Regensburg 2007 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 5: Cell Adhesion

BP 5.4: Vortrag

Montag, 26. März 2007, 11:30–11:45, H44

Investigation of erythrocytes cell-cell adhesion using holographic optical tweezers — •Achim Jung¹, Ingolf Bernhardt², Lyubomira Ivanova², Lars Kaestner³, Peter Lipp³, and Christian Wagner¹ — ¹Department of Physics, Saarland University, 66041 Saarbrücken, Germany — ²Laboratory of Biophysics, Saarland University, 66041 Saarbrücken, Germany — ³Institute for Molecular Cell Biology, Saarland University, 66424 Homburg, Germany

Prostaglandin E₂ (PGE₂) and lysophosphatidic acid (LPA) are released from activated platelets. Using fluorescence imaging, spectral imaging and the patch-clamp technique, we recently provided evidence that these lipid-mediators at physiological concentrations activate a non-selective cation-channel in human red blood cells (RBCs). This results in a Ca²⁺ influx and the consecutive intracellular Ca²⁺ concentration increase. Ca²⁺ increases elicits the Ca²⁺-activated K⁺ channel (Gardos channel) in the RBC membrane resulting in K⁺ efflux and shrinkage of the cells. Therefore we have postulated that the PGE₂ and LPA responses of RBCs reveal a direct and active participation of these cells in blood clot formation. In order to test this hypothesis we set out to measure whether the intracellular Ca²⁺ increase leads to an adhesion force between individual RBCs. These measurements are making use of holographic optical tweezers based on a conventional fluorescence microscope. Experimentally the increase of the intracellular Ca²⁺ concentration was induced by the Ca²⁺ ionophore A23187.