PERMSELECTIVITY OF GLOMERULAR CAPILLARY WALL TO MACROMOLECULES .2. EXPERIMENTAL STUDIES IN RATS USING NEUTRAL DEXTRAN
PERMSELECTIVITY OF GLOMERULAR CAPILLARY WALL TO MACROMOLECULES .2. EXPERIMENTAL STUDIES IN RATS USING NEUTRAL DEXTRAN
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DOI：
10.1016/s0006-3495(75)85863-2
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发表时间：
1975-01-01
影响因子：
3.4
通讯作者：
BRENNER, BM
中科院分区：
文献类型：
--
作者：
CHANG, RLS;UEKI, IF;BRENNER, BM
为了确定肾小球毛细血管壁的渗透选择性特征，将通过凝胶色谱制备的已知分子大小的[3H]葡聚糖注入正常水合的Wistar大鼠中，从而允许同时测量鲍曼空间/血浆水（BS/P）和尿液/血浆水（U/P）浓度比，以及肾小球压力和流量。由于 (BS/P) 菊粉 = 1.01 +/- 0.01 SE(n = 34，半径=约 14 A)，并且对于分子半径范围为 21 至 35 A 的葡聚糖，(BS/P) 葡聚糖/(BS/P)菊粉等于 (U/P) 葡聚糖/(U/P)菊粉，因此这些发现证实葡聚糖既不被分泌，也不被重吸收。对于 20、24、28、32、36、40 和 44 A 的葡聚糖半径，(U/P)葡聚糖/(U/P)菊粉的平均值分别为 0.99、0.92、0.69、0.42、0.19、0.06 和 0.01。根据理论预测，这些分数右旋糖酐应随着肾小球跨毛细血管压力和流量的变化而明显变化，在这些相同的大鼠中，通过血浆容量扩张诱导的肾小球血浆流速的增加，导致除所研究的最小和最大右旋糖酐之外的所有右旋糖酐的分数清除率高度显着降低。这些发现强调，除非肾小球压力和流量也已知，否则仅分数溶质清除率不足以描述肾小球毛细血管壁的选择性渗透特性。右旋糖酐清除率对血浆流量变化的敏感性表明，右旋糖酐不仅通过整体流动而且在很大程度上通过扩散转运穿过毛细血管。
To determine the permselectivity characteristics of the glomerular capillary wall, known molecular size fractions of [3H]dextran, prepared by gel chromatography, were infused into normally hydrated Wistar rats, thus permitting simultaneous measurement of Bowman's space/plasma water (BS/P) and urine/plasma water (U/P) concentration ratios, along with glomerular pressures and flows. Since (BS/P)inulin = 1.01 +/- 0.01 SE(n = 34, radius=approximately 14 A) and since (BS/P)dextran/(BS/P)inulin equaled (U/P)dextran/(U/P)inulin for dextrans ranging in molecular radius from 21 to 35 A, these findings validate that dextrans are neither secreted nor reabsorbed. For dextran radii of 20, 24, 28, 32, 36, 40, and 44 A, (U/P)dextran/(U/P)inulin averaged 0.99, 0.92, 0.69, 0.42, 0.19, 0.06, and 0.01, respectively. In accord with theoretical predictions that these fractional dextran clearances should vary appreciably with changes in glomerular transcapillary pressures and flows, an increase in glomerular plasma flow rate, induced in these same rats by plasma volume expansion, resulted in a highly significant lowering of fractional clearance of all but the smallest and largest dextrans studied. These findings emphasize that fractional solute clearances alone are inadequate to describe the permselective properties of the glomerular capillary wall unless glomerular pressures and flows are also known. This sensitivity of fractional dextran clearance to changes in plasma flow indicates that dextrans are transported across the capillary not only by bulk flow but also to an important extent by diffusion.