Release of biologically active substances from non-aggregating human platelets

Abstract

Human platelet rich plasma (PRP) prepared from healthy, male volunteers spontaneously release an anti-aggregatory, spasmogenic substance when incubated at 37°C. Similar biological activity was also observed following incubation of platelets resuspended in aqueous solution but not in incubated platelet poor plasma. Human PRP incubated at room temperature or on ice failed to release biologically active substances. Both anti-aggregatory and spasmogenic activity was detected following extraction of incubated PRP into ethyl acetate after acidification. Aspirin (0.9 g) pretreatment reduced the generation of both spasmogen and anti-aggregatory substance when blood was withdrawn 1 h but not 24 h after drug treatment. Indomethacin, flurbiprofen or aspirin (all 50 μM) incubated with human PRP in vitro did not affect the production of spasmogenic or anti-aggregatory activity. These results suggest that non-aggregating human platelets generate a spasmogenic, anti-aggregatory prostaglandin.