HDL对LDL和AcLDL渗入家兔主动脉壁的影响

本实验通过静脉注入大剂量人 HDL,人 LDL 到正常和高 Ch 血症家兔体内;大剂量人 HDL,人 AcLDL 到正常家兔体内;探讨 HDL 对 LDL 及 AcLDL 渗入家兔主动脉壁的影响。灌注大剂量~(131)I-LDL 后,各组实验兔较对照免血浆放射活性均增加,半衰期延长,高 Ch 血症尤为明显。对照兔主动脉壁标记脂蛋白渗入率:高 Ch 血症组>AcLDL 组>LDL 组。HDL 对~(131)I-LDL 及~(131)I-AcLDL 在家兔主动脉壁渗入率的影响:LDL 组减少18.660%,高 Ch 血症组减少48.280%,AcLDL 组减少63.320%。主动脉壁组织自显影显示:HDL 减少~(131)I-LDL 及~(131)I-AcLDL 渗入主动脉壁。标记脂蛋白在主动脉弓、胸腹段的渗入率,实验兔均低于对照兔。以上结果揭示主动脉内皮细胞表面有类似AcLDL 受体的存在,当 HDL 浓度异常高时可以阻止 LDL 及 AcLDL 渗入完整主动脉内皮层进入内膜。

Effect of High Density Lipoproteins on Permeability of Rabbit Aorta to Low Density Lipoproteins and Acetylated Low Density Lipoproteins

A study was made on the effect of rabbits to LDL and aectylated LDL after intravenous adminis- tration of large dose of human HDL and I-~(31)LDL to normal and hypercholesterolemia rabbits,large dose of human HDL and I-~(31)AcLDL to normal rabbits.Radioactivity of plasma in the experimental rabbits of all group is higher than that in the Control rabbits.Permeability rate of labelled lipoproteins in aorta of the control rabbits is hypercholesterolemia group>AcLDL group>LDL group.HDL decreased the per- meability rate in aorta for I-~(31)LDL on an average by 18.668% in normal rabbits,by 48.280% in hy- percholesterolemia rabbits,and for I-~(31)AcLDL on an average by 63.322% in normal rabbits.A his- toradiographic study also showed that HDL decreased the permeability of aorta wall to I-~(31)LDL in normal rabbits and particular in hypercholesterolemia rabbits,to I-~(31)AcLDL in normal rabbits.Permeability of labelled lipoproteins in the arch,thorcic and abodominal segments of aorta in the experimental rabbits is lower than that in the control rabbits.Inhibition of HDL on permeability of abodominal segment of aorta to labelled lipoproteins is greater than that of arch and thoreic sgment.The above data suggested that AcLDL receptor is presented on the surface of endothelium of aorta,when HDL at very high mo- lar concentration can hamper the transportation of LDL and AcLDL through the intact endothelium layer into the intima.