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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
4
|
| pubmed:dateCreated |
1993-11-12
|
| pubmed:abstractText |
The epithelia of the medullary thick ascending limb (MAL) consists of two cell types, high (HBC) and low basolateral conductance (LBC) cell, depending on the K+ conductance of the basolateral membrane. The NH4+ conductance distinct from the K+ conductance has been suggested to exist in the proximal tubule, MAL cell, and Xenopus oocyte. The present study was designed to examine whether there is a conductive NH4+ transport system distinct from K+ conductance in two different cell types of the hamster MAL perfused in vitro. The basolateral membrane voltage (VB) was measured by impaling cells with conventional microelectrodes. Addition of NH4+ to the bath depolarized VB in a dose-dependent manner in both cell types. The response was maintained in the absence of HCO3-. When the VB deflection elicited upon 50 mM KCl or NH4Cl in the bath (delta VBK+ or delta VBNH4+) were compared, delta VBNH4+ was almost the same as delta VBK+ in the HBC cell, whereas the former was greater than the latter in the LBC. In the HBC cell, 10 mM Ba2+ in the bath equally suppressed both delta VBK+ and delta VBNH4+, whereas in the LBC cell it suppressed delta VBK+ with a small effect on delta VBNH4+, indicating that NH4+ is transported via a pathway distinct from Ba(2+)-sensitive K+ conductance. The VB deflection by NH4+ was unaffected by addition of 0.1 mM ouabain or 10 microM 5-nitro-2-(3-phenylpropylamino)-benzoate (a Cl- channel blocker) to the bath, excluding the contribution of the Na+, K+ pump or Cl- channel. An abrupt reduction of Na+ in the bath from 200 to 20 mM did not cause any changes in VB, suggesting that a nonselective cation channel may not account for the NH4+ transport. Amiloride at 10 microM inhibited delta VBNH4+ with a higher efficacy in the LBC cell. We conclude that a rheogenic NH4+ transport system independent from the K+ conductance exists in the basolateral membrane of the LBC cell of the hamster MAL, and may play some roles in the regulation of NH4+ transport.
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| pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-1327152,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-1330183,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-1372714,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-1762309,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-1890804,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-2156445,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-2315005,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-2409564,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-2434915,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-2439987,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-2725680,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-2839547,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-3134821,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-3394813,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-3560204,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-3885755,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-3953823,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-5923067,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8408639-6742203
|
| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
AIM
|
| pubmed:chemical | |
| pubmed:status |
MEDLINE
|
| pubmed:month |
Oct
|
| pubmed:issn |
0021-9738
|
| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:volume |
92
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
1881-8
|
| pubmed:dateRevised |
2009-11-18
|
| pubmed:meshHeading |
pubmed-meshheading:8408639-Ammonia,
pubmed-meshheading:8408639-Animals,
pubmed-meshheading:8408639-Bicarbonates,
pubmed-meshheading:8408639-Biological Transport,
pubmed-meshheading:8408639-Cell Membrane,
pubmed-meshheading:8408639-Cricetinae,
pubmed-meshheading:8408639-Female,
pubmed-meshheading:8408639-Kidney Medulla,
pubmed-meshheading:8408639-Kinetics,
pubmed-meshheading:8408639-Loop of Henle,
pubmed-meshheading:8408639-Male,
pubmed-meshheading:8408639-Membrane Potentials,
pubmed-meshheading:8408639-Mesocricetus,
pubmed-meshheading:8408639-Potassium
|
| pubmed:year |
1993
|
| pubmed:articleTitle |
Cellular heterogeneity of ammonium ion transport across the basolateral membrane of the hamster medullary thick ascending limb of Henle's loop.
|
| pubmed:affiliation |
Department of Pharmacology, Jichi Medical School, Tochigi, Japan.
|
| pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, Non-U.S. Gov't
|