Metabolism of platelet-activating factor by blood platelets and plasma.

High performance liquid chromatography in combination with a radioactivity detector was used to study the metabolism of platelet-activating factor (1-0-alkyl-2-acetyl-sn-glycero-3-phosphocholine) by washed platelets, platelet-free plasma and platelet-rich plasma obtained from rabbits and humans. Degradation of platelet-activating factor to its 2-lyso derivative was observed in rabbit and human plasma. This degradation of platelet-activating factor in plasma was completely inhibited by diisopropylfluorophosphate and was partially inhibited by ethylenediamine tetraacetic acid. Washed platelets metabolized platelet-activating factor not only to the 2-lyso compound but also, by reacylation of this lyso intermediate, to an analogue of platelet-activating factor probably containing a long-chain acyl group at the sn-2 position. These transformations occurred, but to a lesser extent, in platelet-rich plasma.