Linked Life Data

1637842

Source:http://linkedlifedata.com/resource/pubmed/id/1637842

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1992-8-31
pubmed:abstractText
Factors likely to modulate the ionic selectivity of monensin were examined on Enterococcus hirae (Streptococcus faecalis) in two states previously characterized: the resting (de-energized) cell and the active (energized) cell. Internal and external Na+ were followed by corresponding 23Na-NMR resonances K+ concentrations were measured by atomic absorption. For a given cellular population of de-energized cells, the apparent transport rates and the final cationic concentrations reached at the steady state were decreasing with the ionophore dose. Monensin was selective for sodium only at low concentrations, in the range 1 mM-10(-4) mM the transport was depending on the effective cationic gradients. Comparison of the activity curves for two cell populations (7.10(9) and 7.10(10) cells/ml) showed the importance of the ratios of monensin/mg phospholipid and also of the ratios of external/internal volumes. On energized cells, except for low monensin concentrations, the main effect was a K(+)-induced efflux and not a Na+ influx. Two factors were modulating the resulting selectivity of this ionophore: the response of the intrinsic bacterial carriers and the generation of the gradients (mainly the external pH) which were favourable to a K+/Na+ transport. Once again the results obtained for two cell populations could be compared, the determining factors were the ratio external/internal volume and the generation of the pH gradient.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jul
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
27
pubmed:volume
1108
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
177-82
pubmed:dateRevised
2003-11-14
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
Conditions modulating the ionic selectivity of transport by monensin examined on Enterococcus hirae (Streptococcus faecalis) by 23Na-NMR and K+ atomic absorption.
pubmed:affiliation
Laboratoire de Chimie Organique Biologique, U.R.A. 485 du CNRS. Université Blaise Pascal, Aubiere, France.
pubmed:publicationType
Journal Article