An important physiological anti-thrombotic function has been suggested for plasma
fibronectin and the reticuloendothelial system. The current study evaluated the effects
of specific immunological fibronectin depletion and fibronectin supplementation upon
resistance to infusion of thrombin and ADP in terms of mortality, mean arterial blood
pressure and circulating levels of platelets, fibrinogen and fibrin degradation products.
Mortality data indicated that rats with reduced fibronectin levels had reduced resistance
to thrombin or adenosine diphosphate infusion. The increased lethality was characterized
by reduced circulating levels of fibrinogen and platelets while fibrin degradation
product levels rose. The infusion of ADP or thrombin in fibronectin supplemented rats
failed to elicit higher mortality or reduce fibrinogen or platelet levels further.
These data are consistent with the hypothesis that resistance to excessive coagulation
and/or platelet aggregation is correlated to circulating plasma fibronectin levels.
It is suggested that by direct effects and/ or acting as an opsonin for RES phagocytosis,
plasma fibronectin acts as an important anti-thrombotic mechanism.
Keywords
Plasma fibronectin - Thrombosis - Reticuloendothelial system Adenosine diphosphate
- Thrombin - Platelets - Fibrinogen
