Source:http://linkedlifedata.com/resource/pubmed/id/16580864
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
1-2
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| pubmed:dateCreated |
2006-4-24
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| pubmed:abstractText |
The recently cloned, non-erythrocyte Rh glycoproteins (Rhbg and Rhcg) are expressed in the intercalated cells of the renal collecting duct. The apical Rhcg and the basolateral Rhbg are likely involved in NH3 and/or NH4+ transport, yet the characteristics of this transport are not yet certain. In this study we investigated the mechanism of NH4+ transport by Rhbg and Rhcg expressed in Xenopus oocytes. We used a two-electrode voltage-clamp and ion-selective microelectrodes to measure NH4+-induced currents (I(NH4)) and changes in pHi, respectively. In oocytes expressing Rhcg, exposure to bath [NH4+] of 2.5-20 mM induced inward currents that were slightly more than those in H2O-injected (control) oocytes. I-V plots in the presence of NH4+ showed a small increase in slope conductance only at positive potentials. On the other hand, in oocytes expressing Rhbg, 5 mM NH4+ induced an inward I(NH4) of -79 nA, decreased pHi (DeltapHi) by 0.13 at a rate (dpHi/dt) of -2 7 x 10(-4) pH/s and depolarized the cell by 45 mV. These changes were significantly more than those in control oocytes. I-V plots in the presence of NH4+ showed substantial increase in conductance. Amiloride (1 mM) inhibited I(NH4), DeltapHi and dpHi/dt in oocytes expressing Rhbg but not in control oocytes. Raising bath [NH4+] in increments from 1 to 20 mM elicited a faster dpHi/dt, a larger decrease in pHi and a larger depolarization. Net NH4+ flux by Rhbg (estimated from dpHi/dt) was proportional to [NH4+] gradient and followed saturation kinetics with an apparent Km of 2.3 mM. Methyl ammonium (5 mM) induced a current of -63 nA in Rhbg oocytes but did not cause any change in control oocytes. These data indicate that: 1) Rhbg transport of NH4+ is electrogenic. 2) Methyl ammonium is transported by Rhbg. 3) NH4+ transport by Rhbg is saturated at high concentrations with Michaelis-Menten kinetics.
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:citationSubset |
IM
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| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Amiloride,
http://linkedlifedata.com/resource/pubmed/chemical/Ammonia,
http://linkedlifedata.com/resource/pubmed/chemical/Cation Transport Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Glycoproteins,
http://linkedlifedata.com/resource/pubmed/chemical/Membrane Glycoproteins,
http://linkedlifedata.com/resource/pubmed/chemical/Membrane Transport Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Methylamines,
http://linkedlifedata.com/resource/pubmed/chemical/Quaternary Ammonium Compounds,
http://linkedlifedata.com/resource/pubmed/chemical/Recombinant Fusion Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/RhBG protein, mouse,
http://linkedlifedata.com/resource/pubmed/chemical/Rhcg protein, mouse,
http://linkedlifedata.com/resource/pubmed/chemical/Sodium Channel Blockers,
http://linkedlifedata.com/resource/pubmed/chemical/methylamine
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| pubmed:status |
MEDLINE
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| pubmed:issn |
1246-7820
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:volume |
13
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
147-53
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| pubmed:meshHeading |
pubmed-meshheading:16580864-Amiloride,
pubmed-meshheading:16580864-Ammonia,
pubmed-meshheading:16580864-Animals,
pubmed-meshheading:16580864-Biological Transport,
pubmed-meshheading:16580864-Cation Transport Proteins,
pubmed-meshheading:16580864-Female,
pubmed-meshheading:16580864-Glycoproteins,
pubmed-meshheading:16580864-Hydrogen-Ion Concentration,
pubmed-meshheading:16580864-Ion Transport,
pubmed-meshheading:16580864-Kidney,
pubmed-meshheading:16580864-Kinetics,
pubmed-meshheading:16580864-Membrane Glycoproteins,
pubmed-meshheading:16580864-Membrane Transport Proteins,
pubmed-meshheading:16580864-Methylamines,
pubmed-meshheading:16580864-Mice,
pubmed-meshheading:16580864-Oocytes,
pubmed-meshheading:16580864-Osmolar Concentration,
pubmed-meshheading:16580864-Patch-Clamp Techniques,
pubmed-meshheading:16580864-Quaternary Ammonium Compounds,
pubmed-meshheading:16580864-Recombinant Fusion Proteins,
pubmed-meshheading:16580864-Sodium Channel Blockers,
pubmed-meshheading:16580864-Transfection,
pubmed-meshheading:16580864-Xenopus laevis
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| pubmed:articleTitle |
Electrogenic ammonium transport by renal Rhbg.
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| pubmed:affiliation |
Department of Medicine, Section of Nephrology, SL-45, Tulane University School of Medicine, 1430 Tulane Avenue, New Orleans, LA 70112, USA. nakhoul@tulane.edu
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| pubmed:publicationType |
Journal Article
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