Electrokinetic measurements of membrane capacitance and conductance for pancreatic β-cells
Jakubek, L. M.
Sanger, R. H.
Corson, Erica D.
Smith, Peter J. S.
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KeywordElectrokinetic measurements; Membrane capacitance; Pancreatic beta-cells; Membrane conductance; Insulin secreting cells; Insulinoma cells; Dielectrophoresis; Electrorotation; Mammalian cells; Ion channels; Membrane surface conductance; Whole-cell patch-clamp technique; Passive conduction; Membrane pores; Electric field stresses; Dielectrophoresis experiments
Membrane capacitance and membrane conductance values are reported for insulin secreting cells (primary β-cells and INS-1 insulinoma cells) determined using the methods of dielectrophoresis and electrorotation. The membrane capacitance value of 12.57 (± 1.46) mF/m2 obtained for β-cells, and the values 9.96 (± 1.89) mF/m2 to 10.65 (± 2.1) mF/m2 obtained for INS-1 cells, fall within the range expected for mammalian cells. The electrorotation results for the INS-1 cells lead to a value of 36 (± 22) S/m2 for the membrane conductance associated with ion channels, if values in the range 2nS to 3 nS are assumed for the membrane surface conductance. This membrane conductance value falls within the range reported for INS cells obtained using the whole-cell patch-clamp technique. However, the total ‘effective’ membrane conductance value of 601 (± 182) S/m2 obtained for the INS-1 cells by dielectrophoresis is significantly larger (by a factor of around three-fold) than the values obtained by electrorotation. This could result from an increased membrane surface conductance, or increased passive conduction of ions through membrane pores, induced by the larger electric field stresses experienced by cells in the dielectrophoresis experiments.
Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of IEE for personal use, not for redistribution. The definitive version was published in IEE Proceedings - Nanobiotechnology 152 (2005): 189-193, doi:10.1049/ip-nbt:20050040.
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