経口脂肪負荷におけるアポ蛋白B亜分画代謝

Abstract

The effects of oral fat (cream) ingestion on plasma concentrations of lipids, lipoproteins and apolipoproteins (apo) and VLDL-apo B subfractions were studied in fasted 8 healthy men aged 25-43 years (mean age: 30 years old). Cream, 200g (triglyceride 102.8g, phospholipid 7.4g, cholesterol 1.0g), was ingested within 3 minutes early in the morning. Blood was withdrawn at 0, 30, 60, 120, 180, 240 and 300 minutes after fat ingestion. Lipoproteins were fractionated by sequential ultracentrifugation. Apolipoproteins were measured by single radial immunodiffusion. Apo B subfractions in VLDL were analyzed by SDS-3-15% gradient polyacrylamide gel electrophoresis. After staining, the protein bands were evaluated at 590 nm wave length by densitometer and peak area was measured. Apo B-48 ratio (percent of apo B-48 in total apo B) was calculated.Fasting plasma concentrations of lipids and apolipoproteins were as follows: cholesterol (Ch); 184.3 ±9.0mg/dl, triglyceride (TG); 108.7±16.3mg/dl, phospholipids (PL); 197.9±5.9mg/dl, HDL-Ch; 64.3±2.4mg/dl, apo A-I; 135.5±8.5mg/dl, apo A-II; 29.8±1.2mg/dl, apo B; 72.7±5.7mg/dl, apo C-II; 3.1±0.4mg/dl, apo C-III; 8.1±0.6mg/dl, apo E; 3.7±0.1mg/dl. After fat ingestion, plasma TG increased approximately 3 times of the value before fat loading, which was mainly due to the increments of VLDL-TG and IDL-TG. Concentrations of any apolipoproteins did not show significant changes. Apo B-48 ratio increased 2 folds 60 minutes after fat loading (4.6%-8.9%) and decreased gradually to the level before fat ingestion, indicating that apo B-48 ratio is a valuable parameter to follow-up the exogenous lipoprotein metabolism. Degree of plasma lipids (especially TG) response to fat ingestion varied from subject to subject. Increment of plasma TG concentration correlated significantly with fasting plasma levels of TG (r=0.87, p<0.005), VLDL-TG (r=0.81, p<0.01), VLDL-Ch (r=0.81, p<0.01) and apo C-III (r=0.71, p<0.05), indicating that degree of TG increase after fat load is reflected in the fasting plasma levels of lipids, lipoproteins and apolipoprotein.