Induction of Marrow Hypoxia by Radioprotective Agents
ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD
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Many compounds which possess sulfhydryl groups have been shown to protect bone marrow from radiation injury. The most effective thiol radioprotective agent is ethiofos S-2-3-aminopropylaminoethylphosphorothoic acid or WR-2721. The ability of thiol and non-thiol radioprotectors to induce hypoxia was determined using binding of 3Hmisonidazole by bone marrow cells as a measure of hypoxia. When administered at maximally radioprotective doses, four drugs WR-2721, cysteamine, 5-hydroxytryptamine, and 16,16-dimethyl prostaglandin E2 significantly increased the amount of 3Hmisonidazole bound by marrow cells, while no significant increase in binding was observed with three other agents endotoxin, AET, superoxide dimutase. Doses of WR-2721 previously shown to provide suboptimal radioprotection did not significantly increase 3H-misonidazole binding. These results suggest that the physiological effects of some radioprotectors, that is, their ability to induce marrow hypoxia, may contribute to their efficacy in vivo. Keywords Radio protective agents Reprints.