[Plasma HDL subfractions in endogenous hypertriglyceridemia]

Abstract

Our previous studies indicated that while the plasma triglycerides (TG) levels were significantly increased, HDL-C and apo A I levels were significantly decreased and abnormal HDL compositions were found in hypertriglyceridemic (HTG) patients. Whether the particle sizes of plasma HDL in HTG undergo a change has not yet been reported. This study was designed to observe the changes of plasma HDL subfractions in HTG patients. The plasma TG, total cholesterol (TC), HDL-C, apo A I, A II, B100, C II, C III, and E, HDL compositions and HDL subfractions--HDL2a, HDL2b, HDL3a, HDL3b and HDL3c were measured in 25 HTG patients (plasma TG > 2.26 mmol/L, TC < 6.72 mol/L) and 25 age-sex matched healthy subjects (plasma TG < 1.69 mmol/L, TC < 5.17 mmol/L). Plasma HDL was isolated by one step density gradient ultracentrifugation. Plasma and HDL TC, TC were determined by enzymatic methods; apo A I, A II, B100, C II, C III and E were measured by RID kits developed by ourselves. HDL subfractions were analyzed by a gradient gel electrophoresis method (GGE). The variation coefficients in one gel were 2.3% to 8.3% and the variation coefficients among gels were 3.5% to 9.3%. The results indicated that in the HTG group, the fasting plasma TG, apo B100, C II, C III and E levels were significantly higher (P < 0.001) and HDL-C, apo A I levels were lower (P < 0.05) as compared with those in the control group. TC in HDL in the HTG group were significantly increased (P < 0.05), while TG, apo A I, C II, C III and E were significantly decreased (P < 0.05, P < 0.01). Among HDL subfractions in the HTG group, HDL2b was significantly decreased (P < 0.02); HDL2a and HDL3a were increased (P < 0.05, P < 0.02). With the increase of plasma TG levels in the HTG group, the HDL particle sized tended to become smaller. According to the results, it is suggested that the changes of plasma HDL subfractions in HTG are related to the changes of the apolipoprotein compositions of HDL, which lead to the increase of HDL catabolism, therefore the plasma HDL2b content decreases and HDL2a, HDL3a contents increase.