Evidence for a cholesteryl ester donor activity of LDL particles during alimentary lipemia in normolipidemic subjects

Postprandial hypertriglyceridemia represents an independent risk factor for coronary artery disease. In the postprandial state, elevated levels of tri glyceride-rich lipoproteins (TRL) are minor accepters of HDL-cholesteryl es ter (CE) transferred by CETP in normolipidemic subjects: indeed, LDL partic les represent the major CE accepters. In order to evaluate further the pote ntial atherogenicity of lipoprotein particles characteristic of the postpra ndial phase in normolipidemic subjects, we determined the quantitative and qualitative features of apoB- and apoA1-containing lipoproteins over an 8-h period following consumption of a mixed meal. During postprandial lipemia, we observed a significant decrease (- 12%) in plasma AI concentration (138 +/- 4 and 156 +/- 4 mg/dl, at 3 h and baseline, respectively, P < 0.005). Concomitantly, a progressive increase (+ 13%) was detected in HDL2 concentr ations (138 +/- 7 mg/dl at 4 h vs. 122 + 12 mg/dl at baseline, P < 0.005), as well as a significant reduction (- 9%) in HDL3 levels (137 + 6 mg/dl at 3 h vs. 150 +/- 4 mg/dl at baseline; P < 0.05:). Additionally, plasma LDL w as reduced by 5% (247 +/- 12 mg/dl at 3 h vs. 260 +/- 15 mg/dl at baseline; P < 0.05) 3 h following meal intake. Moreover, a significant reduction (- 10%) occurred in the CE/TG ratio in LDL at 2 h postprandially (8 +/- 2 at 2 h vs. 9 + 3 at baseline; P < 0.005). These changes reflected an increment (17 3 mg/dl at 3 h vs. 15 +/- 4 mg/dl at baseline; P < 0.05) in LDL triglyc eride concentrations. Despite the high CE acceptor capacity of LDL particle s, no measurable increase in their CE content was detected during the postp randial phase. We demonstrated that CE accepted by LDL particles from T-IDL are secondarily transferred to chylomicrons by CETP. As chylomicrons displ ayed a 260-fold lower CE/TG ratio than LDL (0.03:1 and 7.8:1 in chylomicron s and LDL, respectively), CE-rich LDL may act to donate CE to chylomicrons. In conclusion, our data indicate that the presence of elevated levels of c hylomicrons induces LDL to act as a secondary donor of CE during the postpr andial phase. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.