Aspirin effect on platelet antiplasmins release.

Euglobulins of platelet poor plasma containing resuspended washed platelets produced a significant decrease of the lysis areas with regard to euglobulins of platelet poor plasma alone; this decrease correlated with the number of platelets. Euglobulins of platelet poor plasma containing washed platelets activated with collagen (2 and 20 micrograms/ml) showed lower lysis areas on fibrin plates compared with euglobulins containing non-activated platelets (p 0.001). The higher number of platelets, the lower the lysis area. Aspirin had no effect upon antiplasmin activity either in non-activated or in activated platelets. We must consider the possibility that platelet antiplasmins could be released by different metabolic pathways than via the cyclooxygenase pathway or that they are not stored in -granules.