Activation of Ca2+ -activated potassium channels is involved in lysophosphatidylcholine-induced monocyte adhesion to endothelial cells

Ali Erdogan, Justus-Liebig-University of Giessen,Germany
Martina Barbara Schaefer, University of Giessen Lung Center (UGLC), Germany
Christoph Ruediger Wolfram Kuhlmann, Justus-Liebig-University of Giessen, Germany
Astrid Most, Justus-Liebig-University of Giessen, Germany
Marc Hartmann, Justus-Liebig-University of Giessen,Germany
Konstantin Mayer, University of Giessen Lung Center (UGLC),Germany
Fabrice Christoph Renner, University of Giessen Lung Center (UGLC), Germany
Claudia Schaefer, Justus-Liebig-University of Giessen, Germany
Yaser Abdallah, Aga Khan University
Hans Hoelschermann, Justus-Liebig-University of Giessen, Germany
Christian Alexander Schaefer, Justus-Liebig-University of Giessen,Germany

This work was published before the author joined Aga Khan University.



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).

Methods and 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.


Activation of the endothelial BK(Ca) plays an important role in monocyte adhesion to endothelial cells.