Albumin fragments in normal rat urine are derived from rapidly degraded filtered albumin
Albumin fragments in normal rat urine are derived from rapidly degraded filtered albumin
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DOI：
10.1046/j.1440-1797.2003.00136.x
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发表时间：
2003-04-01
期刊：
影响因子：
2.5
通讯作者：
Comper, WD
中科院分区：
文献类型：
--
作者：
Clavant, SP;Greive, KA;Comper, WD
过滤后的白蛋白作为白蛋白衍生分子的异质性群体被排泄出来，这是由于肾通道过程中的降解造成的。为了了解这一降解过程的动力学，用放射性和放射免疫分析法研究了白蛋白在短期(分钟)和长期(7天)的清除情况。采用体积排阻色谱、体积选择性过滤和高效液相色谱对尿液中的放射性物质进行了广泛的分析。这些研究表明，在肾通过过程中，白蛋白在几分钟内降解成500-10000大小的碎片。用放射免疫分析法检测不到这些片段。放射性标记白蛋白的稳态排泄率或部分清除率发生在类似的时间段。降解速度和接近稳态清除的速度虽然很快，但比鲍曼囊和早期管腔中的分子的转运时间要慢得多。这一结果与溶酶体极快地摄取过滤后的白蛋白，以及白蛋白衍生的多肽片段在排泄前降解和回流到管腔中是一致的。
Filtered albumin is excreted as a heterogeneous population of albumin-derived molecules resulting from degradation during renal passage. In order to understand the dynamics of this degradation process, albumin clearance was studied over a short-term (minutes) and a long-term (7 days) by both radioactivity and radioimmunoassay. The radiolabelled material in the urine was also analysed extensively by using size exclusion chromatography, size selective filtration and high performance liquid chromatography. These studies demonstrate that during renal passage, albumin degradation to fragments in the size range of 500-10 000 occurs in a matter of minutes. The fragments are not detected by using radioimmunoassay. Steady state excretion rates or fractional clearance of radiolabelled albumin occur over a similar time period. Both rates of degradation and approach to steady-state clearance, while rapid, were considerably slower than the transit time for molecules in the Bowman's capsule and early tubular lumen. The results are consistent with an extremely rapid lysosomal uptake of filtered albumin, and degradation and regurgitation of the albumin-derived peptide fragments into the tubular lumen prior to excretion.