title: Ouabain increases gap junctional communication in epithelial cells.
abstract: OBJECTIVE
  The finding that endogenous ouabain acts as a hormone prompted efforts to elucidate its physiological function. In previous studies, we have shown that 10 nM ouabain (i.e., a concentration within the physiological range) modulates cell-cell contacts such as tight junctions and apical/basolateral polarity. In this study, we examined whether 10 nM ouabain affects another important cell-cell feature: gap junction communication (GJC).
  
  
  METHODS
  We employed two different approaches: 1) analysis of the cell-to-cell diffusion of neurobiotin injected into a particular MDCK cell (epithelial cells from dog kidneys) in a confluent monolayer by counting the number of neighboring cells reached by the probe and 2) measurement of the electrical capacitance.
  
  
  RESULTS
  We found that 10 nM ouabain increase GJC by 475% within 1 hour. The Na+-K+-ATPase acts as a receptor of ouabain. In previous works we have shown that ouabain activates c-Src and ERK1/2 in 1 hour; in the present study we show that the inhibition of these proteins block the effect of ouabain on GJC. This increase in GJC does not require synthesis of new protein components, because the inhibitors cycloheximide and actinomycin D did not affect this phenomenon. Using silencing assays we also demonstrate that this ouabain-induced enhancement of GJC involves connexins 32 and 43.
  
  
  CONCLUSIONS
  Ouabain 10 nM increases GJC in MDCK cells.
authors.affiliation: Department of Physiology, Biophysics and Neurosciences, Center For Research and Advanced Studies (Cinvestav), México D. F., México.
authors.forename: Arturo
authors.initials: A
authors.lastname: Ponce
authors.forename: Isabel
authors.initials: I
authors.lastname: Larre
authors.forename: Aida
authors.initials: A
authors.lastname: Castillo
authors.forename: Refugio
authors.initials: R
authors.lastname: García-Villegas
authors.forename: Adrián
authors.initials: A
authors.lastname: Romero
authors.forename: Catalina
authors.initials: C
authors.lastname: Flores-Maldonado
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Martinez-Rendón
authors.forename: Rubén Gerardo
authors.initials: RG
authors.lastname: Contreras
authors.forename: Marcelino
authors.initials: M
authors.lastname: Cereijido
mesh_terms: D000818:Animals; D002450:Cell Communication / Q000187:drug effects*; D004285:Dogs; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D017629:Gap Junctions / Q000187:drug effects*; D061985:Madin Darby Canine Kidney Cells; D010042:Ouabain / Q000008:administration & dosage*
chemical_list: D010042:Ouabain