SOME OBSERVATIONS AND AN HYPOTHESIS CONCERNING THE EARLY STAGES OF RADIATION RECOVERY

Data are presented relating to the fluctuations in radiosensitivity, as determined by the acute LD/sub 50/, of two inbred strains of mice within the four days following conditioning whole-body irradiation. The kinetics of this recuperative process are typified by an initial minimum in radiosensitivity, succeeded by a rise to a maximum, terminating in a progressive return to the preirradiation level. A review of the relevant literature reveals the same kind of kinetics in other systems. It is therefore suggested that this is a general phenomenon applicable to the effects of divided doses of radiation on mammalian cell reproductive integrity. An hypothesis is proposed to account for these recuperation kinetics, based largely upon the evidence for generation phase- dependent radiosensitivity differences in division delay and survival of cell reproductive integrity. (auth)