Abstract
Hemostasis is a physiologic mechanism that maintains blood in a fluid state within the circulation. The blood-coagulation cascade has the ability to transduce a small initiating stimulus into a large fibrin clot, which is mediated by cellular components and soluble plasma proteins. The potentially explosive nature of this cascade is counterbalanced by natural anticoagulant mechanisms. The maintenance of adequate blood flow and the regulation of cell-surface activity control the local accumulation of activated blood-clotting enzymes and complexes. Antithrombin is a plasma protein that inhibits the blood serine proteases of the intrinsic and common coagulation pathways. Heparin-like molecules, heparan sulfate proteoglycans, are closely associated with endothelial cells and enhance the action of circulating antithrombin. In this session, the endothelial heparan sulfate and antithrombin system, which plays an important role in the natural hemostatic balance to maintain the blood fluidity, will be discussed through the data from the congenital deficient mouse-models, i.e. KO mice. [J Physiol Sci. 2006;56 Suppl:S48]
