The rat 13762 mammary
carcinoma and the rat 9L
gliosarcoma were grown subcutaneously in a hind limb of female, Fisher 344 rats. The
oxygen content of the
tumors was determined using an Eppendorf pO2 histograph. Fifty-to-sixty
oxygen measurements were made per
tumor and there were 8-to-10 animals per group. The percent of pO2 readings < or = 5 mmHg in the mammary
carcinoma was 49%, this was decreased to 34% by administration of the
hemoglobin preparation (8 ml/kg) and further decreased to 29% when
carbogen (95% O2/5% CO2) breathing was added to administration of the
hemoglobin preparation. The percent of pO2 readings < or = 5 mmHg in the
gliosarcoma was 49%, this was decreased to 24% by administration of the
hemoglobin preparation and further decreased to 0% when
carbogen breathing was added to administration of the
hemoglobin preparation. Therapeutic response was assessed over a single-dose range of
radiation therapy (10, 20 and 30 Gray). The dose modifying factor produced by the
hemoglobin preparation/air was 1.6 and by the
hemoglobin preparation/
carbogen was 2.7 in the rat 13762 mammary
carcinoma. The dose modifying factor produced by the
hemoglobin preparation/air was 1.9 and by the
hemoglobin preparation/
carbogen was 2.9 in the rat 9L
gliosarcoma. Administration of a
hemoglobin-based
oxygen carrier reduced tumor hypoxia and increased
tumor response to
radiation therapy.