The importance of the production of phosphatidic acid for the release of arachidonic acid in stimulated platelets.

Phosphatidic acid is formed by platelets as a result of the combined activities of phospholipase C and diacylglycerol kinase. The initial thrombin-activated phospholipase C-mediated reaction is quinacrine insensitive and is followed by quinacrine-sensitive phospholipase A2 activities. The phosphatidic acid released probably results in cellular calcium gating, which, among other actions, might release arachidonic acid by activating phospholipases A2. Indeed, we have detected a phosphatidic acid-specific phospholipase A2 in platelets, which might have an important role in the liberation of arachidonic acid.