title: The extracellular electrical resistivity in cell adhesion.
abstract: 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 rhoJ=rJdJ by combining measurements of the sheet resistance rJ and of the distance dJ 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 Omega cm to 750 Omega cm and find that the sheet resistance rJ is proportionally enhanced, but that the distance is invariant around dJ=75 nm. In all cases, the resulting resistivity rhoJ 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.
authors.affiliation: Department of Membrane and Neurophysics, Max Planck Institute for Biochemistry, Martinsried/Munich, Germany.
authors.forename: Raimund
authors.initials: R
authors.lastname: Gleixner
authors.forename: Peter
authors.initials: P
authors.lastname: Fromherz
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D002450:Cell Communication; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D004553:Electric Conductivity; D017097:Electric Impedance; D004563:Electrochemistry / Q000379:methods*; D004573:Electrolytes / Q000737:chemistry; D004594:Electrophysiology / Q000379:methods*; D005109:Extracellular Matrix / Q000378:metabolism; D005110:Extracellular Space; D005353:Fibronectins / Q000737:chemistry; D005583:Fourier Analysis; D006801:Humans; D007365:Intercellular Junctions; D008564:Membrane Potentials; D008856:Microscopy, Fluorescence; D009474:Neurons / Q000378:metabolism; D011107:Polylysine / Q000737:chemistry; D051381:Rats; D012825:Silicon / Q000737:chemistry; D013997:Time Factors
chemical_list: D004573:Electrolytes; D005353:Fibronectins; D011107:Polylysine; D012825:Silicon