Lipid peroxidation by activated platelets: a possible link between thrombosis and atherogenesis.
Generation of reactive oxygen species (ROS) by platelets was detected by a cyano-tetrazolium dye (CTC) which forms fluorescent formazan on the cell surface upon reduction. Fluorescence was quantitated by a densitometric device. Resting platelets in plasma produced significant fluorescence (P < 0.0001), and addition of thrombin enhanced the fluorescence of the coagulated platelet mass even further (by 2 h, a 6- and 8-fold increase over fluorescence of platelet-free plasma was measured, respectively). Blood containing CTC was perfused through a glass capillary tubing and the action of shear forces resulted in the formation of an occlusive platelet thrombus. Such thrombi (formed either from whole blood or platelet-rich plasma) were intensely fluorescent, indicating formation of ROS in the platelet mass (a 10- and 8-fold increase in fluorescence over coagulated plasma, respectively). Lipid peroxide content of resting platelets in platelet-rich plasma was doubled over 24 h storage, while addition of thrombin caused a 7.4-fold increase (P < 0.0001) of lipid peroxides in the retracted platelet-rich plasma-clot. Transition metal chelator and antioxidant prevented lipid peroxidation by platelets in response to thrombin. Thrombin activation of (washed) platelets in plasma-free medium caused only 1.4-fold increase in oxidation of added low density lipoprotein (LDL). In contrast, thrombin activation of platelets suspended in de-lipidated autologous plasma resulted in a 5.25-fold increase (P < 0.0001) in LDL oxidation. Generation of ROS and lipid peroxides by platelets can be an important mechanism through which thrombotic events contribute to atherogenesis.
Gorog
P
P
Pathopharmacology Unit, William Harvey Research Institute, Medical College of St. Bartholomew's Hospital, London, UK.
Kovacs
I B
IB
D001161:Arteriosclerosis / Q000097:blood*; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D015227:Lipid Peroxidation; D008077:Lipoproteins, LDL / Q000097:blood; D008163:Luminescent Measurements; D015539:Platelet Activation; D017382:Reactive Oxygen Species; D013314:Stress, Mechanical; D013917:Thrombin / Q000494:pharmacology; D013927:Thrombosis / Q000097:blood*
D008077:Lipoproteins, LDL; D017382:Reactive Oxygen Species; D013917:Thrombin