[Correlation between gastrointestinal absorption and uptake of radioisotopes by the critical organs]

This study was undertaken to investigate the correlation between gastrointestinal absorption of radioisotopes and uptake by the critical organ during the same period using 85Sr, 109Cd, 131I and 203Hg as radioisotopes. When the distribution of 85Sr, 109Cd, 131I and 203Hg in mice were investigated by means of the whole body autoradiography, these critical organs were determined as follows; 85Sr: bone, 109Cd: liver, 131I: thyroid gland and 230Hg: kidney. When the correlation between the injected dose and the uptake dose by the critical organ of 85Sr, 109Cd, 131I and 203Hg were investigated, uptake dose the critical organ expressed as cpm per gram of organ was in direct proportion to the injected dose and that expressed as % of the injected dose per gram of organ was held constand in either case. When the coefficient of correlation between gastrointestinal absorption and uptake by the critical organ of 85Sr, 109Cd, 131I and 203Hg were calculated, a positive correlation was revealed in either case. It is concluded from the results obtained that in vivo or in situ method, gastrointestinal absorption of radioisotopes received a support from uptake by the critical organ during the same period.