Growth curve and senescence associated β-gal of HUVECs exposed to chronic low-dose rates.

A) The growth curve is plotted with cumulative population doublings versus time. Growth curves of control (blue), 1.4 mGy/h (orange) and 2.4 mGy/h (green) irradiated HUVECs are shown. Cumulative population doublings from each week are presented as means ± SEM (n = 3). B) Histograms of positively-stained cells for SA-ß-gal (senescence marker) for control (blue), irradiated by 1.4 mGy/h (orange) and irradiated by 2.4 mGy/h (green). Data are presented as means ± SEM (n = 3). (Students t-test; *p<0.05, **p<0.01 and ***p<0.005).