title: Effects of caffeic acid phenethyl ester (CAPE) on membrane potential and intracellular calcium in human endothelial cells.
abstract: BACKGROUNG AND OBJECTIVES: Caffeic acid phenethyl ester (CAPE) is an active component of the resin propolis obtained from beehives. Propolis has a long history of medicinal use and a number of studies have already reported on some of its pharmaceutical properties. This study aimed to explore the effects of CAPE on the cytosolic Ca2+ concentration, cell proliferation, membrane potential and NO levels in human endothelial cells.
  
  
  METHODS
  Isolated human umbilical vein endothelial cells (HUVEC) were incubated with CAPE (1-100 µM) at 37°C for 48 hours. Cell proliferation was estimated by counting cell numbers with use of a Neubauer chamber. The effect of CAPE (1-100 µM) on the membrane potential was measured with the fluorescence dye DIBAC4(3) whereas its effect on the cytosolic Ca2+ concentration was measured by use of the fluorescence probe Fluo-3 AM (Invitrogen, Leiden, Netherlands). NO production was assayed using the flourophore DAF~AM (Invitrogen, Leiden, Netherlands). Changes in fluorescence intensity was determined with the GENios plate reader (Genios, Tecan, Austria).
  
  
  RESULTS
  A dose-dependent hyperpolarization of the endothelial cell membrane was observed with CAPE stimulation. The initial increase in the intracellular Ca2+ concentration showed a subsequent decrease over time. CAPE stimulation also resulted in an increase in NO production; however, at higher doses a decrease in NO levels was observed. HUVEC proliferation was inhibited by CAPE.
  
  
  CONCLUSIONS
  Here we report on the effect of CAPE stimulation on the cytosolic Ca2+ concentration, cell proliferation, membrane potential and NO production in HUVEC in a dose-dependent manner. These findings provide important insights into some potential key roles that both calcium and the membrane potential play in the CAPE activation of endothelial cells in a concentration-dependent manner.
authors.affiliation: Department of Internal Medicine, Wuppertal Research and Medical Center, Angiology Wuppertal, Germany. prof.erdogan@gempraxbalserstift.de
authors.forename: M
authors.initials: M
authors.lastname: Kamil Burgazli
authors.forename: N
authors.initials: N
authors.lastname: Aydogdu
authors.forename: A
authors.initials: A
authors.lastname: Rafiq
authors.forename: M
authors.initials: M
authors.lastname: Mericliler
authors.forename: R
authors.initials: R
authors.lastname: Chasan
authors.forename: A
authors.initials: A
authors.lastname: Erdogan
mesh_terms: D002109:Caffeic Acids / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects*; D009589:Nitrogen Oxides / Q000378:metabolism; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D002109:Caffeic Acids; D009589:Nitrogen Oxides; C055494:caffeic acid phenethyl ester; D010626:Phenylethyl Alcohol; D002118:Calcium