Summary
In vitro studies suggest that oxidized low density lipoprotein inhibits fibrinolysis by stimulating the production of plasminogen activator inhibitor -1 (PAI). We assessed the effects of dietary antioxidant vitamins for four weeks on three indices of copper mediated oxidation of very low and low density lipoproteins (VLDL+LDL) and plasma fibrinolytic activities in 15 male subjects with central obesity, a condition associated with increased PAI activity. Vitamin administration resulted in a decrease in production of thiobarbituric acid reactive substances from 29.3 ± 3.9 to 13.6 ± 3.5 nmoles/mg VLDL + LDL protein (mean ± SE, p <0.003), an increase in the lag phase of conjugated diene formation from 94.8 ± 5.5 to 225.0 ±31.9 min (p <0.001) and an increase in reactivity of lysine residues from 73.6% ± 4.8% to 86.8% ± 3.6% (p <0.034) demonstrating a reduction in the susceptibility of the lipoproteins to oxidation. However, antioxidant vitamins had no effect on plasma PAI activity, PAI antigen, tissue-type plasminogen activator activity and antigen, fibrinogen and fibrin degradation products. These results do not support the hypothesis that lipoprotein oxidation is a significant cause of impaired fibrinolysis in men with central obesity.
