The Extracellular Electrical Resistivity in Cell Adhesion

• Published in: Biophysical journal 2006-04, Vol.90 (7), p.2600-2611
• Main Authors: Gleixner, Raimund, Fromherz, Peter
• Format: Article
• Language: English
• Subjects: Animals; Biophysics; Cell Adhesion; Cell adhesion & migration; Cell Biophysics; Cell Communication; Cell Line; Cell Membrane - metabolism; Cytoplasm - metabolism; Dielectric properties; Electric Conductivity; Electric Impedance; Electrochemistry - methods; Electrolytes - chemistry; Electrophysiology - methods; Extracellular Matrix - metabolism; Extracellular Space; Fibronectins - chemistry; Fourier Analysis; Humans; Intercellular Junctions; Membrane Potentials; Microscopy, Fluorescence; Neurons - metabolism; Polylysine - chemistry; Proteins; Rats; Silicon - chemistry; Time Factors; Tissues
• ISSN: 0006-3495; 1542-0086
• DOI: 10.1529/biophysj.105.072587

The interaction of cells in a tissue depends on the nature of the extracellular matrix. The electrical properties of the narrow extracellular space are unknown. Here we consider cell adhesion mediated by extracellular matrix protein on a solid substrate as a model system. We culture human embryonic kidney (HEK293) cells on silica coated with fibronectin and determine the electrical resistivity in the cell-solid junction ρ J = r J d J by combining measurements of the sheet resistance r J and of the distance d J between membrane and substrate. The sheet resistance is obtained from phase fluorometry of the voltage-sensitive dye ANNINE-5 by alternating-current stimulation from the substrate. The distance is measured by fluorescence interference contrast microscopy. We change the resistivity of the bath in a range from 66 ⁡ Ω ⁡ cm to 750 ⁡ Ω ⁡ cm and find that the sheet resistance r J is proportionally enhanced, but that the distance is invariant around d J = 75 ⁡ nm . In all cases, the resulting resistivity ρ J is indistinguishable from the resistivity of the bath. A similar result is obtained for rat neurons cultured on polylysine. On that basis, we propose a “bulk resistivity in cell adhesion” model for cell-solid junctions. The observations suggest that the electrical interaction between cells in a tissue is determined by an extracellular space with the electrical properties of bulk electrolyte.