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Phloretin-induced changes of lipophilic ion transport across the plasma membrane of mammalian cells

 
: Sukhorukov, V.; Kürschner, M.; Dilky, S.; Lisec, T.; Wagner, B.; Schenk, W.A.; Benz, R.; Zimmermann, U.

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Biophysical journal 81 (2001), No.2, pp.1006-1013
ISSN: 0006-3495
ISSN: 1542-0086
English
Journal Article
Fraunhofer ISIT ()

Abstract
The adsorption of the hydrophobic anion [W(CO)(5)CN](-) to human lymphoid Jurkat cells gave rise to an additional anti-field peak in the rotational spectra of single cells, indicating that the cell membrane displayed a strong dielectric dispersion in the kilohertz to megahertz frequency range. The surface concentration of the adsorbed anion and its translocation rate constant between the two membrane boundaries could be evaluated from the rotation spectra of cells by applying the previously proposed mobile charge model. Similar single-cell electrorotation experiments were performed to examine the effect of phloretin, a dipolar molecule known to influence the dipole potential of membranes, on the transport of [W(CO)SCN]- across the plasma membrane of mammalian cells. The adsorption of [W(CO)5CN]- was significantly reduced by phloretin, which is in reasonable agreement with the known phloretin-induced effects on artificial and biological membranes. The IC50 for the effect of phloretin on the transport parameters of the lipophilic ion was similar to 10 muM. The results of this study are consistent with the assumption that the binding of phloretin reduces the intrinsic dipole potential of the plasma membrane. The experimental approach developed here allows the quantification of intrinsic dipole potential changes within the plasma membrane of living cells.

: http://publica.fraunhofer.de/documents/B-73524.html