by differences in hydrostatic and oncotic pressure. Because the AVR have high Lp's [10(-5) cm s-1 (cm H2O)-1] and are mechanically linked to surrounding structures, small increments of ISF pressures above the pressure within the AVR can drive significant volumes of fluid into AVR if ISF volume expands. The lower reflection coefficients to serum albumin of the AVR as compared with the DVR may be important in the clearance of interstitial plasma protein. Recent work on isolated DVR from the outer medulla has revealed that these vessels are capable of vasoconstriction and thus of regulating medullary blood flow.
Authors:
C C Michel
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Review    
Journal Detail:
Title:  Microcirculation (New York, N.Y. : 1994)     Volume:  2     ISSN:  1073-9688     ISO Abbreviation:  Microcirculation     Publication Date:  1995 Aug 
Date Detail:
Created Date:  1996-01-18     Completed Date:  1996-01-18     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9434935     Medline TA:  Microcirculation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  125-39     Citation Subset:  IM    
Affiliation:
Department of Physiology and Biophysics, St. Mary's Hospital Medical School, Imperial College of Science, Technology and Medicine, London, U.K.
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MeSH Terms
Descriptor/Qualifier:
Animals
Biological Transport
Blood Flow Velocity
Body Water / metabolism
Capillary Permeability
Kidney Medulla / blood supply*
Metabolic Clearance Rate
Microcirculation / ultrastructure
Renal Circulation / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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