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Chemotherapy of brain tumors. Uptake of tritiated methotrexate by a transplantable intracerebral ependymoblastoma in mice.

✓ The uptake and distribution in brain tumors of a parenterally administered chemotherapeutic agent were studied in mice bearing intracerebral implants of a transplantable ependymoblastoma. Tritiated methotrexate (3H-MTX) was injected intravenously, and autoradiographs of the tumors and adjacent brain were prepared at 2, 10, and 60 min after injection using a technique suitable for soluble compounds. In the tumors at 2 min the drug was mainly intravascular and interstitial while at 60 min the drug was mainly intracellular. This is the first demonstration of cellular uptake of a chemotherapeutic agent by neoplastic cells within the brain. At 60 min, almost all the cells in the central mass of the intracerebral tumors were heavily labeled. However, cells at the periphery of the mass and those infiltrating into adjacent brain showed scanty labeling. Uptake in normal brain was very low, while uptake in edematous brain adjacent to the tumors was much higher although not as high as in the tumors. The study show...