Rennke H G, Patel Y, Venkatachalam M A
Kidney Int. 1978 Apr;13(4):278-88. doi: 10.1038/ki.1978.41.
Glomerular permeability to horseradish peroxidase, a protein slightly smaller than rat albumin but similar in shape, was studied in Wistar-Furth rats by using a purified neutral isozyme (HRP; molecular radius, a(e) = 29.8 A) as well as an anionic succinyl-derivative (sHRP a(e) = 31.8 A) and a cationized enzyme (cHRP, a(e) = 30 A). The clearance rate of the proteins was determined over a 20-min period using the amounts of enzyme actually filtered (i.e., protein in the urine and protein reabsorbed by tubules). Fractional clearance of cationic HRP (0.338 +/- 0.019) exceeded that of neutral HRP (0.061 +/- 0.005) by a factor of 5.5 and that of anionic HRP (0.007 +/- 0.000) by a factor of 48. Tubular reabsorption was less than 10% of the filtered load. The experimental results indicate marked charge dependency of the filtration of proteins across the glomerulus. Fractional clearances for these proteins are significantly lower than those reported in the literature for dextrans of similar molecular radii. Other molecular properties such as shape and deformability may explain these differences.
通过使用纯化的中性同工酶（辣根过氧化物酶，HRP；分子半径，a(e)=29.8 Å）、阴离子琥珀酰衍生物（sHRP，a(e)=31.8 Å）和阳离子化酶（cHRP，a(e)=30 Å），研究了Wistar-Furth大鼠肾小球对辣根过氧化物酶（一种比大鼠白蛋白略小但形状相似的蛋白质）的通透性。使用实际滤过的酶量（即尿液中的蛋白质和肾小管重吸收的蛋白质）在20分钟内测定蛋白质的清除率。阳离子HRP的分数清除率（0.338±0.019）比中性HRP（0.061±0.005）高5.5倍，比阴离子HRP（0.007±0.000）高48倍。肾小管重吸收小于滤过负荷的10%。实验结果表明，蛋白质通过肾小球的滤过具有明显的电荷依赖性。这些蛋白质的分数清除率明显低于文献中报道的类似分子半径的右旋糖酐的分数清除率。其他分子特性，如形状和可变形性，可能解释了这些差异。
