Christensen E I
Cell Tissue Res. 1986;243(1):101-8. doi: 10.1007/BF00221857.
The present study was performed to investigate whether membrane recycling via the dense apical tubules in cells of renal proximal tubules could be modified after exposure to large amounts of cationized ferritin. Proximal tubules in the rat kidney were microinfused in vivo with cationized ferritin for 10 or 30 min and then fixed with glutaraldehyde by microinfusion, or proximal tubules were microinfused with ferritin for 30 min and then fixed 2 h thereafter. The tubules were processed for electron microscopy, and the surface density and the volume density of the different cell organelles involved in endocytosis were determined by morphometry. The morphometric analyses showed that after loading of the endocytic vesicles with ferritin the surface density of dense apical tubules decreased to about 50% of the original value. However, 2 h later when ferritin had accumulated in the lysosomes the surface density of dense apical tubules had returned to control values. Furthermore, cationized ferritin was virtually absent from the Golgi region, indicating that the Golgi apparatus in these cells does not participate in membrane recycling. In conclusion, the present study shows that membrane recycling in renal proximal tubule cells can in part be inhibited by loading the endocytic vacuoles with ferritin.
本研究旨在探讨肾近端小管细胞中通过致密顶端小管进行的膜循环在暴露于大量阳离子化铁蛋白后是否会发生改变。将阳离子化铁蛋白在体内微量注入大鼠肾脏的近端小管10或30分钟，然后通过微量注入用戊二醛固定，或者将铁蛋白微量注入近端小管30分钟，然后在2小时后固定。对小管进行电子显微镜处理，并通过形态计量学确定参与内吞作用的不同细胞器的表面密度和体积密度。形态计量学分析表明，在用铁蛋白装载内吞小泡后，致密顶端小管的表面密度降至原始值的约50%。然而，2小时后当铁蛋白在溶酶体中积累时，致密顶端小管的表面密度已恢复到对照值。此外，阳离子化铁蛋白在高尔基体区域几乎不存在，表明这些细胞中的高尔基体不参与膜循环。总之，本研究表明，用铁蛋白装载内吞液泡可部分抑制肾近端小管细胞中的膜循环。
