Differences in the stability of prostacyclin in human, rabbit and rat plasma.

Prostacyclin (PGI2) is a potent vasodilator and inhibitor of platelet aggregation, however, its half-life in aqueous solutions at neutral or acid pH is very short. In this study we have investigated the stability of PGI2 in plasma from different species and have demonstrated that the half-life of the anti-aggregatory and the hypotensive activity of PGI2 is considerably prolonged in human plasma. Interestingly the activity of PGI2 was not maintained on incubation in rat or rabbit plasma indicating that the stabilising factor may be confined to human plasma. Whether such stabilisation prolongs the half-life of PGI2 in the human circulation merits investigation.