title: Sodium-dependent, concentrative nucleoside transport in cultured intestinal epithelial cells.
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.
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D004848:Epithelium / Q000378:metabolism; D005573:Formycins / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism*; D009705:Nucleosides / Q000378:metabolism*; D051381:Rats; D012964:Sodium / Q000502:physiology*; D013868:Thioinosine / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D005573:Formycins; D009705:Nucleosides; C034561:formycin B; D013868:Thioinosine; D012964:Sodium; C001789:4-nitrobenzylthioinosine