Abstract
In order to analyze the role of thromboxane A2 (TX-A2) during human platelet aggregation, changes in stable thromboxane B2 (Tx-B2) was studied with radioimmunoassay by Tx-A2 125I-tyramide. Platelet aggregation was induced by ADP, adrenalin, collagen, arachidonate and Tx-A2 mixture. Amounts of Tx-B2, ATP, ADP, cAMP and cGMP in platelet rich plasma and platelet poor plasma were measured before and during aggregation.
ATP and ADP were released out of platelets in aggregation by any agents. However, the concentration of Tx-B2 with ADP- and adrenalin-induced aggregation was remarkably lower than with collagen-, arachidonate- and Tx-A2 mixture- induced aggregation. cAMP level was decreased during aggregation, but did not relate to Tx-B2 level.
These results suggest that Tx-A2 involves in platelet aggregation in different ways according to stimulating agents.
