Efflux of granule constituents from platelets exposed to different mechanical forces.
The efflux of 14C-norepinephrine, 3H-serotonin and beta-thromboglobulin from platelets was compared with the extent of lysis in two different systems of incubation, in which Ca2+ and conventional platelet activating agents were omitted. In the first system platelets were incubated in buffer at 37 degrees C and gently shaken. Cell lysis was low and efflux of 14C-norepinephrine was 71-97% of total initial uptake after 24 hours. In the other system rotating plastic tubes at 20 degrees C were used which exposed the platelets to higher mechanical stress. Cell lysis and aggregation was already high after 10-30 minutes, but the efflux of 14C-norepinephrine and 3H-serotonin was lower and not parallel to cell lysis. The release of 14C-norepinephrine was higher than that of 3H-serotonin in both systems. There was a considerable release of beta-thromboglobulin from platelets remaining in plasma despite of a constant pH. These findings indicate that platelet lysis is independent of the release of platelet granule constituents.
D001792:Blood Platelets / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D002021:Buffers; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009638:Norepinephrine / Q000097:blood; D010974:Platelet Aggregation; D012701:Serotonin / Q000097:blood; D013314:Stress, Mechanical; D001620:beta-Thromboglobulin / Q000032:analysis
D002021:Buffers; D001620:beta-Thromboglobulin; D012701:Serotonin; D009638:Norepinephrine