Role of chronic exercise in decreasing oxidized LDL-potentiated platelet activation by enhancing platelet-derived no release and bioactivity in rats

This study investigates how chronic exercise affects Ox-LDL mediated-platel et activation. Five-week-old male Wistar rats were assigned to either contr ol or trained groups. Trained rats were treadmill-trained for 10 weeks afte r familiarization. The following measurements were taken in both control ac id trained groups: plasma lipid profile, oxidation of LDL, platelet adhesiv eness, aggregability, cGMP contents, plasma and platelet-NO metabolite (nit rite plus nitrate) levels, and urinary X-iso-prostaglandin F-2 alpha (8-iso -PG F-2 alpha) levels. Based on those measurements, major findings in this study can be summarized as follows: 1) the trained group prolonged the lag time of isolated LDL subjected to copper-induced in vitro oxidation signifi cantly longer than the control group; 2) although having higher plasma and platelet derived-NO metabolite levels, the trained group had lower urinary excretion of 8-iso-PGF(2 alpha) than the control group; 3) the trained grou p had a lower platelet adhesiveness and aggregability and higher platelet d erived-NO metabolite and cGMP productions than the control group; 4) the tr ained group had a lower Ox-LDL-potentiated platelet adhesiveness and aggreg ability and Ox-LDL-attenuated NO metabolite and cGMP productions in platele t than the control group; and 5) treating the platelet with L-arginine inhi bited Ox-LDL-potentiated platelet activation in both control and trained gr oups. Results in this study demonstrate that amounts of preformed lipid per oxides decrease while NO production (which acts as an antioxidant) is signi ficantly increased after chronic exercise. Moreover, exercise training decr eases Ox-LDLpotentiated platelet activation most likely by enhancing platel et-derived NO release and bioactivity.