Effects of anticoagulation on the interaction of human platelets with subendothelium in flowing blood.

The subendothelial surface of rabbit aorta was exposed to a laminar stream of native human blood using a perfusion chamber. The blood was drawn at a constant flow rate and 37 degrees C from a cubital vein through the annular space of the chamber by means of a roller pump. Platelet interaction with subendothelium and fibrin deposition were measured morphometrically. Native blood and blood anticoagulated with 15 mM citrate obtained from the same donor was investigated at arterial blood flow conditions. Platelet adhesion was significantly increased by the anticoagulation. In contrast, platelet spreading and adhesion-induced aggregation were significantly inhibited by citrate. The extent of fibrin deposition varied greatly from one donor to another and did not correlate with platelet adhesion. It is concluded that initially, the two hemostatic systems platelet adhesion-aggregation and coagulation function independently.