Y. Tanaka, T. Sumino, K. Kawai
Feb 1, 1999
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Journal
Journal of Radioanalytical and Nuclear Chemistry
Abstract
The enhancement of cell-killing effect induced by60Co γ-rays on the aqueous solutions of potassium hexachloroplatinum(IV) (K2PtCl6) irradiated in the presence of various concentrations of NH4Cl was examined. HeLa S-3 cells were treated with the irradiated solutions for 60 minutes at 37°C, and cell survival was measured by colony forming efficiency. The mean lethal concentration (D0) for the cells treated with non-irradiated K2PtCl6 solution (1 mg/ml) was 34.5 μl/ml. However, it decreased, namely the cell-killing effect of the solution increased with increasing radiation dose up to 2.64·104 Gy in the case of 0.1M NH4Cl solution (in this condition, theD0 decreased to 9.6 μl/ml). No or only a slight enhancement was observed in the case of K2PtCl6 solutions irradiated in the presence of NaCl, (NH4)2HPO4, ammonium acetate or glycine. Observations using high performance liquid chromatography (HPLC) of irradiated K2PtCl6 solutions revealed the formation of cis- and/or trans-diaminedichloroplatinum (IV) (DDPs(IV)). However, the observed cell-killing action of the solution was too high to be explained by the amount of both the DDPs(IV) formed by γ-rays.