These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: A combined patch-clamp and electrorotation study of the voltage- and frequency-dependent membrane capacitance caused by structurally dissimilar lipophilic anions.
    Author: Zimmermann D, Kiesel M, Terpitz U, Zhou A, Reuss R, Kraus J, Schenk WA, Bamberg E, Sukhorukov VL.
    Journal: J Membr Biol; 2008 Jan; 221(2):107-21. PubMed ID: 18197354.
    Abstract:
    Interactions of structurally dissimilar anionic compounds with the plasma membrane of HEK293 cells were analyzed by patch clamp and electrorotation. The combined approach provides complementary information on the lipophilicity, preferential affinity of the anions to the inner/outer membrane leaflet, adsorption depth and transmembrane mobility. The anionic species studied here included the well-known lipophilic anions dipicrylamine (DPA(-)), tetraphenylborate (TPB(-)) and [W(2)(CO)(10)(S(2)CH)](-), the putative lipophilic anion B(CF(3))(4)(-) and three new heterocyclic W(CO)(5) derivatives. All tested anions partitioned strongly into the cell membrane, as indicated by the capacitance increase in patch-clamped cells. The capacitance increment exhibited a bell-shaped dependence on membrane voltage. The midpoint potentials of the maximum capacitance increment were negative, indicating the exclusion of lipophilic anions from the outer membrane leaflet. The adsorption depth of the large organic anions DPA(-), TPB(-) and B(CF(3))(4)(-) increased and that of W(CO)(5) derivatives decreased with increasing concentration of mobile charges. In agreement with the patch-clamp data, electrorotation of cells treated with DPA(-) and W(CO)(5) derivatives revealed a large dispersion of membrane capacitance in the kilohertz to megahertz range due to the translocation of mobile charges. In contrast, in the presence of TPB(-) and B(CF(3))(4)(-) no mobile charges could be detected by electrorotation, despite their strong membrane adsorption. Our data suggest that the presence of oxygen atoms in the outer molecular shell is an important factor for the fast translocation ability of lipophilic anions.
    [Abstract] [Full Text] [Related] [New Search]