Venkatachalam M A, Karnovsky M J, Cotran R S
J Exp Med. 1969 Aug 1;130(2):381-99. doi: 10.1084/jem.130.2.381.
Wistar/Furth rats were made nephrotic by daily administration of amino-nucleoside of puromycin, and the ultrastructural localization of horseradish peroxidase (mol wt 40,000) in the renal glomerulus was studied from 1 min to 20 hr after intravenous injection of the tracer. In control rats, peroxidase permeated the endothelial fenestrae, the basement membrane, and the epithelial slits, and was present in tubular lumina. Nephrotic glomeruli showed relatively normal basement membranes, extensive fusion of foot processes with formation of "close" intercellular junctions, and large vacuoles and pockets in epithelial cells. On serial sections some of the epithelial vacuoles communicated on one side with the extracellular space overlying basement membrane, and on the other side with the urinary space. In nephrotic animals, peroxidase permeated the basement membrane and the close junctions, and was present in many of the vacuoles and pockets as early as 1 min after injection. Only small numbers of peroxidase-positive vacuoles remained in. epithelial cells 1 hr or more after injection of the tracer. It is suggested that the epithelial pockets and vacuoles form pathways across which leaking proteins can be transferred across the epithelium into the urinary space. Epithelial vacuoles may also be absorption droplets designed to "conserve" leaking proteins, but this function was not prominent in our experiments with peroxidase.
通过每日给予嘌呤霉素氨基核苷使Wistar/Furth大鼠产生肾病，并在静脉注射示踪剂后1分钟至20小时研究辣根过氧化物酶（分子量40,000）在肾小球中的超微结构定位。在对照大鼠中，过氧化物酶透过内皮窗孔、基底膜和上皮裂隙，并存在于肾小管管腔中。肾病性肾小球显示基底膜相对正常，足突广泛融合并形成“紧密”的细胞间连接，上皮细胞中有大的空泡和小窝。在连续切片上，一些上皮空泡一侧与覆盖基底膜的细胞外空间相通，另一侧与尿空间相通。在肾病动物中，过氧化物酶在注射后1分钟就透过基底膜和紧密连接，并存在于许多空泡和小窝中。注射示踪剂1小时或更长时间后，上皮细胞中仅残留少量过氧化物酶阳性空泡。提示上皮小窝和空泡形成了通路，漏出的蛋白质可通过该通路穿过上皮进入尿空间。上皮空泡也可能是用于“保存”漏出蛋白质的吸收液滴，但在我们用过氧化物酶进行的实验中，这种功能并不突出。
