[Effects of plasma very low density lipoprotein, low density lipoprotein and high density lipoprotein on platelet aggregation in endogenous hypertriglyceridemia]

To study whether plasma very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL) were oxidatively modified in endogenous hypertriglyceridemia (HTG) and to investigate the effects of HTG VLDL, LDL and HDL on platelet aggregation in vitro.

Blood samples were taken from 21 patients with endogenous triglyceridemia and 21 normal healthy subjects; these two groups were similar in respect to age and sex. Their plasma VLDL, LDL and HDL were isolated by density gradient ultracentrifugation method, and plasma triglycerides (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDLC) were measured by enzyme method. The oxidative modification of LDL, VLDL and HDL was identified by agarose gel relative electrophoretic mobility (REM), absorbance at 234 nm (A234) and fluorescence of thiobarbituric acid reaction substances (TBARS). With the reaction system that consisted of mixed fresh normal plasma, platelet aggregation was induced by adenosine diphosphate (ADP), and the platelet maximal aggregation rate (MAR) was recorded on a 4-channel light aggregometer.

The plasma TG, TBARS levels in HTG group were 1.6 and 0.4 times over those of the control group respectively (P < 0.01). The plasma HDLC in HTG group was 32% lower than those of the control group (P < 0.01). REM, A234 and TBARS of VLDL, LDL and HDL in HTG group were significantly higher than those in the control group (P < 0.01). MAR of VLDL, LDL and HDL in HTG group were significantly higher than those in the control group (P < 0.05). The correlation analysis indicated that REM, A234 and TBARS of LDL and HDL in HTG group were positively correlated with MAR (P < 0.01).

The above data indicated that oxidative modification of plasma VLDL, LDL, HDL did occur in endogenous hypertriglyceridemia in vivo, and VLDL, LDL and HDL enhanced platelet aggregation in vitro.