Active metabolism of phosphatidylethanolamine plasmalogen in stimulated platelets, analyzed by high performance liquid chromatography

To investigate the stimulus-linked metabolism of platelet phosphatidylethanolamine plasmalogen (PEP) which is not separable from diacyl PE by conventional methods, phospholipids extracted from stimulated platelets prelabelled with 3H-arachidonate (AA) were analyzed by high performance liquid chromatography (HPLC) reported by us (Thrombos. Res. 36, 335, 1984 & 42, 461, 1986). When washed human platelets were stimulated by thrombin or A23187, the amount of PEP monitored by optical density was significantly decreased in consort with phosphatidylcholine (PC), indicating an active participation of PEP in the liberation of AA. Unlike other major phospholipids, PEP hardly incorporated 3H-AA in the resting state but upon stimulation gradual but significant uptake of 3H-AA by PEP was observed. The amount of uptake was not affected by the level of cytosolic free Ca2+ or by the amount of liberated AA, ruling out a direct participation of this unique reacylation process as negative feed back system.