Linked Life Data

9848774

Source:http://linkedlifedata.com/resource/pubmed/id/9848774

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
12
pubmed:dateCreated
1999-4-19
pubmed:abstractText
Erythrocyte Na+-Li+ countertransport shows an increased activity in essential hypertension and diabetic nephropathy, but its nature remains unknown. This amiloride-insensitive membrane transport may not be a mode of operation of the amiloride-sensitive NHE1, the only Na+-H+ exchange isoform found in human erythrocytes. Whether an independent, although unknown, amiloride-insensitive isoform mediates Na+-Li+ countertransport is unclear. Na+-H+ exchange activity was measured in acid-loaded erythrocytes. Dimethylamiloride, a specific inhibitor of Na+-H+ exchange and phloretin, a known inhibitor of Na+-Li+ countertransport, gave a reduction in H+-driven Na+ influx (by 31 and 37%, respectively). This effect was additive, and a 66% reduction in H+-driven Na+ influx was found in the presence of both inhibitors. Internal acidification, a stimulus for Na+-H+ exchange, enhanced Na+-Li+ countertransport activity (from 287 +/- 55 to 1213 +/- 165 micromol x Lcell(-1) h(-1), mean +/- SEM, P = 0.003). This transport remained sensitive to phloretin under both conditions. Conversely, external acidification decreased Na+-Li+ countertransport activity (as expected for a Na+-H+ exchanger). Competition between internal H+ and Li+ or Na+ for a common binding site was present. Finally, similar kinetic parameters for external Na+ characterized Na+-Li+ countertransport and the phloretin-sensitive component of H+-driven Na+ influx. These findings suggest that both Na+-Li+ countertransport and the amiloride-insensitive, phloretin-sensitive component of H+-driven Na+ influx can be mediated by a previously unrecognized novel amiloride-insensitive Na+-H+ exchange isoform in human erythrocytes.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
1046-6673
pubmed:author
pubmed:issnType
Print
pubmed:volume
9
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
2203-11
pubmed:dateRevised
2004-11-17
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Amiloride-insensitive Na+-H+ exchange: a candidate mediator of erythrocyte Na+-Li+ countertransport.
pubmed:affiliation
Division of Medicine, Scientific Institute San Raffaele, University of Milan, Italy.
pubmed:publicationType
Journal Article