Effect of hypochlorite (HOCl)-modified low density lipoproteins and high density lipoproteins on platelet function.

As hypochlorous acid (HOCl) might be a potential candidate for generation of modified (lipo)proteins in vivo , the present study was aimed at investigating the effects of HOCl-modified lipoproteins on platelet function in vitro. Lipoproteins modified with HOCl at concentrations that occur physiologically did not induce spontaneous platelet aggregation. However, low density lipoproteins (LDL; 100 to 500 microg protein/ml) increased platelet aggregation and fluorescence anisotropy in response to ADP (1 and 10 microM) and thrombin (0.1 and 0.5 U/ml) as well as malondialdehyde (MDA) formation as a function of increasing HOCl-concentrations (0.2 to 1.6 mM). HOCl-modified high density lipoprotein subfraction 3 (HDL3) had no effect on platelet function.