Influence of mithramycin on some platelet functions in vitro

Platelet-rich plasma was incubated with mithramycin in vitro. This diminished platelet aggregation by ADP and adrenaline, but did not interfere with collagen-induced aggregation. Platelet factor 4 release was diminished by ADP and delayed when induced by adrenaline but normal when induced by collagen. Platelet factor 3 availability was not significantly impaired. Reptilase clot retraction was diminished when induced by ADP but normal when induced by collagen. Uptake of 14C-serotonin and 14C-adenine was slightly inhibited. There was no depression in platelet adhesion or release of serum aggregating activity.