title: The influence of insulin in the cell cycle of human aging cells.
abstract: Normal human IMR 90 fibroblasts at population doubling levels (PDL) 28 approximately 33 had an increased incorporation of 3H-thymidine into DNA when the cells were pretreated with physiologic concentrations of insulin (5 approximately 10 ng/ml) prior to re-initiation of the cell cycle. Insulin stimulation was not observed with fibroblasts at PDL 50 nor with SV40 virus transformed cells. In all cells treated with supra-physiologic concentrations of insulin (1000 approximately 6000 ng/ml) prior to the re-initiation of cell cycle, the incorporation of thymidine into DNA was greatly diminished. Autoradiographic studies of the effect of insulin suggest that a larger fraction of cells was found to enter S phase than untreated cultures. This effect was evident in younger cells rather than senescent cells.
mesh_terms: D001345:Autoradiography; D002453:Cell Cycle; D002470:Cell Survival; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D005347:Fibroblasts / Q000166:cytology*; D006801:Humans; D007328:Insulin / Q000502:physiology*; D013936:Thymidine / Q000378:metabolism
chemical_list: D007328:Insulin; D004247:DNA; D013936:Thymidine