Particle size of apoB-48 carrying lipoproteins in remnant lipoproteins isolated from postprandial plasma.

Background: Particle size of apoB-48 carrying lipoproteins in remnant-like lipoprotein particles (RLP) in postprandial plasma has not been well characterized.

Methods: Plasma lipids, lipoproteins and apolipoproteins in 12 healthy subjects were analysed after an oral fat load. RLP isolated by immunoaffinity gel from plasma of a normolipidaemic and a hyperlipidaemic subject in four hours after an oral fat load was fractionated by high-performance liquid chromatography (HPLC) and monitored by total cholesterol (TC), triglycerides (TG), apoB-48 and apoB-100.

Results: TC, low-density lipoprotein (LDL)-C and apoB did not change after an oral fat load, while TG, RLP-C, RLP-TG and apoB-48 increased significantly in postprandial plasma. HPLC profiles monitored by TC and TG revealed that major lipoproteins increased in RLP after an oral fat load was VLDL size particles. The percentage of RLP-TG in total TG and the ratio of RLP-TG/RLP-C were significantly increased in four hours after an oral fat load compared with the fasting state (P < 0.01). RLP in four hours after an oral fat load fractionated by HPLC and monitored by TC, TG, apoB-48 and apoB-100 revealed that VLDL size or smaller particles were the major lipoproteins.

Conclusions: ApoB-48 carrying lipoproteins in RLP isolated from a normolipidaemic and a hyperlipidaemic subject after an oral fat load showed a similar particle size with apoB-100 carrying VLDL remnants. Therefore, the most apoB-48 carrying particles found in postprandial RLP can be classified as CM remnants. The majority of remnants in the postprandial state were not CM remnants, but VLDL remnants.