RESUMO
Mice can survive lethal doses of ionizing radiation if deoxyribonucleosides or 'highly polymerized' salmon sperm DNA (Sigma) are administered 30 min to 24 h post-irradiation. DNA is more effective than deoxyribonucleosides in increasing the survival frequency. At supralethal exposures of gamma-irradiation, Deoxyribonucleosides and DNA are equally effective in reversing radiation damage which otherwise leads to chromosome breakage. The micronucleus frequencies in the polychromatic erythrocytes of bone marrow cells from DNA- or deoxyribonucleoside-treated mice were near the unirradiated control values. This reduction in chromosome breakage was approximately 4-fold when compared with the irradiated, saline-treated control. 'Highly polymerized' DNA protects against mortality if administered 48 and 24 h prior to irradiation. This is somewhat comparable to the effectiveness of the growth factors Interleukin-1 alpha (IL-1 alpha) or tumor necrosis factor-alpha (TNFalpha) administered prior to irradiation. With survival as criterion, the sensitivity of 4 lines of mice to gamma-irradiation is BALB/c > C3H/OuJ > or = C3H/HeJ > C57B1/6.
