Tornvall P, Hamsten A, Carlson L A
King Gustaf V Research Institute, Karolinska Institute, Stockholm, Sweden.
Atherosclerosis. 1990 May;82(1-2):125-35. doi: 10.1016/0021-9150(90)90151-8.
Small (Sf 20-100) very low density lipoprotein (VLDL) particles were prepared by density gradient ultracentrifugation of plasma from normolipidemic and type IV hypertriglyceridemic post-infarction patients and healthy controls. The small VLDL separated from the plasma of severely hypertriglyceridemic post-infarction patients were found to contain twice the amount of cholesteryl esters per particle, compared with small VLDL from normolipidemic patients and healthy controls. There was a linear increase in the percentage of cholesterol that was esterified in the small VLDL with the serum VLDL triglyceride concentration (r = 0.66). When incubated for two hours with bovine lipoprotein lipase in excess and bovine albumin as a free fatty acid acceptor at one and the same triglyceride concentration in the medium, the end-product isolated by ultracentrifugation varied as a function of the serum VLDL triglyceride level. The amount of glyceride-glycerol recovered after two hours of incubation with lipoprotein lipase was 13.3 +/- 1.3% (mean +/- SEM) of the initial values and did not correlate with the VLDL triglyceride level. With rising serum VLDL triglyceride concentration, the product isolated in the low density lipoprotein (LDL) density region (1.006 less than d less than 1.063 kg/l) contained more total cholesterol and phospholipids. The linear correlation coefficients for these relations were 0.65 and 0.58 for cholesterol and phospholipids respectively. The ratio of total cholesterol to insoluble protein in the LDL density range after lipolysis rose with increasing serum VLDL triglyceride level (r = 0.68). The end-product was further characterized by density gradient ultracentrifugation of the incubate. In vitro LDL derived by lipolysis of normolipidemic small VLDL was denser than in vitro LDL of hypertriglyceridemic small VLDL. A significant relation was found between the percentage of cholesteryl esters of total cholesterol in the substrate and the relative amount of total cholesterol recovered in the LDL density fraction after lipolysis (r = 0.69). We suggest that the enrichment with cholesteryl esters of small VLDL from type IV hypertriglyceridemic patients is caused by lipid transfer from LDL and high density lipoprotein (HDL) and that the change in VLDL particle composition influences the precursor-product relationship to LDL.
通过对血脂正常和IV型高甘油三酯血症心肌梗死后患者以及健康对照者的血浆进行密度梯度超速离心，制备了小（Sf 20 - 100）极低密度脂蛋白（VLDL）颗粒。与血脂正常患者和健康对照者的小VLDL相比，从重度高甘油三酯血症心肌梗死后患者血浆中分离出的小VLDL每个颗粒所含胆固醇酯的量是其两倍。小VLDL中酯化胆固醇的百分比随血清VLDL甘油三酯浓度呈线性增加（r = 0.66）。当在培养基中甘油三酯浓度相同的情况下，与过量的牛脂蛋白脂肪酶和作为游离脂肪酸受体的牛白蛋白一起孵育两小时后，通过超速离心分离出的终产物随血清VLDL甘油三酯水平而变化。与脂蛋白脂肪酶孵育两小时后回收的甘油甘油量为初始值的13.3±1.3%（平均值±标准误），且与VLDL甘油三酯水平无关。随着血清VLDL甘油三酯浓度升高，在低密度脂蛋白（LDL）密度区域（1.006＜d＜1.063 kg/l）分离出的产物含有更多的总胆固醇和磷脂。这些关系的线性相关系数胆固醇为0.65，磷脂为0.58。脂解后LDL密度范围内总胆固醇与不溶性蛋白质的比率随血清VLDL甘油三酯水平升高而升高（r = 0.68）。通过对孵育物进行密度梯度超速离心进一步表征终产物。血脂正常的小VLDL经脂解产生的体外LDL比高甘油三酯血症小VLDL的体外LDL密度更高。在底物中总胆固醇的胆固醇酯百分比与脂解后LDL密度级分中回收的总胆固醇相对量之间发现显著关系（r = 0.69）。我们认为，IV型高甘油三酯血症患者小VLDL中胆固醇酯的富集是由LDL和高密度脂蛋白（HDL）的脂质转移引起的，并且VLDL颗粒组成的变化影响了与LDL的前体 - 产物关系。
