Hori R, Okuda M, Ohishi Y, Yasuhara M, Takano M
Department of Pharmacy, Kyoto University Hospital, Faculty of Medicine, Japan.
J Pharmacol Exp Ther. 1992 Jun;261(3):1200-5.
Aminoglycoside antibiotics such as gentamicin are taken up by renal proximal tubular cells, yet little is known regarding the biochemical characteristics of the transport process at the cellular level. In this report, cellular handling of gentamicin was studied in the cultured kidney epithelial cell line LLC-PK1. After 2 days of incubation of the cells with gentamicin, cell-associated gentamicin decreased rapidly during the first 30 min when the cells were incubated in gentamicin-free medium, then decreased slowly. The apparent half-life of the latter phase, which should represent release from the intracellular compartment, was about 2.0 days. The rapid release of gentamicin should consist of two components, one is a release from the cell surface membrane and the other from domes. Cell surface binding of gentamicin was dependent on the ambient ionic strength. The intracellular uptake was inhibited by low temperature, neomycin, metabolic inhibitors and reagents which interact with the cytoskeleton. On the other hand, the uptake was not affected by d-glucose, organic cations and an organic anion. Thus, by estimating the intracellular gentamicin separately from the drug localized in other compartments, it is concluded that gentamicin is taken up by LLC-PK1 cells via an adsorptive endocytosis. The endocytosis of gentamicin should be dependent on metabolic energy and cytoskeletal function.
庆大霉素等氨基糖苷类抗生素可被肾近端小管细胞摄取，但在细胞水平上，关于这种转运过程的生化特性却知之甚少。在本报告中，我们在培养的肾上皮细胞系LLC-PK1中研究了庆大霉素的细胞处理情况。用庆大霉素孵育细胞2天后，当细胞在不含庆大霉素的培养基中孵育时，细胞相关的庆大霉素在最初30分钟内迅速减少，然后缓慢减少。后一阶段的表观半衰期约为2.0天，这一阶段应代表从细胞内区室释放。庆大霉素的快速释放应包括两个部分，一部分是从细胞表面膜释放，另一部分是从穹隆释放。庆大霉素的细胞表面结合取决于环境离子强度。低温、新霉素、代谢抑制剂和与细胞骨架相互作用的试剂可抑制细胞内摄取。另一方面，摄取不受d-葡萄糖、有机阳离子和有机阴离子的影响。因此，通过将细胞内庆大霉素与定位在其他区室的药物分开估计，得出结论：庆大霉素通过吸附性内吞作用被LLC-PK1细胞摄取。庆大霉素的内吞作用应依赖于代谢能量和细胞骨架功能。
