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

Prostacyclin (PGl₂) and thromboxane A₂ (TXA₂) play an important role in the pathophysiology of various cardiovascular diseases. The balance between PGl₂ and TXA₂ regulates the interaction between platelets and the vessel wall in vivo. In this study we measured PGl₂ and TXA₂ synthesis by analysing their urinary index metabolites 2,3-dinor-6-keto-PGF_1α and 11-dehydro-TXB₂, respectively, in acute (10 patients) and chronic (10 patients) lower limb ischaemia. Both PGl₂ and TXA₂ synthesis were increased about two-fold in patients with acute lower limb ischaemia compared to chronic lower limb ischaemia. However, the PGl₂/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, PGl₂ and TXA₂ formation were about two times higher than in patients with acute lower limb ischaemia caused by embolic occlusion. Elevation of PGl₂ and TXA₂ synthesis in acute lower limb ischaemia may reflect increased platelet-vascular wall interactions without changing the PGl₂/TXA₂ ratio.