抄録
The effect of isocaloric high and low carbohydrate diets with the same amount of cholesterol and the same P/S ratio on the properties of HDL subfractions was investigated in four normal volanteers. After three week feeding of basal diet, high and low carbohydrate diets were fed for three weeks successively. One subject was fed in the reverse order. At the end of each diet period, the plasma was obtained and HDL was prepared by ultracentrifugation. The protein and lipid composition of HDL2 and HDL3 were not different between the two diet periods. In high carbohydrate diet ingestion as compared with low carbohydrate diet ingestion:
1) HDL mass (concentration) was lower, and especially the ratio of HDL2 to HDL3 was significantly smaller. 2) HDL2 size of each subject was larger, while HDL3 size was unchanged. 3) Apo C-II and E contents in HDL2 was significantly higher. 4) Apo E/(Apo C-II+Apo C-III) ratio was significantly higher. 5) Apo C-II and Apo E contents, and Apo E/(Apo C-II+Apo C-III) ratio in HDL2 were increased in parallel with increase in HDL2 size. 6) Apo E in HDL exclusively concentrated on HDL2 fraction when HDL was fractionated by ultracentrifugation. Apo E content seemed to be closely related to the size of HDL not only in total HDL, but also in HDL2 fraction.Apo E has ability to bind to Apo E receptor of hepatocyts. Apo C-II, which is believed to inhibit the binding of lipoprotein to Apo E receptor was increased in HDL2 of high carbohydrate diet period. But the ratio of Apo E/Apo C's was increased as well as Apo E in HDL2 by high carbohydrate diet. These results suggest that decrease in HDL2 mass by high carbohydrate diet ingestion might be due to accelerated clearance of HDL2 by the liver because of absolutely and relatively increased Apo E content, and there is some possibility that increase in size of HDL2 might have preferable effect on its catabolism.
