title: Transport of clonidine at cultured epithelial cells (JEG-3) of the human placenta.
abstract: OBJECTIVE
  This study was performed to characterize the uptake of the antihypertensive drug clonidine at epithelial cells of the human placenta (JEG-3) and its interaction with other cationic drugs.
  
  
  METHODS
  Uptake of [3H]clonidine into cells of the human choriocarcinoma cell line JEG-3 was investigated.
  
  
  RESULTS
  Uptake of [3H]clonidine into JEG-3 cells reached its maximum on the eighth day after seeding. Uptake of [3H]clonidine was linear for up to 1 min, Na+ independent, but strongly H+ dependent. The uptake rate of clonidine was saturable with an affinity constant (Kt) of 1.1 mM and a Vmax value of 27 nmol x min(-1) x mg(-1) of protein. Several cationic drugs such as clonidine, quinine, quinidine, and diphenhydramine strongly inhibited the [3H]clonidine uptake with Ki values around 1 mM.
  
  
  CONCLUSIONS
  Clonidine is transported across the placental epithelium by a carrier mediated process.
authors.affiliation: Membrane Transport Group, Biozentrum of the Martin-Luther-University Halle-Wittenberg, D-06120 Halle, Germany.
authors.forename: Johanna
authors.initials: J
authors.lastname: Müller
authors.forename: Reinhard
authors.initials: R
authors.lastname: Neubert
authors.forename: Matthias
authors.initials: M
authors.lastname: Brandsch
mesh_terms: D001692:Biological Transport / Q000502:physiology; D002460:Cell Line; D003000:Clonidine / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D010920:Placenta / Q000166:cytology* / Q000378:metabolism*
chemical_list: D003000:Clonidine