Insulin (0.67 μM) and serum (10% v/v) stimulated hexose transport did not change with in vitro ageing of cultured human skin fibroblasts. Additionally, dexamethasone amplification of the insulin-stimulated response which yielded responses to near physiological concentrations of insulin (i.e. 6.7 nM), showed no changes with in vitro ageing. Basal (i.e. nonstimulated) hexose transport, either in the presence or absence of dexamethasone, did not change with in vitro ageing. The in vitro loss of proliferative potential during in vitro ageing of cultured human fibroblasts probably does not involve changes in short term insulin responses (e.g. stimulation of hexose transport).
