Permselectivity of the glomerular capillary wall: III. Restricted transport of polyanions.
Permselectivity of the glomerular capillary wall: III. Restricted transport of polyanions.
复制标题
肾小球毛细血管壁的通透选择性：III。
作者：
R. L. Chang;W. Deen;C. Robertson;B. Brenner
白蛋白相对于菊粉的清除率大大超过了相同有效分子半径（约36A）的不带电葡聚糖的清除率，在正常缺水大鼠中分别小于0.01和0.20。白蛋白和中性右旋糖酐的清除率分数的显着差异表明，除了分子大小之外，还有一些因素阻碍了白蛋白的跨肾小球通过。由于白蛋白在生理溶液中是聚阴离子，因此我们通过将阴离子聚合物硫酸葡聚糖（每个糖基残基大约有 2.3 个硫酸基团）注入七只正常低血压慕尼黑-威斯塔大鼠体内，测试了电荷对大分子通透性的影响。对于有效半径约为 36A 的硫酸葡聚糖，清除率分数基本上降低至白蛋白的清除率（约 0.01）。相对于中性葡聚糖，硫酸葡聚糖的这种增强的限制也针对较小和较大的硫酸葡聚糖分子而被注意到。硫酸葡聚糖与葡聚糖转运的这些差异表明，肾小球毛细血管壁的某些成分（可能是覆盖肾小球上皮细胞的带负电的唾液蛋白）对带电大分子产生静电排斥。据报道，这种聚阴离子外壳的损失发生在蛋白尿疾病中，因此可能是白蛋白跨壁通道增强的原因。
The clearance of albumin relative to that of inulin is greatly exceeded by that of uncharged dextrans of the same effective molecular radius (approximately 36A), less than 0.01 vs. 0.20 in normal hydropenic rats. This marked difference in fractional clearances of albumin and neutral dextran suggests that some factor in addition to molecular size retards the transglomerular passage of albumin. Since albumin is a polyanion in physiological solution, we tested the effect of charge on macromolecular permeability by infusing the anionic polymer, dextran sulfate (approximately 2.3 sulfate groups per glycosyl residue), into seven normal hypropenic Munich-Wistar rats. For dextran sulfate with an effective radius of approximately 36A, the fractional clearance was reduced essentially to that found for albumin (approximately 0.01). This enhanced restriction of dextran sulfate, relative to neutral dextran, was also noted for smaller and larger dextran sulfate molecules. These differences in the transport of dextran sulfate vs. dextran suggest electrostatic repulsion of charged macromolecules by some component of the glomerular capillary wall, perhaps the negatively charged sialoprotein which coats glomerular epithelial cells. Loss of this polyanionic coat, as has been reported to occur in proteinuric disorders, might thereby account for the enhanced transmural passage of albumin.