Inhibition of platelet phospholipase-A2 as a mechanism for the anti-aggregating effect of linoleic acid.

Linoleic acid was incorporated into platelet phospholipids and then released after activation of phospholipase A2 (PL-A2) with thrombin or ionophore A23187. The rate of this release was tenfold lower for linoleic than for arachidonic acid. This observation strongly suggests that incorporation of linoleic acid in platelet phospholipids might inhibit platelet PL-A2 and might explain the anti-aggregating effect of linoelic acid. In fact it has also been shown that linoleic acid inhibits PL-A2 activity at concentrations which antagonize platelet aggregation. Moreover, in experimental conditions where platelet cyclo-oxygenase is totally inhibited, aggregation does occur and can still be blocked by linoleic acid. This latter observation led to the conclusion that the anti-aggregating effect of linoleic acid is independent from prostaglandin pathway and is probably related to the phospholipid metabolism.