Paf-acether formation and arachidonic acid freeing from platelet ether-linked glyceryl-phosphorylcholine.

Ether-linked glyceryl-phosphorylcholines (GPC) are potential precursors for paf-acether biosynthesis. We show that such phospholipids are present in rabbit platelets in sufficient amounts to insure lyso paf-acether and paf-acether formation. Indeed, upon stimulation, platelets formed lyso paf-acether and paf-acether in amounts representing 10% and 0.2% of the total amounts of ether-linked GPC. Following preincubation with [3H]paf-acether, ether-linked GPC labelled at position 1 of the glycerol were detected in platelets. They were hydrolysed, and gave birth to lyso paf-acether upon platelet activation. Platelet ether-linked GPC labelled at position 2 with [3H]arachidonic acid (AA) were also hydrolyzed under the same experimental conditions. These data indicate that in rabbit platelets these phospholipids are precursors for paf-acether and AA, two mediators of platelet activation.