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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
3
|
| pubmed:dateCreated |
1987-11-23
|
| pubmed:abstractText |
Experiments with large unilamellar dioleoylphosphatidylcholine vesicles were carried out in order to study the effect of membrane potential on the fluorescence of Oxonol VI. A partition equilibrium of dye between membrane and water was found to exist with a partition coefficient gamma identical to c lipid/c water of about 19,000 (at zero voltage). In the presence of an inside-positive membrane potential, the negatively charged dye accumulates in the intravesicular aqueous space according to a Nernst equilibrium. This leads to an increased adsorption of dye to the inner lipid monolayer and to a concomitant increase of fluorescence. The fluorescence change can be calibrated as a function of transmembrane voltage by generating a potassium diffusion potential in the presence of valinomycin. The intrinsic fluorescence of the membrane-bound dye is not affected by voltage; the whole influence of voltage on the fluorescence results from voltage-dependent partitioning of the dye between water and membrane. The voltage dependence of the apparent partition coefficient can be quantitatively described by a three-capacitor model in which the dye is assumed to bind to adsorption planes located on the hydrocarbon side of the membrane/solution interface. Oxonol VI was found to be suitable for detecting changes of membrane potential associated with the activity of the (Na+ + K+)-ATPase in reconstituted vesicles. When ATP is added to the external medium, pump molecules with the ATP-binding side facing outward become activated; this results in a translocation of net positive charge towards the vesicle interior. Under this condition, fluorescence changes corresponding to (inside-positive) potentials of up to 150-200 mV are observed. After the build-up of the membrane potential, a quasi-stationary state is reached in which the pump current is compensated by a back-flow of charge through passive conductance pathways.
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| pubmed:language |
eng
|
| pubmed:journal | |
| pubmed:citationSubset |
IM
|
| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/1,2-oleoylphosphatidylcholine,
http://linkedlifedata.com/resource/pubmed/chemical/Fluorescent Dyes,
http://linkedlifedata.com/resource/pubmed/chemical/Indicators and Reagents,
http://linkedlifedata.com/resource/pubmed/chemical/Ion Channels,
http://linkedlifedata.com/resource/pubmed/chemical/Isoxazoles,
http://linkedlifedata.com/resource/pubmed/chemical/Liposomes,
http://linkedlifedata.com/resource/pubmed/chemical/Oxazoles,
http://linkedlifedata.com/resource/pubmed/chemical/Phosphatidylcholines,
http://linkedlifedata.com/resource/pubmed/chemical/Potassium,
http://linkedlifedata.com/resource/pubmed/chemical/Sodium,
http://linkedlifedata.com/resource/pubmed/chemical/Sodium-Potassium-Exchanging ATPase,
http://linkedlifedata.com/resource/pubmed/chemical/Solutions,
http://linkedlifedata.com/resource/pubmed/chemical/Valinomycin,
http://linkedlifedata.com/resource/pubmed/chemical/oxonol VI
|
| pubmed:status |
MEDLINE
|
| pubmed:month |
Oct
|
| pubmed:issn |
0006-3002
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| pubmed:author | |
| pubmed:issnType |
Print
|
| pubmed:day |
16
|
| pubmed:volume |
903
|
| pubmed:owner |
NLM
|
| pubmed:authorsComplete |
Y
|
| pubmed:pagination |
480-94
|
| pubmed:dateRevised |
2007-11-15
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| pubmed:meshHeading |
pubmed-meshheading:2444259-Adsorption,
pubmed-meshheading:2444259-Diffusion,
pubmed-meshheading:2444259-Fluorescence,
pubmed-meshheading:2444259-Fluorescent Dyes,
pubmed-meshheading:2444259-Indicators and Reagents,
pubmed-meshheading:2444259-Ion Channels,
pubmed-meshheading:2444259-Isoxazoles,
pubmed-meshheading:2444259-Liposomes,
pubmed-meshheading:2444259-Membrane Potentials,
pubmed-meshheading:2444259-Oxazoles,
pubmed-meshheading:2444259-Phosphatidylcholines,
pubmed-meshheading:2444259-Potassium,
pubmed-meshheading:2444259-Sodium,
pubmed-meshheading:2444259-Sodium-Potassium-Exchanging ATPase,
pubmed-meshheading:2444259-Solutions,
pubmed-meshheading:2444259-Spectrometry, Fluorescence,
pubmed-meshheading:2444259-Spectrophotometry,
pubmed-meshheading:2444259-Valinomycin
|
| pubmed:year |
1987
|
| pubmed:articleTitle |
Oxonol VI as an optical indicator for membrane potentials in lipid vesicles.
|
| pubmed:affiliation |
Department of Biology, University of Konstanz, F.R.G.
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| pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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