title: Estimation of the effective intercellular diffusion coefficient in cell monolayers coupled by gap junctions.
abstract: OBJECTIVE
  A recently developed dye-based assay to study gap junction permeability is analysed. The assay is based on electroporation of dye into a large number of connexin 43 expressing cells, grown to confluency on electrically conductive slides. The subsequent intercellular spread of dye to non-electroporated parts of the monolayer enables estimation of the intercellular coupling. So far, the extent of dye spread has been analyzed in qualitative terms only and not in a manner based directly on the physics of the underlying diffusion process.
  
  
  METHODS
  We apply a continuum approximation assuming that the observed dye spread can be described by Fick's law of diffusion. Deduced from Fick's law, new measures are presented which directly relate the observed spread of dye to the diffusion coefficient.
  
  
  RESULTS
  The theoretical framework enables the estimation of an effective diffusion coefficient from Fick's law independently of the specific indicator substance used in the assay. For Lucifer Yellow, diffusion stops within few minutes after the electroporation. Therefore only an order-of-magnitude estimate of the diffusion coefficient can be given for this dye.
  
  
  CONCLUSIONS
  In terms of the underlying diffusion coefficient, the hitherto used measures give a relatively poor degree of quantification. In contrast, the present methods may yield direct information on the effective intercellular diffusion coefficient and hence provide additional and more precise information as to the permeability modulating effect of various substances.
authors: The Danish National Research Foundation, Centre for Cardiac Arrhythmias, Copenhagen, Denmark.
authors: Niels Erik
authors: NE
authors: Olesen
authors: Johannes P
authors: JP
authors: Hofgaard
authors: Niels-Henrik
authors: NH
authors: Holstein-Rathlou
authors: Morten Schak
authors: MS
authors: Nielsen
authors: Jens Christian Brings
authors: JC
authors: Jacobsen
mesh_terms: D000818:Animals; D002450:Cell Communication; D045744:Cell Line, Tumor; D003198:Computer Simulation; D018031:Connexin 43 / Q000235:genetics / Q000378:metabolism; D004058:Diffusion; D004553:Electric Conductivity; D018274:Electroporation; D005456:Fluorescent Dyes / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism*; D007546:Isoquinolines / Q000378:metabolism; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D010539:Permeability; D051381:Rats; D049490:Systems Biology; D014162:Transfection
chemical_list: D018031:Connexin 43; D005456:Fluorescent Dyes; D007546:Isoquinolines; C017475:lucifer yellow