CONSIDERATION of various isolated reports in the literature has led us to the hypothesis that oxygen poisoning and radiation injury have at least one common basis of action, possibly through the formation of oxidizing free radicals. This article reviews the pertinent material that led to this hypothesis and also presents the supporting evidence obtained from (i) experiments on the protective action against oxygen poisoning by substances of varied chemical nature known to increase resistance to irradiation, and (ii) experiments on the survival in oxygen of mice irradiated and exposed to high oxygen tensions simultaneously or at different intervals. Concerning free-radical formation, it is generally believed that the chemical actions of ionizing radiation on aqueous solutions are mainly indirect (1), involving the primary formation of the free radicals H' and OH" with subsequent formation of H202, atomic oxygen, and HO2' (2). In the presence of oxygen, increased amounts of the powerful and quantitatively important OH', as well as the less reactive but more persistent HG2', would be expected. Free-radical formation is also expected in normal oxidative metabolism. One mechanism by which molecular oxygen can be reduced is the compulsory univalent transfer of electrons described by Michaelis (3), according to which, in the presence of protons, one may expect the formation of OH', HO2', and H202. Daniels, et al. (4) have discussed the possible occurrence of an oxidizing free radical RO2' during the reduction of oxygen, and several other authors (5-10) have indicated the occurrence of free radicals 1 Based on work performed largely under Contract AF18-(600)556 with the
A consideration of various isolated reports in the literature has led us to the hypothesis that oxygen poisoning and radiation injury have at least one common basis of action, possibly through the formation of oxidizing free radicals. This article reviews the pertinent material that led to this hypothesis and also presents the supporting evidence obtained from (i) experiments on the protective action against oxygen poisoning by substances of varied chemical nature known to increase resistance to irradiation, and (ii) experiments on the survival in oxygen of mice irradiated and exposed to high oxygen tensions simultaneously or at different intervals.
Reproduced by permission.
R. Gerschman, D. L. Gilbert, S. W. Nye, P. Dwyer, W. O. Fenn, Oxygen Poisoning and X-irradiation: A Mechanism in Common.
Science
119
, 623-626 (1954).
Mice were exposed to various pressures of oxygen up to 10 atm. Survival times decreased abruptly between 0.7 and 1 atm. of oxygen, and reached a minimum value of 19 minutes at 10 atm. Cysteamine, reduced glutathione and thiourea had a detrimental effect at 1 or 1.5 atm. but protected mice at 6 atm. of oxygen. Cystamine and oxidized glutathione did not protect at 1 atm. but gave protection at 6 atm. of oxygen. AET (ß-aminoethylisothiuronium) gave no protection at 1 or 10 atm. but increased the survival time of mice exposed to 2 and 2.5 atm. Cobalt increased the survival time of mice exposed to 1 atm. and either exerted no influence or had a slight detrimental effect at higher oxygen pressures. Ca EDTA (calcium salt of ethylenediamintetraacetic acid) did not change the survival time of mice exposed to 6 atm. of oxygen. DEDTC (diethyldithiocarbamic acid sodium salt) increased the survival time of mice in 6 atm. of oxygen. Trihydroxyphenone antioxidants showed some protective effect against oxygen toxicity in mice exposed to 6 atm. of oxygen. The results are not inconsistent with the notion of a possible common mechanism between oxygen poisoning and x-irradiation. The action of any given agent was found to depend upon the oxygen pressure used.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.