Platelet arachidonic acid metabolism in severe cerebrovascular disease.

The ability of platelets to synthetise thromboxane B2 and hydroxylated fatty acids from arachidonic acid was studied simultaneously with arachidonic acid-induced aggregation in 42 patients suffering from severe cerebral atherosclerosis and also in 34 healthy controls. Additionally, phospholipase-A2-induced aggregation was performed as a probe for arachidonic acid located at the platelet surface. All the assays were performed with washed platelets, eliminating a possible influence of plasma. Platelets from patients were found responsive to significantly lower concentrations of arachidonic acid whereas thromboxane and hydroxylated fatty acid biosynthesis did not differ from controls. In the experimental conditions used, 75% of the control platelets underwent aggregation with phospholipase A2 plus sphingomyelinase C, in comparison to only 50% for the patients, indicating the necessity for further analysis of the platelet membrane lipids in atherosclerosis.