Distribution and Valence State of Radiochromium in Intracellularly Labeled Ehrlich Mouse Ascites Carcinoma Cells. ∗

Summary

1. Ehrlich mouse ascites carcinoma cells were labeled with radiochromate (Na₂Cr⁵¹O₄), and the intracellular distribution and valence state of radiochromium studied. 2. Of the total intracellular radioactivity, 71% was associated with the soluble cytoplasmic fraction; of radioactivity of this fraction, ethanol precipitated 52% with the proteins, and 46% remained in the supernate from ethanol precipitation in dialyzable form. 3. Hexavalent chromium (Cr⁵¹O₄) appeared to be intracellularly reduced to the trivalent state (Cr⁵¹⁺⁺⁺). 4. The results suggest that the cell membrane of the Ehrlich ascites tumor cell is impermeable to intracellular Cr⁺⁺⁺ ions, and that stability of the intracellular label is not dependent on protein binding alone.