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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2 Pt 2
pubmed:dateCreated
1993-4-6
pubmed:abstractText
We measured the urea and NaCl permeabilities (Purea and PNaCl, respectively) of the following nephron segments from chinchilla: the upper part of the long-loop descending limb (from outer medulla, LDLu), the middle part of the long-loop descending limb (from outer 30% of the inner medulla, LDLm), the lower part of the long-loop descending limb (from deep inner medulla, LDLl), and the thin ascending limb (from deep inner medulla, ATL). We found that Purea (x10(-5) cm/s) was relatively low in the LDLu (3.3), but that the value was larger in the inner medullary thin descending limb (16.8 for LDLm and 47.6 for LDLl). The ATL had an even higher value (170). Phloretin, 0.25 mM, added to the peritubular bath had no effect on Purea of these segments, suggesting that the rapid transport rate is not due to a phloretin-sensitive facilitated transport pathway like that seen in the inner medullary collecting duct. PNaCl (x10(-5) cm/s) also increased with distance along the length of the thin descending limb (LDLu, 11.7; LDLm, 41.2; LDLl, 98.4; and ATL, 321). Calculations from NaCl dilution potential measurements showed that LDLu was Na+ permselective, whereas LDLl and ATL were Cl- permselective. High solute permeabilities in the inner medullary thin descending limb contradict a major requirement of the passive model of urinary concentration developed previously (J. P. Kokko and F. C. Rector, Jr. Kidney Int. 2: 214-223, 1972; and J. L. Stephenson. Kidney Int. 2: 85-94, 1972).
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0002-9513
pubmed:author
pubmed:issnType
Print
pubmed:volume
264
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
F337-43
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
In vitro perfusion of chinchilla thin limb segments: urea and NaCl permeabilities.
pubmed:affiliation
Laboratory of Kidney and Electrolyte Metabolism, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892.
pubmed:publicationType
Journal Article, Comparative Study, In Vitro