Protection of Single-chain Urokinase-type Plasminogen Activator (scu-PA) in Aprotinin Treated Cardiac Surgical Patients Undergoing Cardiopulmonary Bypass

Summary

Intraoperative high-dose aprotinin administration has been shown to reduce the intra-and postoperative blood loss in cardiac surgery. The haemostatic effect has been attributed to platelet preserving properties and to inhibition of contact activation reducing thrombotic and fibrinolytic activity during and after cardiopulmonary bypass (CPB).

Here we report on the effects of aprotinin on urokinase-type plasminogen activator, especially on the protection of the zymogen singlechain urokinase-type plasminogen activator (scu-PA). scu-PA occurs cell associated as well as free in the circulation (concentration 50 pM, half-life 5 min), and is potentially activated by kallikrein and plasmin, both potent targets for aprotinin. The generated active two-chain u-PA (tcu-PA) is a powerful activator of fibrinolysis.

Sixteen male patients undergoing myocardial revascularization were randomly assigned to aprotinin treatment (A) or control group (C).

Plasma concentration of total u-PA antigen and of the specific forms scu-PA(zymogen) and tcu-PA(active enzyme) were measured at different stages intraoperatively and two hours postoperatively. After an initial drop due to haemodilution at the onset of CPB, the concentrations of circulating u-PA forms restored intraoperatively in A, but remained subnormal in C until the end of the observation period. The concentration of total u-PA antigen of shed mediastinal blood was both in A and C two-fold higher than in the circulation, but the antigen was preserved as the zymogen scu-PA in A and largely converted to an inactive, non activatable form in C. Intra- and postoperative blood losses were less than half the amount in A as compared to C.

It is concluded that without aprotinin administration activation of circulatory scu-PA occurs, accompanied by stimulation of fibrinolysis and bleeding, finally resulting in elimination of tcu-PA complexed with endogenous inhibitors. Furthermore, cellular release of scu-PA occurs at or near the bleeding sites, as evidenced by the two-fold higher u-PA antigen concentration in the shed mediastinal blood. The released scu-PA is also activated and subsequently converted to an inactive form unless aprotinin is administered. High-dose aprotinin application during CPB effectively protects circulating and released scu-PA from activation and attenuates bleeding consequences.

