ENHANCED ARACHIDONIC-ACID AND CALCIUM-METABOLISM IN CHOLESTERYL SULFATE-ENRICHED RAT PLATELETS

We previously found that cholesteryl sulfate (CS), a minor lipid const ituent, is present in blood platelets and might influence platelet agg regation. In this study, we investigated whether CS modifies platelet arachidonic acid and calcium metabolism. In CS-loaded rat platelets, w e found a potentiation of the arachidonate-induced aggregation, an inc rease in the thrombin-induced release of radiolabeled arachidonate pre incorporated into platelet phospholipids and an increased formation of cyclooxygenase and lipoxygenase products. In addition, the calcium up take in non-stimulated as well as in thrombin-stimulated CS-loaded pla telets was enhanced, The above-mentioned effects were never observed w ith cholesterol, cholesteryl acetate, estrone and estrone sulfate. Alt hough the precise determinants for the platelet CS concentration are n ot presently known, our findings might suggest a new role for CS as a modulator of the activity of these cells.