Effects of medium amino acids on ouabain-sensitive 86Rb+ -uptake and membrane-potential dependent [3H]tetraphenylphosphonium accumulation in Friend erythroleukemia cells.
Eur J Cell Biol
; 46(3): 453-7, 1988 Aug.
Article
em En
| MEDLINE
| ID: mdl-3181165
ABSTRACT
The effects of amino acids present in minimal essential medium were investigated on 86Rb+ -fluxes and on the membrane-potential dependent accumulation of the lipophilic cation [3H]tetraphenylphosphonium (TTP+) in logarithmically growing Friend erythroleukemia cells. The ouabain-sensitive 86Rb+ -uptake measured as well in complete growth medium as in Earle's balanced salt solution (EBSS) with amino acid composition present in growth medium, was 3 to 4-fold increased in comparison to the 86Rb+-uptake measured in pure EBSS only. The Na+,K+,2Cl- -cotransport measured as piretanide-sensitive 86Rb+-uptake was reduced in the presence of amino acids. Stimulation of the ouabain-sensitive 86Rb+ -uptake could be brought about by the addition of alanine alone or of the sodium ionophore monensin. In spite of the activation of the Na+,K+ -pump the membrane-potential dependent accumulation of [3H]TPP+ was about 40 per cent reduced in the presence of medium amino acids indicating a decreased membrane potential under these conditions. On the other hand, monensin which induces an electrically silent Na+ -influx via Na+/H+ -exchange was shown to hyperpolarize the membrane on the basis of [3H]TPP+-accumulation. These results suggest that the intensive uptake of neutral amino acids by Na+-cotransport in rapidly growing cells may be responsible for both stimulation of the Na+,K+ -pump and decrease in the transmembrane potential.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Oniocompostos
/
Compostos Organofosforados
/
Ouabaína
/
Radioisótopos de Rubídio
/
Células Tumorais Cultivadas
/
Aminoácidos
Tipo de estudo:
Diagnostic_studies
Limite:
Humans
Idioma:
En
Revista:
Eur J Cell Biol
Ano de publicação:
1988
Tipo de documento:
Article