Y. Takahashi et al., NATIVE LIPOPROTEINS INHIBIT PLATELET ACTIVATION-INDUCED BY OXIDIZED LIPOPROTEINS, Biochemical and biophysical research communications, 222(2), 1996, pp. 453-459
Copper-catalyzed oxidation of low-density lipoproteins (LDL) (0.8 g pr
otein/l LDL, 20 mu mol/l CuSO4, 37 degrees C) resulted in the formatio
n of thiobarbituric reactive substances that was substantially complet
e at 24 hrs whereas their formation from high-density lipoproteins (HD
L) plateaued at only 25% of that amount after 8 hrs. The oxidized lipo
proteins induced aggregation and increases in [Ca2+]i in washed platel
ets, but not in platelet-rich plasma, and these activating effects wer
e not inhibited by aspirin or EGTA but were inhibited by both of the n
ative lipoproteins. These results show that oxidized HDL, like oxidize
d LDL, have platelet activating ability and suggest that the native li
poproteins may play a crucial role in preventing the oxidized lipoprot
ein-mediated platelet activation. (C) 1996 Academic Press, inc.