Adenosine diphosphate induced platelet aggregation and release reaction in heparinized platelet rich plasma and the influence of added citrate.

Platelets in heparinized platelet-rich plasma (PRP) from 54 volunteers were examined for their ability to aggregate and to release tritiated 5-hydroxy tryptamine (3H-5HT) in response to adenosine diphosphate (ADP). Release of 3H-5HT was considerable in 26 of the preparations. When release was high, lower concentrations of ADP were required to induce irreversible aggregation. Second phase aggregation reflected extensive release reaction. Citrate always augmented the release induced by ADP.