近端小管表面细胞膜再循环的直接证据

A DIRECT EVIDENCE FOR MEMBRANE RECYCLING OF RAT RENAL PROXIMAL TUBULE CELLS

利用大鼠活体肾小管显微穿刺技术,将一种新研制的膜蛋白标记试剂直接注入近端小管腔内,用电镜放射自显影方法处理组织切片,追踪被内陷的膜蛋白,最后体视学定量分析.结果表明:在近端小管表面细胞膜和内吞泡之间存在着有效的持续不断的片段的细胞膜循环.这提示被内陷的细胞膜可以循环回到细胞表面.同时也暗示了在大鼠肾小管细胞的表面和基底面之间存在膜结构的流动和转运.

Male Wistar rats were prepared for micropuncture, and individual proximal tubules were mi-croinfused with a new labelling reagent for detecting endocytosed membrane proteins. The tubules were fixed by perfusion with glutaraldehyde at different time interval after exposure to the reagent, and tissue specimens were processed for electron microscopic autoradiography. The present study provides one more direct evidence for the existence of an efficient and continuous recycling of intact membrane between the cell surface and the endocytic vacuoles, and demonstrates that the invaginated membrane proteins can recycle not only back to the surface but also to the brush border- Transcellular transportation was also suggested by these observations.