Toxic and radiosensitizing effect of the 2-nitroimidazole misonidazole (Ro-07-0582) on murine CFU in vivo.

Spleen colony-forming stem cells of the bone marrow of mice (CFU) have been used as an in vivo test system for toxic and radiosensitizing effects of misonidazole. The cells were irradiated in vivo in the donors before they were suspended and injected i.v. into recipients. Hyoxic conditions were achieved by killing the donors 20 min before irradiation. A drug dose in donors of 1.0 mg/g body wt (ca 1200 microgram/ml in serum) was found to be weakly toxic over an exposure time of 50 min under hypoxic conditions. The radiosensitizing effect at this concentration was found to be about the same as the full effect of oxygen.