The turnover of [1- 14C]eicosapentaenoic acid among individual phospholipids of human platelets

Abstract

The incorporation of [1- 14C] eicosapentaenoic acid (EPA) into the individual phospholipids of human platelets was studied using both isolated platelet suspensions and platelet-rich-plasma (PRP). With platelet suspensions, 47 and 38% of the newly-incorporated radio-activity was associated with phosphatidylcholine and phosphatidylinositol, respectively, with considerably lesser proportions residing in the phosphatidylethanolamine (8%) and phosphatidylserine (5%). A disproportionally high level of entry of [ 14C]EPA into phosphatidylinositol, relative to the minor contribution of this lipid to total platelet phospholipid was found also using PRP. Incubation of pre-labelled platelet suspensions with thrombin produced a substantial and rapid loss of [ 14C] EPA from platelet phospholipids which amounted to a net percentage (thrombin-dependent) decrease from phosphatidylinositol and phosphatidylcholine of 47 and 15%, respectively, within 1 min and 58 and 30% by 2.5 min. These results suggest a rapid turnover of EPA in human platelet phosphatidylinositol which may possibly bear relevance to the anti-aggregatory potential of this fatty acid.