• References

• 1 Royston D, Bidstrup B, Taylor K, Sapsford R. Effect of aprotinin on the need for blood transfusion after repeat open heart surgery. 1987; Lancet 2: 1289-1291
• 2 Dietrich W, Barankay A, Dilthey G, Henze R, Niekau E, Sebening F, Richter JA. Reduction of homologous blood requirement in cardiac surgery by intraoperative aprotinin application-clinical experience in 152 cardiac surgical patients. J Thorac Cardiovasc Surg 1989; 37: 92-98
• 3 Gebhard W, Tschesche H, Fritz H. Biochemistry of aprotinin and aprotinin-like enzymes. In: Protease Inhibitors. Barrett A, Salvesen G. eds Elsevier; Amsterdam: 1986. pp 375-388
• 4 Emerson T. Pharmacology of aprotinin and efficacy during cardiopulmonary bypass. Cardiovasc Drug Rev 1989; 7: 127-140
• 5 Lu H, Soria C, Commin P, Piwnica SJ A, Schumann F, Regnier O, Legrand Y. CJP. Hemostasis in patients undergoing extracorporeal circulation: The effect of aprotinin (Trasylol). Thromb Haemost 1991; 66: 633-637
• 6 Kluft C. Pathomechanisms of defective hemostasis during and after extracorporeal circulation: contact phase activation. In: Blood use in cardiac surgery Friedel N, Heitzer R, Royston D. eds 1991. pp 10-15
• 7 Dietrich W, Spannagl M, Jochum M, Wendt P, Schramm W, Barankay A, Sebening F, Richter J. Influence of high dose aprotinin treatment on blood loss and coagulation patterns in patients undergoing myocardial revascularization. Anaesthesiology 1990; 73: 1119-1126
• 8 Lavee J, Savion N, Smelinsky A, Goor D, Mohr R. Platelet protection by aprotinin in cardiopulmonary bypass: electron microscopic study. Ann Thorac Surg 1992; 53: 477-481
• 9 Wildevuur CH R H, Eijsman L, Roozendaal KJ, Harder MP, Chang M, van OeverenW. Platelet preservation during cardiopulmonary bypass with aprotinin. Eur J Cardiothorac Surg 1989; 3: 533-538
• 10 Dietrich W, Richter J, Schramm W, Spannagl M. What is the mechanism of action of aprotinin - reply. Anesthesiology 1991; 75: 378-379
• 11 Spannagl M, Dietrich W, Beck A, Schramm W. High dose aprotinin reduces prothrombin and fibrinogen conversion in patients undergoing extracorporeal circulation for myocardial revascularization. Thromb Haemost 1994; 72: 159-160
• 12 Wachtfogel YT, Harpel PC, Edmunds LH, Colman RW. Formation of C1s-C1-inhibitor, kallikrein-C1-inhibitor, and plasmin-antiplasmin complexes during cardiopulmonary bypass. Blood 1989; 73: 468-471
• 13 Ichinose A, Fujikawa K, Suyama T. The activation of pro-urokinase by plasma kallikrein and its inactivation by thrombin. J Biol Chem 1986; 261: 3486-3489
• 14 Hauert J, Nicoloso G, Schleuning W-D, Bachmann F, Schapira M. Plasminogen activators in dextransulphateactivated euglobulin fractions: a molecular analysis of factor XII- and prekallikrein-dependent fibrinolysis. Blood 1989; 73: 994-999
• 15 Binnema D, Dooijewaard G, Turion P. An analysis of the activators of single-chain urokinase-type plasminogen activator (scu-PA) in the dextran sulphate euglobulin fraction of normal plasma and of plasma deficient in factor XII and prekallikrein. Thromb Haemost 1991; 65: 144-148
• 16 Kluft C, Dooijewaard G, Emeis J. Role of the contact system in fibrinolysis. Sem Thromb Haemost 1987; 13: 50-68
• 17 Dietrich W, Barankay A, Wendt P, Stemberger P, Spannagl M, Jochum M, Bliimel G, Richter J. Fibrinolysis caused by cardiopulmonary bypass and shed mediastinal blood transfusion - is it of clinical relevance. Adv Exp Med Biol 1988; 240: 405-410
• 18 Binnema D, van IerselJ, Doojewaard G. Quantitation of urokinase antigen in plasma and culture media by use of an ELISA. Thromb Res 1986; 43: 569-577
• 19 van HinsberghV, van denBerg, Fiers W, Dooijewaard G. Tumor necrosis factor induced the production of urokinase-type plasminogen activator by human endothelial cells. Blood 1990; 75: 1991-1998
• 20 Phillipe J, Dooijewaard G, Offner F, Turion P, Baele G, Leroux-Roels G. Granulocyte elastase, tumor necrosis factor-alpha and urokinase levels as prognostic markers in severe infection. Thromb Haemost 1992; 68: 19-23
• 21 Himmelreich G, Dooijewaard G, Breinl P, Bechstein WO, Neuhaus P, Kluft C, Riess H. Evolution of urokinase-type plasminogen activator (u-PA) and tissue-type plasminogen activator in orthotopic liver transplantation. Thromb Haemost 1993; 69: 56-59
• 22 Nauland U, Dooijewaard G, Rijken D C. Evidence for the occurrence of thrombin-inactivated single-chain urokinase-type plasminogen activator in plasma and other body fluids. Thromb Haemost 1993; 69 (06) A 1000
• 23 Gram J, Janetzko T, Jespersen J, Bruhn H. Enhanced effective fibrinolysis following the neutralization of heparin in open heart surgery increases the risk of post-surgical bleeding. Thromb Haemost 1990; 63: 241-245
• 24 Teufelsbauer H, Proidl S, Havel M, Vukovic Th. Early activation of Hemostasis during Cardiopulmonary Bypass: Evidence for Thrombin Mediated Hyperfibrinolysis. Thromb Haemost 1992; 68: 250-252
• 25 Pannell R, Black J, Gurewich V. Complementary modes of action of tissue-type plasminogen activator and prourokinase by which their synergistic effect on clot lysis may be explained. J Clin Invest 1988; 81: 853-859
• 26 Plesner T, Ploug M, Ellis V, Ronne E, Hoyer-Hansen G, Wittrup M, Pedersen TL, Tscherning T, Dano K, Hansen NE. The receptor for urokinase-type plasminogen activator and urokinase is translocated from two distinct intracellular comparments to the plasma membrane on stimulation of human neutrophils. Blood 1994; 83: 8008-8015
• 27 Gurewich V, Johnstone M, Loza JP, Panell R. Pro-urokinase and prekallikrein are both associated with platelets. Implications for the intrinsic pathway of fibrinolysis and for therapeutic thrombolysis FEBS LETTERS 1993; 318: 317-321