Rada J A, Carlson E C
Pittsburgh Eye and Ear Institute, Pennsylvania.
Histol Histopathol. 1991 Apr;6(2):149-60.
Renal glomerular basement membranes (GBMs) exhibit a charge-selective barrier, comprised of anionic sites, that restrict the passage of anionic molecules into the urine. These sites are located primarily in the laminae rarae interna (LRI) and externa (LRE) of the GBM and consist of heparan sulfate proteoglycan (HSPG). Previous efforts to localize HSPG core protein within various layers of the GBM have been contradictory. In the present study when rat renal cortex blocks were treated by immersion with the cationic probe, polyethyleneimine (PEI), GBMs exhibited anionic sites concentrated primarily in the LRE and more irregularly within the LRI and lamina densa. All sites were heparitinase sensitive indicating that PEI positive sites represent negatively charged groups associated with heparan sulfate. In order to gain information on the distribution of the HSPG protein core, antibodies to HSPG from the EHS tumor matrix [anti-(EHS) HSPG] and GBMs [anti-(GBM) HSPG] were used together with immunogold to label thin sections of Lowicryl embedded kidney cortex. Depending upon the antisera used, markedly different distributions of HSPG were obtained. Immunolabelling with anti-(GBM) HSPG suggested a distribution of HSPG which was restricted to the laminae rarae, whereas labelling with anti-(EHS) HSPG indicated that the protein core penetrates through all layers of the GBM.
肾小球基底膜（GBM）呈现出一种电荷选择性屏障，由阴离子位点组成，可限制阴离子分子进入尿液。这些位点主要位于GBM的内疏松层（LRI）和外疏松层（LRE），由硫酸乙酰肝素蛋白聚糖（HSPG）组成。此前在GBM各层中定位HSPG核心蛋白的研究结果相互矛盾。在本研究中，当用阳离子探针聚乙烯亚胺（PEI）浸泡处理大鼠肾皮质组织块时，GBM的阴离子位点主要集中在LRE，在LRI和致密层中分布更不规则。所有位点对肝素酶敏感，表明PEI阳性位点代表与硫酸乙酰肝素相关的带负电荷基团。为了获取有关HSPG蛋白核心分布的信息，将来自EHS肿瘤基质的HSPG抗体[抗 -（EHS）HSPG]和GBM抗体[抗 -（GBM）HSPG]与免疫金一起用于标记Lowicryl包埋的肾皮质薄切片。根据所用抗血清的不同，获得了明显不同的HSPG分布。用抗 -（GBM）HSPG进行免疫标记表明HSPG的分布仅限于疏松层，而用抗 -（EHS）HSPG标记则表明蛋白核心穿透了GBM的所有层。
