Increased sensitivity of arachidonic acid-induced platelet aggregation in the presence of carbon dioxide

Abstract

1 The effects of carbon dioxide on citrated human platelet-rich plasma (PRP) have been studied as a means of imitating the changes in pH and Pco₂ observed in inflammation and tissue fluid stasis. 2 Adenosine diphosphate (ADP)-induced platelet aggregation was inhibited in CO₂-treated PRP. 3 In contrast, CO₂-treated platelets were rendered up to eight times more sensitive to sodium arachidonate and this effect could be imitated by the addition of exogenous calcium 1 min before the addition of arachidonate. 4 The effects of CO₂ on ADP-induced and arachidonate-induced aggregation were abolished if the CO₂ was allowed to disperse from treated PRP subsequently exposed to air, suggesting no permanent alteration in platelet metabolism. 5 The increased sensitivity of arachidonate-induced aggregation with lowered pH may be a significant factor in influencing platelet behaviour in haemostasis.