Prostacyclin and thromboxane A2 synthesis are increased in acute lower limb ischaemia.

Prostacyclin (PGI2) and thromboxane A2 (TXA2) play an important role in the pathophysiology of various cardiovascular diseases. The balance between PGI2 and TXA2 regulates the interaction between platelets and the vessel wall in vivo. In this study we measured PGI2 and TXA2 synthesis by analysing their urinary index metabolites 2,3-dinor-6-keto-PGF1 alpha and 11-dehydro-TXB2, respectively, in acute (10 patients) and chronic (10 patients) lower limb ischaemia. Both PGI2 and TXA2 synthesis were increased about two-fold in patients with acute lower limb ischaemia compared to chronic lower limb ischaemia. However, the PGI2/TXA2 ratio was more or less the same in acute and chronic lower limb ischaemia. In patients with acute lower limb ischaemia caused by thrombotic occlusion, PGI2 and TXA2 formation were about two times higher than in patients with acute lower limb ischaemia caused by embolic occlusion. Elevation of PGI2 and TXA2 synthesis in acute lower limb ischaemia may reflect increased platelet-vascular wall interactions without changing the PGI2/TXA2 ratio.