Sodium-dependent, concentrative nucleoside transport in cultured intestinal epithelial cells |
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Authors: | E S Jakobs A R Paterson |
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Institution: | 1. National Center for Veterinary Drug Safety Evaluation, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;2. Beijing Key Laboratory of Detection Technology for Animal-Derived Food Safety and Beijing Laboratory for Food Quality and Safety, Beijing 100193, China |
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Abstract: | In a simple salts medium, monolayers of IEC-6 intestinal cells achieved concentrations of unmetabolized formycin B (an analog of inosine) about 6-fold higher than in the medium. Rates of formycin B influx were a saturable function of Na+ concentrations in the medium. Although IEC-6 cells possess sites with high affinity for nitrobenzylthioinosine, a potent inhibitor of equilibrative (facilitated diffusion) nucleoside transport systems in certain cell types, the inhibitor had only minor effects on formycin B uptake in IEC-6 cells, but reduced efflux of the analog from these cells. These findings indicate the joint presence in IEC-6 cells of nucleoside transporters of two types, one that is concentrative and Na+-dependent, and another that is sensitive to nitrobenzylthioinosine and apparently equilibrative. |
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