THE USE OF CHROMIUM-51 AS A SENSITIVE QUANTITATIVE CRITERION OF EARLY RADIATION DAMAGE TO RAT THYMOCYTES

Abstract

The uptake of Cr61-chromate by thymocytes in suspension can be used as a sensitive quantitative criterion for the evaluation of early radiation damage to these cells, often under situations where other methods of assessing cell death such as morphological changes do not yield valid results. The development of a radiation lesion is characterized by a reduction in the uptake of Cr51, which in vitro can be detected 1 hour following irradiation and with doses as low as 25 rads. By means of this technique thymocytes have been shown to be completely protected by anoxia to doses of up to 150 rads, but at higher levels anoxia affords little protection. No protection of thymocytes could be demonstrated in vivo with S,β-aminoethylisothiouronium bromide hydrobromide (AET) or serotonin at 0.72 mmoles per kg. L-Cysteine, cysteamine, and serotonin at 1 mM concentration in vitro showed no protection of thymocytes provided they were removed from the cells immediately subsequent to irradiation.