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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
11
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pubmed:dateCreated |
1983-7-15
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pubmed:abstractText |
We examined the effects of external H+ on the kinetics of Na+-H+ exchange in microvillus membrane vesicles isolated from the rabbit renal cortex. The initial rate of Na+ influx into vesicles with internal pH 6.0 was optimal at external pH 8.5 and was progressively inhibited as external pH was reduced to 6.0. A plot of 1/V versus [H+]o was linear and yielded apparent KH = 35 nM (apparent pK 7.5). In vesicles with internal pH 6.0 studied at external pH 7.5 or 6.6, apparent KNa was 13 or 54 mM, Ki for inhibition of Na+ influx by external Li+ was 1.2 or 5.2 mM, Ki for inhibition by external NH4+ was 11 or 50 mM, and Ki for inhibition by external amiloride was 7 or 25 microM, respectively. These findings were consistent with competition between each cation and H+ at a site with apparent pK 7.3-7.5. Lastly, stimulation of 22Na efflux by external Na+ (i.e. Na+-Na+ exchange) was inhibited as external pH was reduced from 7.5 to 6.0, also consistent with competition between external H+ and external Na+. Thus, in contrast with internal H+, which interacts at both transport and activator sites, external H+ interacts with the renal microvillus membrane Na+-H+ exchanger at a single site, namely the external transport site, where H+, Na+, Li+, NH4+, and amiloride all compete for binding.
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Jun
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pubmed:issn |
0021-9258
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
10
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pubmed:volume |
258
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
6767-71
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:6304054-Amiloride,
pubmed-meshheading:6304054-Animals,
pubmed-meshheading:6304054-Carrier Proteins,
pubmed-meshheading:6304054-Cell Membrane,
pubmed-meshheading:6304054-Hydrogen-Ion Concentration,
pubmed-meshheading:6304054-Kidney Cortex,
pubmed-meshheading:6304054-Kinetics,
pubmed-meshheading:6304054-Microvilli,
pubmed-meshheading:6304054-Rabbits,
pubmed-meshheading:6304054-Sodium,
pubmed-meshheading:6304054-Sodium-Hydrogen Antiporter
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pubmed:year |
1983
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pubmed:articleTitle |
Interaction of external H+ with the Na+-H+ exchanger in renal microvillus membrane vesicles.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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