Hillebrant C G, Nyberg B, Einarsson K, Eriksson M
Department of Surgery, Karolinska Institute at Huddinge University Hospital, Stockholm, Sweden.
Gut. 1997 Nov;41(5):700-4. doi: 10.1136/gut.41.5.700.
The liver is a key organ in the metabolism of cholesterol in humans. It is the only organ by which substantial amounts of cholesterol are excreted from the body, either directly as free cholesterol into the bile or after conversion to bile acids. The major part of cholesterol synthesis in the body occurs in the liver. Cholesterol is also taken up by the liver from plasma lipoproteins. The relative contributions of newly synthesised cholesterol and plasma lipoprotein cholesterol to bile acid synthesis and biliary cholesterol secretion, respectively, are not known in detail.
To determine how a rapid lowering of plasma low density lipoprotein (LDL) and very low density lipoprotein (VLDL) cholesterol influences the biliary secretion rates of cholesterol and bile acids in patients with cholesterol gallstones and complete biliary drainage. In this model with a completely interrupted enterohepatic circulation, the secretion of bile acids equals the new synthesis of bile acids in the liver.
Eight patients with common bile duct stones of cholesterol type undergoing conventional cholecystectomy and choledocholithotomy.
At operation a balloon occludable Foley catheter attached to a T tube was inserted into the bile duct with the balloon placed just past the distal limb of the T tube. The T tube was allowed to drain the bile externally. One week after the operation the Foley catheter balloon was inflated, creating complete biliary drainage. Twelve hours following the inflation plasma LDL apheresis was carried out for two hours. Bile was collected for 15 minute periods starting one hour before the apheresis and ending two hours after its termination. During the collection of bile, plasma lipids were analysed on several occasions.
The plasma level of LDL cholesterol decreased by 26% from (mean (SEM)) 2.19 (0.29) to 1.63 (0.17) mmol/l during the LDL apheresis while high density lipoprotein (HDL) cholesterol in plasma was unaffected. During LDL apheresis apolipoprotein B containing lipoproteins bind to the column, causing a significant decrease of not only plasma LDL but also of VLDL cholesterol. The secretion rate of bile acids decreased significantly by 31% from 131 (38) to 90 (16) mumol/15 minutes (p = 0.045). The output of phospholipids also decreased by 19%. The biliary secretion rate of cholesterol was not, however, affected by the plasma LDL apheresis.
The results suggest that, in patients with cholesterol gallstones and complete biliary drainage, lowering of plasma LDL and VLDL cholesterol reduces the biliary secretion rate--synthesis--of bile acids without affecting the biliary secretion rate of cholesterol.
肝脏是人体胆固醇代谢的关键器官。它是唯一能使大量胆固醇从体内排出的器官，要么直接以游离胆固醇的形式排入胆汁，要么先转化为胆汁酸后再排出。体内胆固醇合成的主要部分发生在肝脏。肝脏也从血浆脂蛋白中摄取胆固醇。新合成的胆固醇和血浆脂蛋白胆固醇分别对胆汁酸合成和胆汁胆固醇分泌的相对贡献尚不清楚。
确定快速降低血浆低密度脂蛋白（LDL）和极低密度脂蛋白（VLDL）胆固醇如何影响胆固醇结石且胆汁完全引流患者的胆汁胆固醇和胆汁酸分泌率。在这个肠肝循环完全中断的模型中，胆汁酸的分泌量等于肝脏中胆汁酸的新合成量。
8例胆固醇型胆总管结石患者，接受传统胆囊切除术和胆总管切开取石术。
手术时，将连接T管的可球囊阻塞的Foley导管插入胆管，球囊置于T管远端肢体的后方。T管用于外部引流胆汁。术后1周，将Foley导管球囊充气，实现胆汁完全引流。球囊充气12小时后进行2小时的血浆LDL去除术。在去除术前1小时开始，至去除术结束后2小时，每隔15分钟收集一次胆汁。在收集胆汁期间，多次分析血浆脂质。
在LDL去除术期间，血浆LDL胆固醇水平从（均值（标准误））2.19（0.29）mmol/L降至1.63（0.17）mmol/L，降幅为26%，而血浆高密度脂蛋白（HDL）胆固醇未受影响。在LDL去除术期间，含载脂蛋白B的脂蛋白与柱结合，导致不仅血浆LDL而且VLDL胆固醇显著降低。胆汁酸分泌率从131（38）显著降低31%至90（16）μmol/15分钟（p = 0.045）。磷脂的输出量也降低了19%。然而，胆汁胆固醇分泌率不受血浆LDL去除术的影响。
结果表明，在胆固醇结石且胆汁完全引流的患者中，降低血浆LDL和VLDL胆固醇可降低胆汁酸的胆汁分泌率——合成率——而不影响胆汁胆固醇分泌率。
