Utilization of oxygen by transplanted tumors in vivo.

A tumor preparation was used which permitted the determination in vivo of the blood flow and the arterial-venous difference in oxygen content. Walker Carcinoma 256, Hepatoma 5123, and Fibrosarcoma 4956 transplanted in rats were able to remove about 50% of the oxygen carried by the afferent blood. The removal was as efficient as that of normal tissues. The oxygen consumptions in vivo were, respectively, 3.3, 5.3, and 1.0 µl/hr/mg dry weight and the RQ values were 1.25, 1.0 and 0.76. During an acute shortage of oxygen produced by anemia, the neoplastic tissues were unable to increase their blood supply; carbon dioxide elimination consistently increased; the oxygen removal ratios from blood were improved in most of the cases but the overall utilization of oxygen decreased. During a chronic shortage of oxygen, due to anemia or low blood flow, the oxygen removal ratios remained around 50% and the oxygen consumption and the carbon dioxide elimination decreased in proportion to the oxygen available. When more oxygen was supplied to carcinomas, the oxygen removal ratio remained about 50% and the consumption increased. The capacity of these tumors to utilize oxygen could not be saturated in vivo under our experimental conditions.