title: Effect of ticagrelor on endothelial calcium signalling and barrier function.
abstract: The P2Y12receptor is a Gi-coupled receptor whose activation inhibits adenylyl cyclase and thereby reduces the concentration of intracellular cAMP. Here the hypothesis was tested whether AR-C 66096 or ticagrelor, two direct-acting and reversibly binding P2Y12receptor antagonists, protect endothelial cell (EC) barrier function by raising intracellular cAMP in ECs. The study was carried out on primary human umbilical vein ECs (HUVECs) and human pulmonary microvascular ECs (hPMECs). AR-C66096 (10 µM) induced a 50 % increase in cAMP in ECs whereas ticagrelor (2-10 µM) had no effect. Likewise, AR-C666096 antagonised thrombin-induced hyperpermeability in both HUVECs and hPMECs, but ticagrelor had no effect on basal EC monolayer permeability. Ticagrelor, however, sensitised ECs for thrombin-induced hyperpermeability and potentiated the thrombin effect. Ticagrelor but not AR-C66096 caused an increase in cytosolic calcium ([Ca2+]i). This increase in [Ca2+]iwas abrogated by LaCl3(Ca2+influx inhibitor) but not by xestospongin C (IP3receptor antagonist) or by depletion of intracellular stores with thapsigargin, suggesting a Ca2+influx from the extracellular space. Accordingly, ticagrelor caused an increase in myosin light chain (MLC) phosphorylation, an important regulator of EC contractile machinery and thus permeability, which was abrogated by LaCl3. The ability of ticagrelor to potentiate EC permeability was abrogated by a MLC kinase inhibitor (ML-7; 10 µM). Our data demonstrate that the P2Y12receptor antagonist AR-C66096 exerts a protective effect on ECs in vitro, possibly by raising intracellular cAMP, whereas ticagrelor sensitises EC barrier function by inducing Ca2+influx and activating downstream EC contractile machinery.
authors.forename: Dursun
authors.initials: D
authors.lastname: Gündüz
authors.forename: Christian
authors.initials: C
authors.lastname: Tanislav
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Schlüter
authors.forename: Rainer
authors.initials: R
authors.lastname: Schulz
authors.forename: Christian
authors.initials: C
authors.lastname: Hamm
authors.affiliation: PD Dr. Muhammad Aslam, Department of Cardiology and Angiology, University Hospital Giessen, Justus Liebig University, Aulweg 129, 35392 Giessen, Germany, Tel.: +49 641 99 42248, Fax: +49 641 99 42259, E-mail: muhammad.aslam@med.uni-giessen.de.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Aslam
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects*; D002199:Capillary Permeability / Q000187:drug effects*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D061307:Human Umbilical Vein Endothelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D008168:Lung / Q000098:blood supply*; D055806:Microvessels / Q000187:drug effects* / Q000378:metabolism; D018994:Myosin Light Chains / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D010766:Phosphorylation; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D058921:Purinergic P2Y Receptor Antagonists / Q000494:pharmacology*; D058925:Receptors, Purinergic P2Y12 / Q000187:drug effects / Q000378:metabolism; D000077486:Ticagrelor; D013997:Time Factors
chemical_list: C092108:2-propylthio-D-beta,gamma-difluoromethylene ATP; D018994:Myosin Light Chains; C548576:P2RY12 protein, human; D010975:Platelet Aggregation Inhibitors; D058921:Purinergic P2Y Receptor Antagonists; D058925:Receptors, Purinergic P2Y12; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D009219:Myosin-Light-Chain Kinase; D000077486:Ticagrelor; D000241:Adenosine
keywords: AR-C66096; P2Y12 receptors; contractile machinery; dipyridamole; permeability