Prostacyclin and the Mechanism of Action of Antithrombotic Drugs

S. Moncada
1979 VIIth International Congress on Thrombosis and Haemostasis   unpublished
The balance between the proaggregating thromboxane A2 and the antiaggregating prostacyclin forms a homeostatic mechanism for the control of platelet aggregability in vivo. Prostacyclin is a circulating substance released from the lungs which acts by stimulating adenylate cyclase leading to an increase of cyclic AMP in the platelets. The mechanism of antithrombotic action of phosphodiesterase inhibitors like dipyridamole depends on their ability to potentiate the effect of endogenous PGI2.
more » ... cyclin and TXA2 are inhibited by aspirin but the enzyme which synthesises TXA2 is more sensitive to the inhibitory effect of aspirin, therefore it is possible to administer doses of aspirin which by inhibiting selectively TXA2 will have an antithrombotic effect. Human studies demonstrate that cutaneous bleeding time is controlled by the balance between TXA2 and PGI2 and can be manipulated by using different doses of aspirin.
doi:10.1055/s-0039-1684477 fatcat:gcwzp24n35c4ja6rvbptjh7hnu