Oxygenation of the Rat 9l Gliosarcoma and the Rat 13672 Mammary Carcinoma with Various Doses of a Hemoglobin Solution

Abstract

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: 1) normal air breathing, 2) carbogen (95% O₂/5% CO₂) breathing, 3) after intravenous administration of a solution of ultrapurified polymerized bovine hemoglobin with normal air breathing and 4) 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 did not 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.