Biophys J, August 2001, p. 1006-1013, Vol. 81, No. 2

Phloretin-Induced Changes of Lipophilic Ion Transport across the Plasma Membrane of Mammalian Cells

Vladimir L. Sukhorukov,^* Markus Kürschner,^* Stefan Dilsky,^* Thomas Lisec, Bernd Wagner, Wolfdieter A. Schenk,^* Roland Benz,^* and Ulrich Zimmermann^*

 ^*Lehrstuhl für Biotechnologie, Biozentrum, and Institut für Anorganische Chemie der Universität Würzburg, D-97074 Würzburg, Germany, and  Fraunhofer Institut Siliziumtechnologie, D-25524 Itzehoe, Germany

The adsorption of the hydrophobic anion [W(CO)₅CN] 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)₅CN] 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 ~10 µM. 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.

Biophys J, August 2001, p. 1006-1013, Vol. 81, No. 2
© 2001 by the Biophysical Society   0006-3495/01/08/1006/08  $2.00

This article has been cited by other articles:

				M. Kiesel, R. Reuss, J. Endter, D. Zimmermann, H. Zimmermann, R. Shirakashi, E. Bamberg, U. Zimmermann, and V. L. Sukhorukov Swelling-Activated Pathways in Human T-Lymphocytes Studied by Cell Volumetry and Electrorotation Biophys. J., June 15, 2006; 90(12): 4720 - 4729. [Abstract] [Full Text] [PDF]