THE LEVELS OF GLYCOSPHINGOLIPIDS, CERAMIDES, SIALIC-ACID AND GLYCOGENARE CHANGED IN PLASMA-MEMBRANES OF RAT PLATELETS HARVESTED DURING RECOVERY FROM IMMUNE-MEDIATED THROMBOCYTOPENIA

Plasma membranes of rat platelets produced at normal platelet counts a nd during early recovery from immune-mediated thrombocytopenia were ex amined for the contents of carbohydrates, lipids and glycosphingolipid s. Glucosylceramide, two monosialo-gangliosides and one disialo-gangli oside were found to be the major glycosphingolipids of platelets. Duri ng thrombocytopenia the contents of these glycosphingolipids as well a s of ceramides were several fold elevated. Among carbohydrate constitu ents of platelets and platelet plasma membranes, glycogen content was increased and that of sialic acid decreased. These results are discuss ed in the light of literature data on relevant biochemical characteris tics of megakaryocytes at different stages of maturation and on thromb opoiesis during acute experimental thrombocytopenia.