Vitamin E (alpha-tocopherol) does not inhibit platelet stimulation by oxidized low density lipoprotein in vitro

Platelet-rich plasma were treated with increasing concentrations of vitamin E (alpha-tocopherol). Washed platelets were exposed to oxidized low density lipoprotein (LDL) and examined by aggregometry and electron microscopy. The treatment of washed platelets by oxidized LDL induced morphological signs of activation like pseudopodia formation and an increase in light transmission. Alpha-tocopherol in a range of 0.001-1.0 mmol had no inhibiting influences on platelet activation by oxidized LDL. These results indicate that the free radical scavenger vitamin E cannot directly inhibit platelet activation by oxidized LDL. It may be supposed that platelet activation by oxidized LDL does not occur in a radical-dependent mechanism.