Kinetics of uptake and macromolecular binding of Ga-67 and Fe-59 by the EMT-6 sarcoma-like tumor of BALB/c mice

In order to compare the subcellular metabolism of 67Ga and 59Fe, we have studied the EMT-6 sarcoma of BALB/c mouse, a tumor with both in-vitro and in-vivo growth forms. In-vitro 67Ga and 59Fe show similar temporal uptake profiles into exponentially growing EMT-6 cells, with a gradual increase over the first 24 hours of incubation and subsequent decine thereafter. In-vivo, 24 hours after intravenous administration of 67Ga-citrate and 59Fe-citrate to mice bearing subcutaneous EMT-6 tumors, most of the subcellular 67Ga and 59Fe is bound to discrete macromolecular components of approximate molecular weight, as follows: >250,000 MW, 80 to 90,000 MW, and 40 to 60,000 MW