Effect of extreme hypoxia and glucose on the repair of potentially lethal and sublethal radiation damage by mammalian cells

Confluent monolayers of Chinese hamster ovary cells repaired potentially lethal x-ray damage under aerobic conditions but did not repair such damage under extremely hypoxic conditions. However, addition of extra glucose to the medium allowed some repair of potentially lethal damage by these hypoxic cells. Because of this effect of glucose, we repeated earlier experiments, which had shown that exponentially growing cells did not repair sublethal damage under extremely hypoxic conditions using both plateau-phase and exponentially growing cells. Two significant results were obtained under extremely hypoxic conditions, no repair of sublethal damage was observed, even at high glucose concentrations; under aerobic conditions, plateau-phase cells repaired sublethal damage more rapidly and more efficiently than did similarly treated exponentially growing cells. From these data we conclude that the oxygen and/or energy requirements are different for the repair of potentially lethal and sublethal damage