Linked Life Data

2107758

Source:http://linkedlifedata.com/resource/pubmed/id/2107758

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3 Pt 2
pubmed:dateCreated
1990-4-23
pubmed:abstractText
The vasopressin-dependent urea permeability of the rat terminal inner medullary collecting duct (IMCD) is much greater than can be explained by lipid-phase permeation or paracellular diffusion, suggesting the presence of vasopressin-stimulated facilitated transport pathway. We used the isolated perfused tubule technique to test whether the urea transport pathway exhibits saturation characteristics consistent with a facilitated pathway. When the luminal urea concentration was varied between 0 and 800 mM (no urea in peritubular bath), the relationship between the urea flux and the luminal concentration was linear with a y-axis intercept that was not significantly different from zero, indicating an absence of saturation in this concentration range. Higher concentrations of urea could not be tested due to technical limitations. However, when thiourea (a urea analogue that shares the urea transport pathway with urea) was substituted for urea in similar experiments, the apparent thiourea permeability fell with increasing thiourea concentration in the range 10-200 mM, indicative of saturation of the urea-thiourea transporter. When the urea concentration was varied in both bath and lumen, the lumen-to-bath urea flux approached a limiting value at 400-500 mM urea, consistent with saturation of the transporter. However, nonspecific inhibition of urea transport by bath urea could not be ruled out in those experiments. We conclude that the urea and thiourea transport pathway in the terminal IMCD exhibits saturation characteristics. However, the urea concentration required to saturate the pathway is apparently high, at least 400-500 mM in one set of experiments and probably greater than 800 mM in another.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0002-9513
pubmed:author
pubmed:issnType
Print
pubmed:volume
258
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
F486-94
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Concentration dependence of urea and thiourea transport in rat inner medullary collecting duct.
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, Research Support, Non-U.S. Gov't