title: The influence of the fibrinolytic system on the affinity of fibrinogen for the endothelial-plasma interface.
abstract: We use intravital fluorescence microscopy to study the endo-endothelial lining of microcirculatory vessels in vivo and in situ (exposed rat mesentery). In earlier experiments we found that fibrinogen had an affinity for the inner lining of microvessels, particularly venules. This affinity was specific to fibrinogen (and fibronectin); most other plasma proteins (albumin, antithrombin III, gamma-globulin) did not accumulate on the inner surface of microcirculatory blood vessels. We postulated the existence of receptors for fibrinogen and/or fibronectin on the endo-endothelial surface, whose turnover rate differed in arterioles and venules. Blockade of the intravascular coagulation process by heparin did not alter the interaction between fibrinogen and endothelium, but blockade of fibrinolytic activity by tranexamic acid increased the deposition of fibrinogen at the endothelial surface. In the present study we administrated a drug containing the bioflavonoids diosmin and hesperidin, which may activate tissue plasminogen activator. Such pretreatment significantly decreased the accumulation of fibrinogen at the endo-endothelial surface of the venules. We therefore conclude that the endothelial plasma interface is characterized by accumulation of fibrinogen which is not affected by thrombin-mediated activation of the coagulation system. In contrast, interactions between fibrinogen and endothelium are influenced by the fibrinolytic system, both of plasmatic and endothelial origin, thus representing an important aspect of the antithrombotic potential of the endothelium.
mesh_terms: D000818:Animals; D004145:Diosmin; D004730:Endothelium, Vascular / Q000378:metabolism / Q000502:physiology*; D005260:Female; D005340:Fibrinogen / Q000378:metabolism / Q000502:physiology*; D005342:Fibrinolysis; D006569:Hesperidin; D008833:Microcirculation / Q000378:metabolism / Q000502:physiology*; D011485:Protein Binding; D051381:Rats; D010959:Tissue Plasminogen Activator / Q000502:physiology
chemical_list: D004145:Diosmin; D005340:Fibrinogen; D006569:Hesperidin; D010959:Tissue Plasminogen Activator