Effects of hyperoxia on B16-F10 cells in vivo

The in vivo effects of hyperoxia were studied in lung colonies formed by B16-F10 melanoma cells in C57BL/6 mice. Several antioxidant defenses were found to change with in vivo exposure: glutathione reductase and glucose-6-phosphate dehydrogenase activities decreased as compared with levels in the cultured cells, glutathione peroxidase activity dramatically increased, and Mn-superoxide dismutase activity and levels of total glutathione were similar in vivo and in vitro. Exposure of tumor-bearing animals to 70%, O2 for 3 weeks did not alter the antioxidant defenses measured in the tumors. One hundred percent O2 exposure did not affect either initial arrest or subsequent retention of radiolabeled B16-F10 cells in the lung. Likewise, hyperoxia did not appear to alter cell division in B16-F10 cells growing in the lung. These results are consistent with our previous studies indicating that the B16-F10 cell line is resistant to levels of O2 in vivo that adversely affect other tumor cell lines.