铁蛋白在兔肾近端小管中的穿细胞运输

TRANSCYTOSIS OF FERRITIN IN PROXIMAL TUBULES OF RABBIT

为了确定蛋白质的穿细胞转运途径，用体内显微注射技术，将阳离子铁蛋白直接注入家兔肾近端小管腔内，观察肾对蛋白质的摄取与转运。结果表明：注入铁蛋白后１５ｍｉｎ，蛋白质分子主要聚集在细胞顶部的胞吞小泡、胞吞大泡、致密顶端小管和溶酶体中。随着注入铁蛋白后时间的增加，这些蛋白质被转运到细胞底部胞质。此外，还可见一种与致密顶端小管不同的结构，直径小于０．０５μｍ，呈细管泡状，也含有铁蛋白颗粒，最初位于顶部胞质的铁蛋白运载大泡附近，可与该大泡融合，也可散在于胞质中，以后主要分布在细胞底部的胞质中。铁蛋白颗粒成簇分布在细胞侧基部间隙中，随着实验时间延长，该现象明显增加。

he protein binding in the kidney was studied in vivo by cationic ferritin microinfusion into rabbit proximal tubules. After ferritin infusion, the protein was located in the small endocytic vesicles, large endocytic vacuoles, dense apical tubules and lysosomes, initially it was in the apical part of the cells, then progressively with time it was transported to the basal part of the cells. In addition, ferritin was seen in small tubulo vesicular structures in the apical cytoplasm. These structures with a diameter of 0.03 0.05μm were often found around ferritin loaded vacuoles and occasionally connected to these vacuoles. Furthermore, small clusters of ferritin particles were found in the basolateral intercellular spaces, after tubular microinfusion of ferritin 15 min later only small amounts were observed but the number of clusters increased with time after ferritin infusion. The study demonstrates the transcytosis of protein in rabbit proximal tubules, and describes a novel ferritin containing tubulo vesicular structures.