Oxygenation of tumors by a hemoglobin solution

Tumor oxygen tensions were measured using a computer-controlled PO2 microelectrode in two preclinical solid tumor models, the rat 9L gliosarcoma and the rat 13672 mammary carcinoma. Tumor oxygenation profiles were determined under four conditions: (a) during normal air breathing, (b) during carbogen breathing, (c) after intravenous administration of a solution of ultrapurified polymerized bovine hemoglobin with normal air breathing and (d) after intravenous administration of a solution of ultrapurified polymerized bovine hemoglobin with carbogen breathing. Both tumors had severely hypoxic regions under normal air-breathing conditions. Although carbogen breathing increased the oxygenation of the better-oxygenated portions of the tumor, it made no impact on the severely hypoxic tumor regions. Administration of the hemoglobin solution was effective in increasing the oxygenation throughout both tumors under normal air-breathing conditions. The addition of carbogen breathing to administration of the hemoglobin solution eliminated severe hypoxia in the 9L gliosarcoma and markedly reduced the severely hypoxic regions of the 13672 mammary carcinoma. At 24 h after administration of the hemoglobin solution the 13672 mammary carcinoma showed greater hypoxia than before treatment, which was partially corrected with carbogen breathing.