The influence of ionizing radiation on living cells’ radiation sensitivity can be affected by many parameters like dose rate, temperature, level of oxygen in irradiated system or presence of some chemicals (radioprotectors or radiosensitizers). Radioprotectors can reduce radiation sensitivity of living cells to ionizing radiation due to their high reactivity with hydroxyl radicals produced during radiolysis of water.
The aim of this work was to study the influence of various scavengers on radiation sensitivity of yeast (Saccharomyces cerevisiae, haploid strain, type a, DBM 272) under gamma irradiation of Co-60 at the dose rate and the dose 40 Gy/h and 150 Gy, respectively. Saccharomyces cerevisiae cells were cultivated on Sabouard chloramphenicol nutrient agar layer M 1067, HIMEDIA for 5 days at 30 °C. The results were gained by the counting of colonies grown up from surviving irradiated or nonirradiated cells in presence of various concentrations of the scavengers (methanol, ethanol, t-butanol, iso-butanol, n-amyl alcohol, dimethyl sulfoxide, acetone, potassium formate and DL-alanine).
The radiation protection σ was defined as a ratio of natural logarithm of surviving fraction of the cells without (s0) and with scavenger (s). The specific radiation protection k, i.e. radiation protection based on hydroxyl radical scavenging, was defined as a slope of the dependence of radiation protection σ on a scavenging efficiency Q. The scavenging efficiency Q is defined as a product of scavenger’s concentration and the reaction rate constant kOH of the reaction of hydroxyl radical with the scavenger.
It was found that the radiation protection σ of all scavengers linearly increases with increasing scavenging efficiency Q. It means that all scavengers under study act as the radioprotectors. The specific radiation protection k hyperbolically decreases with increasing rate constant kOH and it linearly rises with increasing concentration c of scavengers at the constant scavenging efficiency Q. Therefore, the radioprotection seems to be a complex process.