Regoeczi E, Debanne M T, Hatton M C, Koj A
Biochim Biophys Acta. 1978 Jul 3;541(3):372-84. doi: 10.1016/0304-4165(78)90196-4.
The capacity of the liver to eliminate asialofetuin and asialoorosomucoid was investigated in intact rats. From plasma radioactivity curve measurements and assays on tissue homogenates the liver is shown to be able to dispose of an average of 19.8 microgram of asialofetuin/min per 100 g body weight. No other major route is identified for the disappearance of asialofetuin from the plasma, although trace amounts of the protein were detectable in the urine. From analyses of the plasma radioactivity curves the elimination process for asialoorosomucoid appears to be comparatively complex because of the existence of extrahepatic disposal routes. Quantification of labelled asialoorosomucoid in liver homogenates indicates, however, that the hepatic clearance rate for asialoorosomucoid is similar to that for asialofetuin. Urinary excretion significantly contributes to the disappearance of asialoorosomucoid from the plasma but the hepatic and renal routes do not account for all the protein lost from this compartment. At plasma concentrations above the maximal eliminative capacity of the liver, the hepatic clearance of asialofetuin obeys zero-order kinetics and is remarkably constant. Elimination of a quantity of asialoglycoprotein which exceeds the calculated total number of binding sites in the liver does not reduce the efficiency of the pathway, and studies of [3H]leucine incorporation indicate that the lectin, unlike the bound asialoglycoprotein, is not destroyed in the elimination process. Cytochalasin B (80 microgram/100 g body wt.) had no measureable effect on the hepatic clearance of asialofetuin. Administration of colchicine (10 mg/100 g body wt.) resulted in transitory accumulations of asialoorosomucoid in the liver, presumably due to interference with the intracellular transport of the endocytised protein.
在完整大鼠中研究了肝脏清除去唾液酸胎球蛋白和去唾液酸血清类黏蛋白的能力。通过血浆放射性曲线测量和组织匀浆分析表明，肝脏每100克体重每分钟能够平均处理19.8微克去唾液酸胎球蛋白。虽然在尿液中可检测到痕量的该蛋白质，但未发现血浆中去唾液酸胎球蛋白消失的其他主要途径。从血浆放射性曲线分析来看，由于存在肝外清除途径，去唾液酸血清类黏蛋白的清除过程似乎相对复杂。然而，肝脏匀浆中标记的去唾液酸血清类黏蛋白的定量分析表明，去唾液酸血清类黏蛋白的肝脏清除率与去唾液酸胎球蛋白相似。尿液排泄对血浆中去唾液酸血清类黏蛋白的消失有显著贡献，但肝脏和肾脏途径并不能解释该组分中所有丢失的蛋白质。在血浆浓度高于肝脏最大清除能力时，去唾液酸胎球蛋白的肝脏清除遵循零级动力学且非常恒定。消除一定量超过肝脏中计算出的结合位点总数的去唾液酸糖蛋白不会降低该途径的效率，并且[3H]亮氨酸掺入研究表明，凝集素与结合的去唾液酸糖蛋白不同，在清除过程中不会被破坏。细胞松弛素B（80微克/100克体重）对去唾液酸胎球蛋白的肝脏清除没有可测量的影响。给予秋水仙碱（10毫克/100克体重）导致去唾液酸血清类黏蛋白在肝脏中短暂蓄积，这可能是由于干扰了内化蛋白质的细胞内转运。
