摘要：

Using a cellular fast-mixing technique, the time course of radiation sensitization of hypoxic, V79 cells by various concentrations of RSU-1069 (0·252·5 mmol dm3) and misonidazole (2·550 mmol dm3) have been studied to distinguish between fast chemical processes and the much slower biochemical responses to ionizing radiation and the monofunctional alkylating action of RSU-1069. Under conditions of equi-concentration, misonidazole and RSU-1069 show similar radiosensitizing efficiencies for pre-irradiation contact times up to 1 s. The values of the sensitizer enhancement ratio of 1·5 for both 2-nitroimidazoles (2·5 mmol dm3) is considerably less than that of 1·92·8 determined with misonidazole for a pre-irradiation contact time of 1 h under hypoxia. It is proposed that the enhanced radiosensitizing efficiency of RSU-1069 compared to that of misonidazole after long contact times involves, in part, the formation of sub-toxic damage probably involving monofunctional and/or bifunctional action of RSU-1069 prior to irradiation.

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