Hypochlorite modified LDL are a stronger agonist for platelets than copperoxidized LDL

Experimental low density lipoprotein (LDL) oxidation is usually performed u sing trace copper, although the in vive relevance of this method has been c alled into question. Such LDL augment adenosine 5'-diphosphate (ADP) induce d platelet aggregation, presumably by the action of lipid derived compounds . In striking contrast, we find that LDL oxidized to a comparable extent by hypochlorite, an in vive occurring oxidant, reveal themselves to be potent promoters of platelet aggregation. Interestingly, hypochlorite modified LD L seem to mediate their influence on human platelets by means of the modifi ed apolipoprotein B-100 (apoB) moiety. Also, the finding that hypochlorite modified albumin is able to trigger platelet aggregation suggests an essent ial role for hypochlorite modified protein(s) in the process of platelet ac tivation. (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.