Christensen E I, Maunsbach A B
Kidney Int. 1979 Sep;16(3):301-11. doi: 10.1038/ki.1979.132.
The effects of dextran on renal ultrastructure and on the handling of protein by renal proximal tubules were evaluated in dextran-tolerant rats. In vivo and in vitro systems were studied by a combination of electron microscope and cell fractionation techniques. Dextran was demonstrated by electron microscopy in endocytic vacuoles and lysosomes ing a dextran-retaining fixative, and there was an increase in the number and size of the lysosomes in the proximal tubule cells using a dextran-retaining fixative, and there was an increase in the number and size of the lysosomes in dextran-treated rats. A lysosomal accumulation of dextran was also demonstrated when 3H-dextran T-80 was injected i.v. and the renal cortex analyzed by tissue fractionation. When radioactive lysozyme was injected into dextran-treated rats, there was less filtration of the protein in the kidneys than there was in the controls, but the rate of degradation of the labeled protein in slices prepared from the renal cortex and incubated in vitro was the same in the two groups. Electron microscope autoradiography revealed that radioactive lysozyme reabsorbed by the tubule cells had a similar location in both control- and dextran-treated rats. It is concluded that lysosomal protein catabolism is not altered by the presence of dextran despite pronounced ultrastructural changes in the lysosomal system. The decreased filtration of labeled protein after dextran infusion is probably related to the decreased GFR during and immediately after the dextran infusion.
在对葡聚糖耐受的大鼠中评估了葡聚糖对肾脏超微结构以及肾近端小管蛋白质处理的影响。通过电子显微镜和细胞分级分离技术相结合的方法对体内和体外系统进行了研究。使用保留葡聚糖的固定剂，通过电子显微镜在胞吞液泡和溶酶体中证实了葡聚糖的存在，并且在使用保留葡聚糖固定剂的近端小管细胞中，溶酶体的数量和大小增加，在经葡聚糖处理的大鼠中也是如此。当静脉注射³H-葡聚糖T-80并通过组织分级分离分析肾皮质时，也证实了葡聚糖在溶酶体中的积累。当将放射性溶菌酶注射到经葡聚糖处理的大鼠体内时，与对照组相比，肾脏中蛋白质的滤过减少，但两组中从肾皮质制备并在体外孵育的切片中标记蛋白质的降解速率相同。电子显微镜放射自显影显示，小管细胞重吸收的放射性溶菌酶在对照组和经葡聚糖处理的大鼠中具有相似的定位。得出的结论是，尽管溶酶体系统存在明显的超微结构变化，但葡聚糖的存在并未改变溶酶体蛋白分解代谢。葡聚糖输注后标记蛋白质滤过减少可能与葡聚糖输注期间及输注后立即出现的肾小球滤过率降低有关。
