Correlation between Gastrointestinal Absorption and Uptake by the Critical Organ of Radioisotopes

Abstract

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 radioisotcpes.
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 ²⁰³Hg: 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 by 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 constant 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.