García-Chávez J, Carrillo-Esper R, Majluf-Cruz A

Language: Spanish
References: 19
Page: 7-9
PDF size: 44.30 Kb.

ABSTRACT

The endothelium has several functions. While intact it maintains blood in a fluid state due to the action of several anticoagulant mechanisms. After wound occurred, hemostasis stops bleeding in two steps. The first is not permanent but helps controlling hemorrhage by vasoconstriction and platelet activation. Secondary hemostasis encompasses the fibrin formation process. Platelet cloth requires platelet adhesion, conversion of platelets into spheres, and secretion of agonists that allow platelet aggregation. Hemostasis requires a fibrin network in order to strength the platelet cloth. Fluid phase of hemostasis converts fibrinogen into fibrin by using thrombin at the end of these reactions. Thrombin generation depends on two pathways that differ in the way they activate FX although they follow a common pathway after activation of this last factor. Activated fibrinogen, also called fibrin monomer, polymerizes and forms fibrils. Moreover, thrombin auto-activates and activates several other hemostatic factors and platelets. Direct activation of secondary hemostasis through extrinsic pathway is brief and insufficient to hold hemostasis properly. Therefore, intrinsic pathway is a condition to achieve an adequate hemostatic function. Both, fibrinolysis and hemostasis deeply interact each other forming and degrading fibrin. Fibrinolysis prevents fibrin deposition in the vessel impeding obstruction of blood flow. It depends on plasmin which hidrolyses fibrinogen (fibrinogenlysis) and fibrin (fibrinolysis). Cloth formation occurs and persists only when and it is necessary. Starting, growing and maintenance of cloths are closely regulated in time and space. Human plasma has several agents that inhibit the activity of hemostatic and fibrinolytic factors and that may localize and regulate the hemostatic and fibrinolytic processes.

REFERENCES

1. Zucker MB. Platelet agglutination and vasoconstriction as factors in spontaneous hemostasis in normal, thrombocytopenic, heparinized, and hypothrombinemic rats. Am J Phyisol 1947;148:275-278.

2. Geng JG, Bevilacqua MP, Moore KL, McIntyre TM, Prescott SM, Kim JM, et al. Rapid neutrophil adhesion to activated endothelium mediated by GMP-140. Nature 1990;343:757-760.

3. Slack SM, Cui Y, Turitto VT. The effects of flow on blood coagulation and thrombosis. Thromb Haemost 1993;70:129-134.

4. Stenflo J, Fernlund P, Egan W, Roepstorff P. Vitamin K–dependent modifications of glutamic acid residues in prothrombin. Proc Natl Acad Sci USA 1974;71:2730-2733.

5. Furie B, Furie C. Molecular and cellular biology of blood coagulation. N Engl J Med 1992;326:800-806.

6. Blombäck B, Blombäck M. The molecular structure of fibrinogen. Ann NY Acad Sci 1972;202:77-97.

7. Mann KG, Jenny RJ, Krishnaswamy S. Cofactor proteins in the assembly and expression of blood clotting enzyme complexes. Annu Rev Biochem 1988;57:915-956.

8. Bevilacqua MP, Pober JS, Majeau GR. Interleukin 1 (IL-1) induces biosynthesis and cell surface expression of procoagulant activity in human vascular endothelial cells. J Exp Med 1984;160:618-623.

9. Yamamoto M, Nakagaki T, Kisiel W. Tissue factor-dependent autoactivation of human blood coagulation factor VII. J Biol Chem 1992;267:19089-19094.

10. Osterud B, Rapaport SI. Activation of factor IX by the reaction product of tissue factor and factor VII: Additional pathway for initiating blood coagulation. Proc Natl Acad Sci USA 1977;74:5260-5264.

11. Davie EW, Fujikawa K, Kisiel W. The coagulation cascade: Initiation, maintenance, and regulation. Biochemistry 1991;30:10363-10370.

12. Majluf-Cruz A, DeLa Cadena R. El sistema de contacto: su papel en la hemostasia y su relación con otros sistemas biológicos. En: Martínez-Murillo C, Quintana-González S. Manual de hemostasia y trombosis. Editorial Prado, 1996.

13. Bauer KA, Kass BL, ten Cate H, Hawiger JJ, Rosenberg RG. Factor IX is activated in vivo by the tissue factor mecahnism. Blood 1990;76:731-736.

14. Ruggeri ZM, Ware J. von Willebrand factor. FASEB J 1993;7:308-316.

15. Loskutoff DJ, Sawdey M, Keeton M, Schneiderman J. Regulation of PAI-1 gene expression in vivo. Thromb Haemost 1993;70:135-137.

16. Marder VJ, Shulman NR, Carroll, WR. High molecular weight derivatives of human fibrinogen produced by plasmin. I. Physicochemical and immunological characterization. J Biol Chem 1969;244:2111-2119.

17. Sappino AP, Huarte J, Vassalli J-D, Belin D. Sites of synthesis of urokinase and tissue-type plasminogen activators in the murine kindey. J Clin Invest 1991;87:762-770.

18. Rosenberg RD, Rosenberg SJ. Natural anticoagulant mechanisms. J Clin Invest 1984;74:1-6.

19. Esmon CT. The roles of protein C and thrombomodulin in the regulation of blood coagulation. J Biol Chem 1989;264:4743-4746.