Radioactive Metal Complexes with Affinity for Tumors. II. Biodistribution of Radioactivity in Cellular and Subcellular Fractions of Tumor Tissues

The ^<99m>Tc and ^<57>Co complexes of ethylenediamine-N, N-diacetic acid (EDDA) are accumulated in tumor tissue. The complexes and related radioactive compounds were administered to experimental animals bearing Ehrlich tumor, and the blood, tumor, abscess, and other tissues were separated, fractionated and analyzed. In blood, the EDDA complexes of ^<99m>Tc and ^<57>Co were in dialyzable forms, whereas other tumor-nonlocalizing compounds were in undialyzable or protein-bound forms. The tumor/blood and tumor/muscle ratios of the radioactivity showed that the complexes had the high affinity for tumor tissues. Density gradient centrifugation analysis of the ascites tumor tissues showed that a significant amount of the radioactivity of the complexes was present in tumor cells. Subcellular fractionation of solid tumor tissue showed that the radioactivity was present in nuclear fraction.