The pH dependent platelet utilization of arachidonic acid and a thromboxane A2 mimetic, in vitro.

The effects of carbon dioxide (CO2) and pH on platelet aggregation in vitro have been studied to simulate pH changes observed in tissue fluid stasis and inflammation. Platelet aggregation induced by the 7-oxabicycloheptane mimetic of thromboxane A2 (TxA2) showed increased sensitivity in CO2-treated platelet-rich plasma (PRP). This effect is similar to that previously reported for arachidonate-induced aggregation. In contrast, aggregation of washed platelet suspensions (i.e. protein-free), in response to both arachidonate and TxA2 mimetic, was inhibited under acid conditions. These results confirm the importance of plasma proteins in the control of platelet function and support the hypothesis that the pH effects are dependent on these proteins.