Division of Nephrology, Department of Medicine, Indiana Center for Biological Microscopy, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
J Am Soc Nephrol. 2012 Mar;23(3):447-57. doi: 10.1681/ASN.2011070666. Epub 2012 Jan 5.
Different laboratories recently reported incongruous results describing the quantification of albumin filtration using two-photon microscopy. We investigated the factors that influence the glomerular sieving coefficient for albumin (GSC(A)) in an effort to explain these discordant reports and to develop standard operating procedures for determining GSC(A). Multiple factors influenced GSC(A), including the kidney depth of image acquisition (10-20 μm was appropriate), the selection of fluorophore (probes emitting longer wavelengths were superior), the selection of plasma regions for fluorescence measurements, the size and molecular dispersion characteristics of dextran polymers if used, dietary status, and the genetic strain of rat. Fasting reduced the GSC(A) in Simonsen Munich Wistar rats from 0.035±0.005 to 0.016±0.004 (P<0.01). Frömter Munich Wistar rats had a much lower GSC(A) in both the fed and the fasted states. Finally, we documented extensive albumin transcytosis with vesicular and tubular delivery to and fusion with the basolateral membrane in S1 proximal tubule cells. In summary, these results help explain the previously conflicting microscopy and micropuncture data describing albumin filtration and highlight the dynamic nature of glomerular albumin permeability.
最近，不同的实验室报告了不一致的结果，描述了使用双光子显微镜对白蛋白滤过率的定量。我们研究了影响白蛋白肾小球滤过系数（GSC(A)）的因素，以解释这些不一致的报告，并制定确定 GSC(A)的标准操作规程。多种因素影响 GSC(A)，包括图像采集的肾脏深度（10-20 μm 是合适的）、荧光团的选择（发射较长波长的探针更好）、用于荧光测量的血浆区域的选择、如果使用葡聚糖聚合物的大小和分子分散特性、饮食状态和大鼠的遗传品系。禁食使 Simonsen Munich Wistar 大鼠的 GSC(A)从 0.035±0.005 降低至 0.016±0.004（P<0.01）。Frömter Munich Wistar 大鼠在禁食和进食状态下的 GSC(A)都低得多。最后，我们记录了广泛的白蛋白胞吞作用，包括囊泡和管状输送到 S1 近端肾小管细胞的基底外侧膜，并与之融合。总之，这些结果有助于解释先前描述白蛋白滤过的显微镜和微穿刺数据之间的冲突，并强调了肾小球白蛋白通透性的动态性质。
