Thromb Haemost 1985; 54(03): 639-644
DOI: 10.1055/s-0038-1660088
Original Article
Schattauer GmbH Stuttgart

Plasma Fibronectin Enhances Fibrinolytic System In Vitro

Nisan Gilboa
The Wadsworth Center for Laboratories and Research, New York State Department of Health, and the Departments of Pediatrics and Physiology, Albany Medical College, Albany, New York, USA
,
John E Kaplan
The Wadsworth Center for Laboratories and Research, New York State Department of Health, and the Departments of Pediatrics and Physiology, Albany Medical College, Albany, New York, USA
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Publikationsverlauf

Received 12. Februar 1985

Accepted 30. Juli 1985

Publikationsdatum:
19. Juli 2018 (online)

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Summary

The effects of plasma fibronectin on the fibrinolytic system were studied in vitro. Fibronectin caused a time and concentration-dependent increase (up to 99% with 330 ug/ml) in the amidolytic activity of tissue plasminogen activator (TPA) but not of urokinase. In the presence of fibronectin the Km of the amidolytic activity of TPA decreased without a change in Vmax. It also caused a concentration-dependent increase in lys-plas-minogen activation by TPA (up to 825% with 375 ug/ml) and by urokinase (up to 400% with 250 ug/ml), as well as in the amidolytic activity of plasmin (up to 55% with 300 ug/ml). Fibronectin did not enhance the activation of glu-plasminogen. In the presence of fibronectin the Km of lys-plasminogen activation decreased without a change in Vmax. In purified systems fibronectin significantly shortened the clot lysis time (CLT) by up to 28% and 30% in TPA- and plasmin-activated lysis, respectively. The presence of Ca2+ did not change fibronectin’s effect on CLT. Clots of non-fibronectin-depleted plasma were lysed up to about twice as fast as the clots of fibronectin-depleted plasma. In conclusion, physiologic concentrations of fibronectin enhanced the fibrinolytic system in vitro. Further studies will be required to elucidate the mechanisms involved and to document whether fibronectin has a similar effect in vivo.