Na(+)-dependent, active nucleoside transport in mouse spleen lymphocytes, leukemia cells, fibroblasts and macrophages, but not in equivalent human or pig cells; dipyridamole enhances nucleoside salvage by cells with both active and facilitated transport.
Formycin B influx studies have shown that P388 and L1210 mouse leukemia cells, mouse L929 cells, mouse RAW 309 Cr.1 cells, LK35.2 mouse B-cell hybridoma cells and cultured mouse peritoneal macrophages express both Na(+)-dependent, active and nonconcentrative, facilitated nucleoside transport systems. In the mouse cell lines, active transport represented only a minor nucleoside transport component and was detected only by measuring formycin B uptake in the presence of dipyridamole or nitrobenzylthioinosine, strong inhibitors of facilitated, but not of active, nucleoside transport. Inhibition of facilitated transport resulted in the concentrative accumulation of formycin B in cells expressing active nucleoside transport. Concentrative formycin B accumulation was abolished by treatment of the cells with gramicidin or absence of Na+ in the extracellular medium and strongly inhibited by ATP depletion or ouabain treatment. Mouse macrophages accumulated formycin B to 70-times the extracellular concentration in the absence of dipyridamole during 90 min of incubation at 37 degrees C. Thus active transport represents a major nucleoside transport system of these cells, similarly as previously reported for mouse spleen lymphocytes. In contrast to the various types of mouse cells, active formycin B transport was not detected in human HeLa cells, human H9, Jurkat and CEM T lymphoidal cells and pig spleen lymphocytes. These cells expressed only facilitated nucleoside transport with kinetic properties similar to those of the facilitated transporters of other mammalian cells.
Plagemann
P G
PG
Department of Microbiology, University of Minnesota Medical School, Minneapolis.
Aran
J M
JM
D000818:Animals; D001693:Biological Transport, Active; D002478:Cells, Cultured; D004176:Dipyridamole / Q000494:pharmacology*; D005347:Fibroblasts / Q000378:metabolism; D005573:Formycins / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D007939:Leukemia L1210 / Q000378:metabolism; D007941:Leukemia P388 / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism; D009705:Nucleosides / Q000378:metabolism*; D010695:Phlorhizin / Q000494:pharmacology; D012964:Sodium / Q000494:pharmacology*; D013154:Spleen / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D013552:Swine; D014407:Tumor Cells, Cultured
D005573:Formycins; D009705:Nucleosides; C034561:formycin B; D004176:Dipyridamole; D012964:Sodium; D010695:Phlorhizin