title: Differential effects of age on mitotically active and inactive bone marrow stem cells and splenic T cells in mice.
abstract: Young and old BALB/c mice and thymectomized young mice were subjected to continuous exposure of 6-thioguanine (6-TG), and the numbers of their bone marrow spleen colony-forming units (CFU-S) and in vitro culture colony-forming units (CFU-C) and the number and mitogen-induced proliferative activity of their splenic T cells were determined at various time intervals. The results indicated that (a) old mice have seven times more 6-TG-resistant (6-TGr) CFU-S than young mice, (b) the mitogen-induced proliferative activity of 6-TGr T cells is comparable to that of 6-TG-sensitive (6-TGs) T cells of both young and old mice, and (c) 6-TGr CFU-S and T cells are resistant to 6-TG because they are mitotically inactive and not because they are drug-resistant mutants.
mesh_terms: D000375:Aging; D000818:Animals; D001854:Bone Marrow Cells; D002454:Cell Differentiation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004351:Drug Resistance; D005260:Female; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects; D007041:Hypoxanthine Phosphoribosyltransferase / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008938:Mitosis / Q000187:drug effects; D013154:Spleen / Q000166:cytology*; D013601:T-Lymphocytes / Q000166:cytology* / Q000187:drug effects; D013866:Thioguanine / Q000494:pharmacology; D013934:Thymectomy
chemical_list: D007041:Hypoxanthine Phosphoribosyltransferase; D013866:Thioguanine