Native and oxidized low density lipoproteins enhance platelet aggregation in whole blood

The effects of native and oxidized low density lipoproteins on platelet agg regability remain controversial despite numerous studies. In the current in vestigation, effects of native, minimally and extensively copper-modified l ow-density lipoproteins on aggregation responses to ADP and collagen in pla telet-rich plasma, washed platelets, and whole blood were studied. Preincub ation with native and oxidized low-density lipoproteins(1.5-23.2 malondiald ehyde equivalents [MDAeq]/mg low density lipoprotein) did not modify aggreg ability in platelet-rich plasma or washed platelets but increased aggregati on markedly in whole blood (40-58%, p<0.01). In whole blood, the increase i n response to ADP was not affected by the degree of low-density lipoprotein oxidation. This comprehensive investigation of low density lipoprotein eff ects on platelet aggregation therefore has demonstrated that low density li poproteins indirectly increase platelet aggregability in whole blood, but n ot in platelet-rich plasma and washed platelets, presumably via an interact ion between platelets and other formed elements of blood, (C) 1999 Elsevier Science Ltd. All rights reserved.