Diffusion mechanism of the radioprotective action of nitrogen under pressure

Abstract

The radioprotective effect of compressed nitrogen (20 atm) added to air is decreased when respiration of bean seedlings is reduced by cold treatment (+2°C), by the action of KCN or by cupferron. The effect is not observed when NO is used as a radio-sensitizer instead of air. These data contradict the adsorption hypothesis of the protective effect of inert gases and nitrogen at elevated pressure. (4–8) A diffusion hypothesis is suggested: compressed gases prevent oxygen from diffusing into intracellular spaces of the root and thus to the meristematic cells. The experiments on the infiltration of seedlings show that the vertical routes of oxygen diffusion (from the cotyledons towards the roots) are most important. In the light of this hypothesis the data on the protective action of compressed gases on other biological objects are discussed.