title: Activation of Ca2+ -activated potassium channels is involved in lysophosphatidylcholine-induced monocyte adhesion to endothelial cells.
abstract: OBJECTIVE
  Ca(2+)-activated K(+)-channels (BK(Ca)) play an important role in lysophosphatidylcholine (LPC)-induced endothelial dysfunction. Aim of our study was to investigate whether LPC-induced activation of BK(Ca) is also involved in monocyte adhesion to endothelial cells (EC).
  
  
  RESULTS
  Measurement of membrane potential (MP) was performed using the fluorescence dye DiBAC. Adhesion of the monocytotic cell line U937 to EC was analysed by (3)[H]-thymidine-adhesion-assay. Expression of ICAM-1 and VCAM-1 were analyzed by FACS. LPC induced a hyperpolarization of EC in a dose-dependent manner with the maximum seen with 2 microM. This was prevented by the BK(Ca)-inhibitor iberiotoxin (IBX, 100nM). Adhesion of U937 cells to EC was increased after stimulation of EC with LPC. This effect was time-dependent with the maximum seen after 4h. LPC-induced adhesion was significantly reduced when EC were co-incubated with IBX, or NAD(P)H oxidase inhibitor diphenyleneiodonium (DPI, 5 microM) and also blocked by addition of 2-aminoethoxydiphenylborate (2-APB, 100 microM) or the calcium-chelator BAPTA (10 microM). Stimulation of U937 cells with LPC did not result in an increased adhesion to unstimulated EC.
  
  
  CONCLUSIONS
  Activation of the endothelial BK(Ca) plays an important role in monocyte adhesion to endothelial cells.
authors.affiliation: Justus-Liebig-University of Giessen, Department of Cardiology and Angiology, Giessen, Germany.
authors.forename: Ali
authors.initials: A
authors.lastname: Erdogan
authors.forename: Martina Barbara
authors.initials: MB
authors.lastname: Schaefer
authors.forename: Christoph Ruediger Wolfram
authors.initials: CR
authors.lastname: Kuhlmann
authors.forename: Astrid
authors.initials: A
authors.lastname: Most
authors.forename: Marc
authors.initials: M
authors.lastname: Hartmann
authors.forename: Konstantin
authors.initials: K
authors.lastname: Mayer
authors.forename: Fabrice Christoph
authors.initials: FC
authors.lastname: Renner
authors.forename: Claudia
authors.initials: C
authors.lastname: Schaefer
authors.forename: Yaser
authors.initials: Y
authors.lastname: Abdallah
authors.forename: Hans
authors.initials: H
authors.lastname: Hoelschermann
authors.forename: Christian Alexander
authors.initials: CA
authors.lastname: Schaefer
mesh_terms: D050197:Atherosclerosis / Q000276:immunology* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects / Q000276:immunology*; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D004730:Endothelium, Vascular / Q000166:cytology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000037:antagonists & inhibitors / Q000502:physiology*; D008244:Lysophosphatidylcholines / Q000494:pharmacology; D009000:Monocytes / Q000166:cytology*; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009861:Onium Compounds / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism; D020298:U937 Cells; D014471:Umbilical Veins / Q000166:cytology; D014657:Vasculitis / Q000276:immunology* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D051036:Large-Conductance Calcium-Activated Potassium Channels; D008244:Lysophosphatidylcholines; D009861:Onium Compounds; D010455:Peptides; D017382:Reactive Oxygen Species; C007517:diphenyleneiodonium; C064719:iberiotoxin; D019255:NADPH Oxidases; D002118:Calcium