Procoagulant activity of platelets in recalcified plasma

High-spun platelet-poor plasma (HSPPP) and platelet-rich plasma (PRP), prepared with minimal contact activation and pH shifts, were recalcified with little dilution in the presence of phospholipid prepared from chloroform-extracted, acetone-dried brain tissue. The clotting times of HSPPP and PRP were the same whether or not the platelets in PRP were first incubated or aggregated with ADP or with collagen. This suggests that platelet procoagulant activity in normal recalcified plasma derives only from provision of platelet phospholipid.