Ficoll is not a rigid sphere
Ficoll is not a rigid sphere
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DOI：
10.1152/ajprenal.00097.2007
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发表时间：
2007-10-01
影响因子：
4.2
通讯作者：
Roy, Shuvo
中科院分区：
文献类型：
--
作者：
Fissell, William H.;Manley, Sargum;Roy, Shuvo
多分散Ficoll混合物已用于探索肾小球筛分。Ficoll似乎既不被肾小管吸收也不被肾小管分泌，因此尿Ficoll浓度仅反映肾小球滤过屏障。该文献是矛盾的关于Ficoll的行为作为一个理想化的球形溶质。Ficoll转运的进一步定义将为体内结果的解释提供信息。用FITC标记的Ficoll 70和BSA灌注包含测量为8 nm × 45 μ m的狭缝孔的均匀阵列的平板膜。分别通过凝胶渗透色谱法和Bradford测定法定量Ficoll和BSA浓度。BSA和Ficoll分子的直径等于约一半的狭缝孔宽度显示受阻运输与建模刚性球运输通过狭缝形孔。大于0.65狭缝宽度的Ficoll分子显示出超过预测的传输速率。在渗透物样品中观察到斯托克斯-爱因斯坦直径大于孔尺寸的Ficoll分子。我们目前的数据Ficoll过滤通过一个新的阵列定义明确的孔，这表明Ficoll是很好地模拟为一个理想的球体在一个大小域，但该模型打破了分子直径接近孔径。这些数据为目前关于肾小球滤过的争论提供了信息，并影响了使用Ficoll作为示踪分子得出的结论。Ficoll通过狭缝状孔的明显高渗透性表明，当使用Ficoll溶液表征膜时，需要进一步建模，包括分子的变形。
Polydisperse Ficoll mixtures have been used to explore glomerular sieving. Ficoll appears to be neither absorbed nor secreted by the renal tubule, and so urinary Ficoll concentrations reflect only the glomerular filtration barrier. The literature is contradictory regarding Ficoll's behavior as an idealized spherical solute. Further definition of Ficoll transport will inform interpretation of in vivo results. Flat-sheet membranes comprising a uniform array of slit pores measuring 8 nm by 45 mu m were perfused with FITC-labeled Ficoll 70 and BSA. Ficoll and BSA concentrations were quantified by gel-permeation chromatography and Bradford assay, respectively. BSA and Ficoll molecules with diameters equal to approximately half of the slit pore width displayed hindered transport in agreement with modeled rigid sphere transport through slit-shaped pores. Ficoll molecules larger than similar to 0.65 slit width displayed transport rates in excess of predictions. Ficoll molecules with Stokes-Einstein diameters greater than the pore dimension were observed in permeate samples. We present data for Ficoll filtration through a novel array of well-defined pores, which illustrate that Ficoll is well modeled as an ideal sphere in one size domain, but the model breaks down as molecular diameter approaches pore size. These data inform the present debate regarding glomerular filtration and affect conclusions drawn from the use of Ficoll as a tracer molecule. The apparent hyperpermeability of Ficoll through slit-shaped pores suggests that further modeling incorporating deformation of the molecule is necessary when using Ficoll solutions to characterize membranes.