RT Journal Article SR Electronic T1 GAP JUNCTIONS AND CONNEXIN HEMICHANNELS UNDERPIN HAEMOSTASIS AND THROMBOSIS JF Heart JO Heart FD BMJ Publishing Group Ltd and British Cardiovascular Society SP A18 OP A18 DO 10.1136/heartjnl-2014-306916.53 VO 100 IS Suppl 4 A1 S Vaiyapuri A1 CI Jones A1 P Sasikumar A1 LA Moraes A1 MS Ali A1 T Sage A1 AM Simon A1 M Mahaut-Smith A1 JM Gibbins YR 2014 UL http://heart.bmj.com/content/100/Suppl_4/A18.1.abstract AB Connexins are a widespread family of membrane proteins that assemble into hexameric hemichannels, also known as connexons. Connexons regulate membrane permeability in individual cells or couple between adjacent cells to form gap junctions and thereby provide a pathway for regulated intercellular communication. We have now examined the role of connexins in platelets, blood cells that circulate in isolation, but upon tissue injury adhere to each other and the vessel wall to prevent blood loss and facilitate wound repair. We report the presence of connexins in platelets, notably connexin37, and that the formation of gap junctions within platelet thrombi is required for the control of clot retraction. Inhibition of connexin function modulated a range of platelet functional responses prior to platelet-platelet contact, and reduced laser induced thrombosis in vivo in mice. Deletion of the Cx37 gene (Gja4) in transgenic mice reduced platelet aggregation, fibrinogen binding, granule secretion and clot retraction indicating an important role for Cx37 hemichannels and gap junctions in platelet thrombus function. Together, these data demonstrate that platelet gap junctions and hemichannels underpin the control of haemostasis and thrombosis and represent potential therapeutic targets.