The Selective Protection of Normal Tissues by Irradiation of Tumor-Bearing Mice in Hypoxic Hypoxia

Abstract

YARMONENKO, S. P., WAINSON, A. A., BEREZNOVA, L. I., KRIMKER, V. M., OVAKIMOV, V. G., PETROSIAN, E. P., AND SHMAKOVA, N. L. The Selective Protection of Normal Tissues by Irradiation of Tumor-Bearing Mice in Hypoxic Hypoxia. Radiat. Res. 67, 447458 (1976). The possibility of selective protection of normal tissues was demonstrated when mice with solid tumors were irradiated in an atmosphere of 95% N2 and 5% 02. Irradiation of animals in this gas mixture increased their survival with a dose-modifying factor (DMF) = 2.5, decreased the number of cells with chromosomal aberration in bone marrow (DMF, 2) and the degree of hair follicle damage (DMF, 1.6). The protective effect of hypoxia drastically diminished 40 min after its application. Local irradiation of allogeneic tumors under hypoxic conditions, on the other hand, resulted in an increased rate of their regression in comparison with irradiation in air. The mechanism of the observed phenomenon is under investigation.