부산대학교 도서관

Radiosensitization of hypoxic bacterial cells by five 2-nitroimidazoles, with similar reduction potentials to misonidazole but having lower lipophilicities, has been measured in Escherichia coli AB 1157 and Streptococcus lactis 712. Sensitization efficiency progressively decreased with decreasing lipophilicity in E. coli but not in S. lactis. This difference is discussed in terms of the differing membrane properties of the two bacteria; E. coli resembled a multicompartment model, as would also be expected with mammalian cells. Rapid-mix experiments are described which show that the radiosensitization observed after preirradiation contact times between ca. 3 and 30 msec is dependent on the lipophilicity of the sensitizer, higher lipophilicity resulting in a lower contact time being required for radiosensitization. This result and the observation that a highly lipophilic compound affects only half the full oxygen enhancement level after short contact times suggest that part of the sensitization process occurs in a lipophilic (membrane) compartment of the cell.