EFFECTS OF PB2-CELLS, ANALYSIS OF UPTAKE, TOXICITY AND INFLUENCE ON RADIOSENSITIVITY(, NI2+, HG2+ AND SE4+ ON CULTURED)

Effects of Pb2+, Ni2+, Hg2+ and Se4+ on cultured human glioma U-343MG cells were investigated considering uptake, toxicity and, in combinati on with radiation, clonogenic cell survival. The cells were exposed to 0-100 mu M of the metals for a week before the evaluation. The tests showed a tendency to toxicity with 10 mu M nickel although not signifi cant (P > 0.05). Selenium, lead and mercury exerted a significant toxi city (P < 0.05) at 2.5 mu M, 10 mu M and 1 mu M, respectively. To chal lenge the clonogenic cell survival capacity, the cells were irradiated with Co-60 photons after being exposed to the highest nontoxic concen tration of the different metals. The clonogenic cell survival tests, a fter irradiation, showed no significant change if the cells were expos ed to 5 mu M nickel, 0.5 mu M selenium or 5 mu M lead compared with th ose not exposed. Mercury, 0.1 mu M, gave a relative reduction in survi val compared with only irradiated cells of 58 +/- 17%. Thus, only merc ury affected the radiation-induced damage and/or repair. When exposed to the highest nontoxic concentrations of the different metals, the cu ltures did not display a significant uptake ratio (metal concentration ratio of exposed cells to control cells) of nickel (3.1 +/- 3.3), onl y a small uptake ratio of selenium (4.0 +/- 0.4), while there was a la rge uptake ratio of both lead (2.6 +/- 1.7) x 10(2) and mercury (1.5 /- 0.2) x 10(1). The results indicated that nickel was neither especia lly toxic nor influenced the clonogenic cell survival after irradiatio n. Mercury was more toxic and also influenced the radiation sensitivit y. Lead was taken up strongly but did not influence the radiation sens itivity. Selenium accumulated but gave no detectable effect on the rad iation sensitivity.