Superoxide dismutase (SOD) activity in hypoxic mammalian systems.

Superoxide Dismutase (SOD) activity was compared in rabbit peritoneal macrophages (ambient PO2 approximately 15 Torr) and alveolar macrophages (ambient PO2 approximately 100 Torr) and in brain, lung, cardiac muscle, and skeletal muscle of chromically hypoxic mice(ambient PO2 approximately 50 Torr) and normoxic mice (ambient PO2 approximately 150 Torr). Peritoneal macrophages (PM) have significantly less SOD activity than alveolar macrophages (AM) (PM: 2.94 +/- 0.49 (mean +/- SD); AM:6.03 +/- 1.60 units-mg protein -1 (P less than 0.01)). SOD activity of lung and brain homogenates from the hypoxic mice was significantly less than from the normoxic controls. Heart and skeletal muscle SOD activities were not significantly different. These studies show that limitations of O2 supply are associated with reductions in SOD and are consistent with the thesis that SOD plays an important role in protection against oxygen toxicity in mammalian systems.