Thromboxane A2 analogue (U-46619) stimulates vascular PGI2 synthesis.

Since platelet release reaction products (e.g. serotonin, ADP) stimulate prostacyclin (PGI2) release in vitro, we have investigated whether thromboxane A2 (TXA2) also has a similar effect. An analogue, U-46619, was used for the experiments, since TXA2 is extremely unstable. U-46619 stimulated rat aortic PGI2 release; this stimulation was abolished by (a) EDTA and (b) verapamil. We conclude that TXA2 is a calcium-dependent stimulator of PGI2 release; this property may be relevant to the limitation of platelet aggregates in vivo and to vascular injury.