Distribution of phosphatidylethanolamine arachidonic acid in platelet membranes

Arachidonic acid (20 : 4) and other fatty acids and aldehydes in phosphatidylethanolamine (PE) present on the platelet surface was determined. Surface-exposed PE was isolated by using 2,4,6-trinitrobenzenesulfonate, a non-penetrating probe (Schick, P.K., Kurica, K.B. and Chacko, G.K. (1976) J. Clin. Invest. 57, 1221--1226). PE contains 50% total platelet arachidonic acid. Approx. 16% platelet PE is present on the platelet surface. The study showed that the fatty acid and aldehyde composition of PE on the platelet surface is virtually identical to that in PE present inside the platelet. Therefore, 8 nmol arachidonic acid are present in PE in the outer layer of the plasma membrane in 10(9) platelets.