Majumdar Soumyajit, Macha Sreeraj, Pal Dhananjay, Mitra Ashim K
Division of Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, Kansas City, MO 64110-2499, USA.
Curr Eye Res. 2004 Aug-Sep;29(2-3):127-36. doi: 10.1080/02713680490504678.
The objective of this study was to elucidate the mechanism of ganciclovir uptake by the rabbit retina and the human retinal pigmented epithelium cell line ARPE-19.
[(3)H]Adenine, [(3)H]adenosine, [(3)H]thymidine, and [(3)H]ganciclovir were used to elucidate the mechanism of ganciclovir uptake by the ARPE-19 cell line and the isolated rabbit retinal tissue. Uptake studies using ARPE-19 cell line and isolated rabbit retina were carried out at 37 degrees C and 25 degrees C, respectively, for 5 min.
Uptake of [(3)H]adenine by ARPE-19 cells decreased by 95% in the presence of unlabeled adenine. Other nucleobases such as guanine, thymine, and uracil and the nucleosides adenosine, guanosine, thymidine, uridine, and inosine also reduced uptake of [(3)H]adenine by the ARPE-19 cells. Although [(3)H]adenosine and [(3)H]thymidine uptake was inhibited by nucleosides, nucleobases did not demonstrate any inhibitory effect, indicating that nucleosides can only bind to the nucleobase transporter but are not translocated by it. Uptake of the nucleosides and nucleobases by the ARPE-19 cells was sodium and pH independent. [(3)H]adenosine and [(3)H]thymidine uptake by the ARPE-19 cells was inhibited by nanomolar quantities of nitrobenzylthioinosine. Uptake of [(3)H]adenine by the isolated rabbit retina was drastically reduced in the presence of unlabeled adenine. Unlabeled thymidine and guanosine, and removal of sodium from the uptake medium, inhibited uptake of [(3)H]thymidine by the rabbit retina. Nucleosides, nucleobases, and unlabeled ganciclovir did not exhibit any inhibitory effect on [(3)H]ganciclovir uptake by the isolated rabbit retina or ARPE-19 cells.
Our results indicate that although the rabbit retina and the ARPE-19 cell line express nucleoside and nucleobase transporters, translocation of ganciclovir does not involve any carrier-mediated transport process. Rather, ganciclovir uptake by the rabbit retina and ARPE-19 cells is governed primarily by passive diffusion.
本研究的目的是阐明更昔洛韦被兔视网膜和人视网膜色素上皮细胞系ARPE - 19摄取的机制。
使用[³H]腺嘌呤、[³H]腺苷、[³H]胸腺嘧啶核苷和[³H]更昔洛韦来阐明ARPE - 19细胞系和分离的兔视网膜组织摄取更昔洛韦的机制。分别在37℃和25℃下对ARPE - 19细胞系和分离的兔视网膜进行摄取研究，持续5分钟。
在未标记的腺嘌呤存在下，ARPE - 19细胞对[³H]腺嘌呤的摄取减少了95%。其他核碱基如鸟嘌呤、胸腺嘧啶和尿嘧啶以及核苷腺苷、鸟苷、胸腺嘧啶核苷、尿苷和肌苷也降低了ARPE - 19细胞对[³H]腺嘌呤的摄取。虽然核苷抑制了[³H]腺苷和[³H]胸腺嘧啶核苷的摄取，但核碱基未显示出任何抑制作用，这表明核苷只能与核碱基转运体结合，但不能被其转运。ARPE - 19细胞对核苷和核碱基 的摄取不依赖于钠和pH值。纳摩尔量的硝基苄硫基肌苷抑制了ARPE - 19细胞对[³H]腺苷和[³H]胸腺嘧啶核苷的摄取。在未标记的腺嘌呤存在下，分离的兔视网膜对[³H]腺嘌呤的摄取急剧减少。未标记的胸腺嘧啶核苷和鸟苷，以及从摄取培养基中去除钠，抑制了兔视网膜对[³H]胸腺嘧啶核苷的摄取。核苷、核碱基和未标记的更昔洛韦对分离的兔视网膜或ARPE - 19细胞摄取[³H]更昔洛韦未显示出任何抑制作用。
我们的结果表明，虽然兔视网膜和ARPE - 19细胞系表达核苷和核碱基转运体，但更昔洛韦的转运不涉及任何载体介导的转运过程。相反，兔视网膜和ARPE - 19细胞对更昔洛韦的摄取主要受被动扩散控制。
