de Mendoza S G, Kashyap M L, Chen C Y, Lutmer R F
Metabolism. 1976 Oct;25(10):1143-9. doi: 10.1016/0026-0495(76)90022-6.
Intravenous administration of the aminonucleoside of puromycin produces the nephrotic syndrome (proteinuria, hypercholesterolemia, hypoproteinemia and edema) in rats. This model is very similar to human nephrotic syndrome caused by various disease states. The current study was designed to assess the nature of urinary lipoproteins in the urine of nephrotic rats, including studies related to the urinary loss of the "activator" apolipoproteins for the lipoprotein lipase-triglyceride interaction. Sprague-Dawley rats were given a single intravenous injection (10 mg/100 g) of puromycin aminonucleoside. Plasma and urine were collected before and 7, 18, 29, 36, and 53 days after injection of puromycin. Urine was fractionated in the preparative ultracentrifuge into density (d) fractions less than 1.006 (very low-density lipoproteins), d = 1.006-1.063 (low-density lipoproteins), and d = 1.063-1.210 (high-density lipoproteins--HDL). The cholesterol, triglyceride, phospholipid, and protein content of these fractions was analyzed. Lipoprotein electrophoresis was performed in agarose agar. Urine from normal and nephrotic rats was added to an in vitro system containing lipoprotein lipase and triglyceride. The free fatty acids (FFA) liberated were then measured as an index of urinary activator property on this system. Measurable urinary lipoproteins were present only on days 7 and 18 after induction of the nephrotic syndrome. Coelectrophoresis of these urinary lipoproteins with rat plasma revealed a single band having alpha- (HDL) electrophoretic mobility. The total mean protein content of day-7 urinary lipoproteins (64.3%) was greater than the content of plasma HDL (52.9%). The protein content of urinary lipoproteins also increased with time. When day-7 and day-18 postinjection urine at nephrotic rats was added to the lipoprotein lipase system, the hydrolysis of triglyceride yielded a mean of 0.320 and 0.235 muEq FFA/ml/20 min, respectively. Control rat urine yielded 0.030 muEq FFA/ml/20 min and 0.000 muEq FFA/ml/20 min 7 and 18 days after injection of normal saline, respectively. It is inferred that in this experimental model (1) high-density lipoproteins are probably excreted in the glomerular filtrate, (2) alterations in the composition of the excreted lipoproteins may occur during their passage through the nephron. The possibility that only a selective portion of the HDL spectrum is excreted into the glomerular filtrate cannot be excluded. It is suggested that the urinary or renal loss of this functionally important lipoprotein may contribute to the pathophysiology of hyperlipoproteinemia in the nephrotic syndrome.
静脉注射嘌呤霉素氨基核苷可使大鼠产生肾病综合征（蛋白尿、高胆固醇血症、低蛋白血症和水肿）。该模型与各种疾病状态引起的人类肾病综合征非常相似。本研究旨在评估肾病大鼠尿液中尿脂蛋白的性质，包括与脂蛋白脂肪酶 - 甘油三酯相互作用的“激活剂”载脂蛋白尿流失相关的研究。给Sprague-Dawley大鼠单次静脉注射（10 mg/100 g）嘌呤霉素氨基核苷。在注射嘌呤霉素之前以及注射后7、18、29、36和53天收集血浆和尿液。尿液在制备型超速离心机中分离成密度（d）小于1.006的组分（极低密度脂蛋白）、d = 1.006 - 1.063的组分（低密度脂蛋白）和d = 1.063 - 1.210的组分（高密度脂蛋白 - HDL）。分析这些组分的胆固醇、甘油三酯、磷脂和蛋白质含量。在琼脂糖凝胶中进行脂蛋白电泳。将正常大鼠和肾病大鼠的尿液加入含有脂蛋白脂肪酶和甘油三酯的体外系统中。然后测量释放的游离脂肪酸（FFA），作为该系统上尿激活剂性质的指标。仅在肾病综合征诱导后的第7天和第18天存在可测量的尿脂蛋白。这些尿脂蛋白与大鼠血浆的共电泳显示出一条具有α - （HDL）电泳迁移率的条带。第7天尿脂蛋白的总平均蛋白质含量（64.3%）高于血浆HDL的含量（52.9%）。尿脂蛋白的蛋白质含量也随时间增加。当将肾病大鼠注射后第7天和第18天的尿液加入脂蛋白脂肪酶系统时，甘油三酯的水解分别产生平均0.320和0.235 μEq FFA/ml/2０分钟。对照大鼠尿液在注射生理盐水后第7天和第18天分别产生0.030 μEq FFA/ml/2０分钟和0.000 μEq FFA/ml/2０分钟。据推断，在这个实验模型中：（１）高密度脂蛋白可能经肾小球滤过排出；（２）排出的脂蛋白在通过肾单位的过程中可能发生组成改变。不能排除只有HDL谱的选择性部分被排泄到肾小球滤液中的可能性。提示这种功能重要的脂蛋白的尿流失或肾流失可能导致肾病综合征中高脂蛋白血症的病理生理过程。
