Paracellular barrier and junctional protein distribution depend on basolateral extracellular Ca2+ in cultured epithelia

C B Collares-Buzato, Gordon T.A. McEwan, M A Jepson, N L Simmons, B H Hirst

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The polarised nature of the increase in paracellular permeability induced by Ca(2+)-chelation with EGTA was investigated in several cultured epithelial cell lines. In strain I MDCK cells (canine kidney cells), a marked decrease (> 90%) in transepithelial electrical resistance (RT) and increase in mannitol and inulin permeabilities were only observed after addition of EGTA (for 4 h) to either basolateral (basal) or both (apical+basal) bathing solutions; apical Ca(2+)-chelation resulted in significant smaller changes (approximately 30%) in these variables. The increase in paracellular permeability upon basal EGTA addition was significantly lower than that produced by simultaneous apical and basal addition of 2 mM EGTA. A higher concentration of EGTA (20 mM) did not significantly eliminate this difference in potency between basal and apical+basal Ca(2+)-chelation. The polarised Ca(2+)-dependence of the paracellular barrier was associated with polarised effects on the junctional/cytoskeletal protein distribution. Basal or apical+basal EGTA addition induced substantial internalisation of uvomorulin with some cellular redistribution of the perijunctional actin ring and desmosomes and gaps in ZO-1 location between adjacent cells. In addition, polarised Ca(2+)-dependence of the paracellular barrier (assessed by measuring RT) was observed also in strain II MDCK and two human adenocarcinoma intestinal cell lines, Caco-2 and HCT-8, demonstrating generality of the phenomenon. Therefore, the data show a polarity in the ability of EGTA to enhance epithelial permeability and induce cellular redistribution of cytoskeletal/junctional proteins in several epithelia. The basolateral membrane sensitivity to Ca(2+)-chelation might be explained by the polarised distribution of uvomorulin.
Original languageEnglish
Pages (from-to)147-58
Number of pages12
JournalBiochimica et Biophysica Acta
Issue number2
Publication statusPublished - 30 Jun 1994


  • Animals
  • Cadherins
  • Calcium
  • Cell Line
  • Cell Membrane Permeability
  • Cytoskeletal Proteins
  • Dogs
  • Egtazic Acid
  • Electric Conductivity
  • Electric Impedance
  • Inulin
  • Mannitol
  • Potassium


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