Antithrombotic activity of kininogen is mediated by inhibitory effects of domain 3 during arterial injury in vivo.

Antithrombotic activity of kininogen is mediated by inhibitory effects of domain 3 during, arterial injury in vivo. Am J Physiol Heart Circ Physiol 292: H2959-H2965, 2007. First published February 9 2007; doi: 10.1152/ajpheart.00730.2006. - High-molecular-weight kininogen (HK) and its domain 3 (D3) exhibit anticoagulant properties and inhibit platelet activation it low thrombin concentration in vitro. We hypothesized that the rapid occlusive thrombosis in HK-deficient (HKd) rats following endothelial injury of the aorta results front enhanced platelet aggregation by thrombin. The effects of D3 (G235-M357) or D3-derived peptides oil thrombosis in vivo were tested. D3 and its exon 7C terminal peptide (E7CP, K270-Q292), expressed as glutathione S-transferase (GST) fusion proteins (GST-D3. GST-E7CP). or GST alone. as well as cleaved HK (HKa) or synthetic peptide E7CP. were infused intravenously 10 min before endothelial injury. Blood flow was reduced down to 10% of baseline flow within 28 +/- 5.2 min by a platelet-fibrin thrombus in GST-treated HKd rats compared with >240 unit in GST-treated normal HK rats (wild type). GST-D3, GST-E7CP, HKa, or E7CP infusion prolonged the flow time to 233, >240, 223, and >240 min, respectively, in HKd rats. When GST-E7CP was infused 10 min after the injury, blood flow was maintained for >240 min. Thrombin-antithrombin concentrations were elevated by injury in HKd rats receiving GST front 35 to 55 mu g/l and decreased With GST-E7CP. HKa, or E7CP reconstitution to 40, 15, and 9 mu g/l, respectively. We conclude that HKd rats are prothrombotic and that HKa. kinino2en D3.,aid its fragruent E7CP modulate arterial thrombosis after endothelial injury.