Wiggins R C
Clin Chim Acta. 1987 Feb 15;162(3):329-40. doi: 10.1016/0009-8981(87)90052-0.
Normal human urine cannot be forced through a 0.2 micron filter. To investigate the reason for this phenomenon, uromucoid (Tamm-Horsfall protein) was purified from human urine and its capacity to block a 0.2 micron Millipore filter was measured under different conditions. In the presence of cations (H+, Na+, Ca2+) uromucoid blocked the filter. The blocking varied with cation concentration. Scanning electron microscopy of the filter surface revealed different arrangements of polymerized uromucoid coating the filter surface depending on ionic conditions. In the presence of 100 mmol/l NaCl or 1 mmol/l CaCl2 uromucoid polymers were present in a fibrous arrangement. In the presence of both NaCl and CaCl2 a dense mat of uromucoid polymers was present together with clumps of aggregated polymer. In the absence of ions uromucoid formed a homogeneous coat on the filter surface (as demonstrated by scanning electron microscopy, Western blotting and 125I-uromucoid binding studies) but did not block the filter. Similar fibrous and highly aggregated arrangements of uromucoid polymer were seen in hyaline casts from urine. These data are consistent with the concept that the uromucoid glycoprotein can exist in several different polymeric forms under different ionic conditions.
正常人类尿液无法被压过0.2微米的滤器。为研究此现象的原因，从人类尿液中纯化出尿黏蛋白（Tamm-Horsfall蛋白），并在不同条件下测定其阻塞0.2微米密理博滤器的能力。在阳离子（H⁺、Na⁺、Ca²⁺）存在的情况下，尿黏蛋白会阻塞滤器。阻塞情况随阳离子浓度而变化。滤器表面的扫描电子显微镜检查显示，根据离子条件不同，覆盖在滤器表面的聚合尿黏蛋白呈现出不同的排列方式。在100 mmol/l NaCl或1 mmol/l CaCl₂存在时，尿黏蛋白聚合物呈纤维状排列。在NaCl和CaCl₂同时存在时，尿黏蛋白聚合物形成致密的垫子，同时还有聚集聚合物的团块。在无离子情况下，尿黏蛋白在滤器表面形成均匀的涂层（扫描电子显微镜、蛋白质印迹法和¹²⁵I-尿黏蛋白结合研究均证实），但不会阻塞滤器。在尿液的透明管型中也可见到类似的尿黏蛋白聚合物纤维状和高度聚集的排列。这些数据与尿黏蛋白糖蛋白在不同离子条件下可存在几种不同聚合形式的概念一致。
