The authors have reported an in vivo activation of platelets associated with an increase in plasma vWF after isometric exercise in patients with ischemic heart disease (IHD). An influence of plasma lipids in this occasion was investigated using simfibrate, a derivative of clofibrate in this study.
METHODS: 1) Handgrip isometric exercise (50% of maximal voluntary contraction, 2 minutes) was loaded on 16 IHD patients, before and on simfibrate (1.5g/day P. O., 4 weeks). Platelet ADP-sensitivity and plasma VIIIR: Ag before and immediately after the exercise and serum lipids before the exercise were measured. 2) Seven hyperlipoproteinemic patients were administered with simfibrate for a long term. Platelet MDA production (Okuma et al., 1971) was meaured before and after the improvement of hyperlipoproteinemia.
RESULTS: 1) Isometric Exercise in IHD Patients: i) before simfibrate: Platelet sensitivity and VIIIR; Ag increased significantly after the exercise. ii) on simfibrate: No significant changes in platelet sensitivity and VIIIR: Ag. The abovementioned changes were prevented with simfibrate. Meanwhile, serum TC decreased and HDL-C/TC ratio increased significantly. 2) Platelet MDA in Hyperlipoproteinemic Patients: Platelet MDA production (the difference between the basal MDA value in washed platelets and the value after stimulation with thrombin) decreased after the improvement of hyperlipoproteinemia.
CONCLUSION: Platelet activation was prevented in accordance with improvement of lipid metabolism. The anti-platelet effect of simfibrate might be mediated with peroxides metabolism in platelets.
