Sensitising effect of misonidazole on NHIK 1922 cells irradiated in vitro or as solid tumour in athymic nude mice.

Abstract

The sensitising effect of the hypoxic cell sensitiser misonidazole (MIS) on NHIK 1922 cells irradiated either as single cells in vitro or as tumours in vivo in air-breathing and in dead mice was investigated with subsequent determination of in vitro colony-forming ability. In absence of MIS no significant difference was found between the dose-response curves after irradiation of tumours in dead mice and of cells in suspension under hypoxic conditions. After irradiation of tumours in air-breathing mice the same enhancement ratio of 1.4 was found whether MIS was administered in doses of 250 or 1000 micrograms/g body weight. In dead mice the enhancement ratio was 1.3 and 2.6 after 250 and 1000 micrograms/g, respectively. The sensitising effect of MIS for cells irradiated in suspension under extremely hypoxic conditions corresponded to that found in dead mice when a comparable concentration of MIS was used.