SMALL, DENSE LDL PARTICLE CONCENTRATION CORRELATES WITH PLASMINOGEN-ACTIVATOR INHIBITOR TYPE-1 (PAI-1) ACTIVITY

The relation between LDL subfractions and fibrinolytic activity was st udied in 150 men aged 53 to 63 years. Apolipoprotein B (apoB) concentr ation in the most dense LDL-5 (r = 0.39, p <0.001) and LDL-6 (r = 0.43 , p <0.001) subfractions associated with plasminogen activator inhibit or type-1 (PAI-1) activity, Subjects in the highest LDL-6 apoB tertile had higher PAI-1 (24.7 vs. 13.1 AU/ml, p <0.001) and lower t-PA (0.26 vs. 0.54 IU/ml, p <0.001) activities than men in the lowest tertile. The difference in PAI-1 remained after adjusting for either triglyceri des (p = 0.039) or insulin (p = 0.015) with cardiorespiratory fitness as an additional covariate, and history of cardiovascular disease and smoking as factors. In a regression analysis, plasma insulin and LDL-6 apoB, but not plasma triglycerides and body mass index, entered the m odel, and explained 30.6 and 3.9 % of the variance in PAI-1 activity, respectively. The novel finding of the present study was the independe nt association between small, dense LDL particles and PAI-1 activity i n middle-aged men.