The Journal of laboratory and clinical medicine
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Suspensions of platelet-rich plasma (PRP) or gel-separated platelets (GSP) can be used to evaluate clot retraction subsequent to platelet aggregation and fibrin formation. PRP (200,000 per cubic millimeter) or GSP (200,000 or 100,000 per cubic millimeter) are diluted 1:10 (PRP) or 1:8 (GSP) in phosphate buffer, pH 7.4, and clotted with a high concentration (2.5 U. per milliliter) of thrombin. Human fibrinogen (25 mg. per cent) is added to GSP prior to dilution. ⋯ High concentrations of PGE1 (to 6 x 10(-6) M) do not inhibit aggregation of GSP, fibrin formation, or platelet-fibrin interaction induced by 2.5 U. per milliliter of thrombin. In contrast, PGE1 concentrations as low as 1.5 to 3.0 x 10(-8) M inhibit clot retraction in both the dilute PRP and GSP systems. Thus, using dilute PRP or GSP the effects of platelet aggregation inhibitors on clot retraction can be determined independently of effects on platelet aggregation.