Voorschuur A H, Kuiper J, Neelissen J A, Boers W, Van Berkel T J
Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, University of Leiden, Sylvius Laboratories, The Netherlands.
Biochem J. 1994 Nov 1;303 ( Pt 3)(Pt 3):809-16. doi: 10.1042/bj3030809.
Periportal and perivenous parenchymal cells were isolated by the digitonin-pulse perfusion method. The digitonin-pulse perfusion was shown to lead to selective lysis of the correct zone with a straight and sharp border of two to three cells. The mean ratios of alanine aminotransferase activity (a marker for periportal parenchymal cells) and glutamine synthetase activity (a perivenous marker) of periportal to perivenous parenchymal cells were 1.76 and 0.025 respectively. Cells were incubated in vitro with 125I-asialo-orosomucoid (ASOR), 125I-trypsin-activated alpha 2-macroglobulin (alpha 2M-T) or 125I-beta-migrating very-low-density lipoprotein (beta-VLDL), in order to determine the zonal distribution of the asialoglycoprotein receptor (ASGPr), the alpha 2-macroglobulin receptor/low-density-lipoprotein receptor-related protein (alpha 2Mr/LRP) and the lipoprotein-remnant receptor, respectively. Maximum binding capacity for 125I-ASOR on parenchymal cells showed a periportal/perivenous ratio of 0.70. The periportal/perivenous ratio of Bmax. values of binding of 125I-alpha 2M-T to parenchymal cells was 1.51. The Bmax. values of binding of 125I-beta-VLDL, however, were about equal for both cell populations. It is concluded that the maximum binding capacity of the ASGPr on isolated periportal parenchymal cells is 0.70 times that of perivenous parenchymal cells. The 1.51-fold higher expression of the alpha 2Mr/LRP on periportal cells, compared with perivenous parenchymal cells, indicates a zonal specialization for the uptake of the suggested multiple ligands. In contrast, the observed homogeneous distribution of the lipoprotein-remnant receptor is in accordance with the suggestion that lipoprotein remnants bind to a specific receptor, which is different from the alpha 2Mr/LRP. The zonal heterogeneity in the expression of receptors suggests that receptor-dependent uptake pathways are under zonal control, leading to intrahepatic heterogeneity in the removal of ligands from the blood circulation.
采用洋地黄皂苷脉冲灌注法分离门静脉周围和肝静脉周围的实质细胞。结果表明，洋地黄皂苷脉冲灌注可导致特定区域的选择性裂解，形成两到三个细胞的笔直且清晰的边界。门静脉周围实质细胞与肝静脉周围实质细胞的丙氨酸转氨酶活性（门静脉周围实质细胞的标志物）和谷氨酰胺合成酶活性（肝静脉周围标志物）的平均比值分别为1.76和0.025。将细胞与125I-去唾液酸糖蛋白（ASOR）、125I-胰蛋白酶激活的α2-巨球蛋白（α2M-T）或125I-β迁移极低密度脂蛋白（β-VLDL）在体外孵育，以分别确定去唾液酸糖蛋白受体（ASGPr）、α2-巨球蛋白受体/低密度脂蛋白受体相关蛋白（α2Mr/LRP）和脂蛋白残粒受体的区域分布。实质细胞对125I-ASOR的最大结合能力显示门静脉周围/肝静脉周围比值为0.70。125I-α2M-T与实质细胞结合的Bmax值的门静脉周围/肝静脉周围比值为1.51。然而，125I-β-VLDL与两种细胞群体的结合Bmax值大致相等。结论是，分离的门静脉周围实质细胞上ASGPr的最大结合能力是肝静脉周围实质细胞的0.70倍。与肝静脉周围实质细胞相比，门静脉周围细胞上α2Mr/LRP的表达高1.51倍，表明在摄取所提示的多种配体方面存在区域特异性。相反，观察到的脂蛋白残粒受体的均匀分布与脂蛋白残粒与不同于α2Mr/LRP的特定受体结合的观点一致。受体表达的区域异质性表明，受体依赖性摄取途径受区域控制，导致肝脏在从血液循环中清除配体方面存在肝内异质性。
