Kanwar Y S, Rosenzweig L J, Kerjaschki D I
Ren Physiol. 1981;4(2-3):121-30. doi: 10.1159/000172816.
Alterations in the permeability of the glomerular basement membrane (GBM) towards native ferritin (NF) and iodinated albumin (125I-BSA) following removal of the major glycosaminoglycans (GAGs) of the GBM, heparan sulfate (HS) and hyaluronic acid (HA), were assessed utilizing the techniques of routine electron microscopy and autoradiography, respectively. Kidneys were incubated with heparinase (to degrade the GAGs of the GBM) and subsequently perfused with either NF or 125I-BSA. Control kidneys, which were not treated with heparinase, showed a low permeability to both tracers, with NF being confined to the lamina rara interna and 125I-BSA exhibiting a low level of passage into the urinary spaces (as indicated by a low density of autoradiographic grains over the urinary spaces). After heparinase treatment there was an increase in the permeability of the GBM such that both NF and 125I-BSA passed through the GBM in larger quantities and entered the urinary spaces. Perfusion of cationized ferritin (CF) into control kidneys revealed this probe to bind to the HS-rich anionic sites present within the GBM. Treatment with heparinase resulted in an abolition of the CF binding thereby indicating that the sites are composed mainly of HS and that HS plays a key role in establishing the permeability properties of the GBM. The changes in the pattern of distribution and density of the anionic sites of the GBM following induction of nephrosis was also studied. Animals were rendered nephrotic by subcutaneous injections of an aminonucleoside of puromycin and their kidneys subsequently perfused with either CF or cationized cytochrome c. No difference in either the pattern of distribution on density of the anionic sites in the GBM of nephrotic kidneys was observed when compared to nonnephrotic controls; thus indicating that the proteinuria associated with aminonucleoside nephrosis might be due to changes in components of the glomerular capillary wall other than the anionic sites.
利用常规电子显微镜技术和放射自显影技术，分别评估了去除肾小球基底膜（GBM）的主要糖胺聚糖（GAG），即硫酸乙酰肝素（HS）和透明质酸（HA）后，GBM对天然铁蛋白（NF）和碘化白蛋白（125I-BSA）的通透性变化。将肾脏用肝素酶孵育（以降解GBM的GAG），随后用NF或125I-BSA灌注。未用肝素酶处理的对照肾脏对两种示踪剂的通透性较低，NF局限于内疏松层，125I-BSA进入尿腔的水平较低（尿腔上放射自显影颗粒密度较低表明了这一点）。肝素酶处理后，GBM的通透性增加，使得NF和125I-BSA都大量穿过GBM并进入尿腔。向对照肾脏灌注阳离子化铁蛋白（CF）显示该探针与GBM内存在的富含HS的阴离子位点结合。肝素酶处理导致CF结合消失，从而表明这些位点主要由HS组成，并且HS在建立GBM的通透性特性中起关键作用。还研究了肾病诱导后GBM阴离子位点的分布模式和密度变化。通过皮下注射嘌呤霉素氨基核苷使动物患肾病，随后用CF或阳离子化细胞色素c灌注它们的肾脏。与非肾病对照相比，在肾病肾脏的GBM中，阴离子位点的分布模式或密度均未观察到差异；因此表明与嘌呤霉素氨基核苷肾病相关的蛋白尿可能是由于肾小球毛细血管壁成分的变化而非阴离子位点的变化所致。
