EFFECT OF HYPEROXIA, HYPOXIA, AND MATURATION ON SUPEROXIDE-DISMUTASE ACTIVITY IN ISOLATED ALVEOLAR MACROPHAGES

Publisher Website
Google Scholar
Abstract
The influence of ambient O2 tensions and of cell maturation on superoxide dismutase activity were studied in tissue culture-maintained mouse alveolar macrophages. Cultivation under hyperoxic conditions (Po2 [O2 tension] about 640 mm Hg) for 24 h was associated with a significant increase in superoxide dismutase activity as compared with normoxic conditions (Po2 .apprx. 150 mm Hg). (Hyperoxia: superoxide dismutase = 7.9 .+-. 4.0 (SD); normoxia: superoxide dismutase = 4.4 .+-. 1.7 units .times. mg cell protein -1 P < 0.05.) Hypoxic exposure (Po2 .apprx. 15 mm Hg) was associated with a significant decrease in superoxide dismutase compared to normoxic controls (hypoxia: 2.2 .+-. 0.6; normoxic: 3.5 .+-. 0.6 units .times. mg protein-1 P < 0.01). This decrease was found only after 168 h of in vitro hypoxia. The in vitro maturation of alveolar macrophages cultivated in air was associated with a progressive increase in superoxide dismutase activity per 106 cells, although superoxide dismutase activity per unit protein remained constant. Molecular O2 may modify cell superoxide dismutase activity by altering intrinsic enzyme regulation. The increase in superoxide dismutase activity with hyperoxia and the decrease with hypoxia are consistent with but do not unequivocally establish an important role for superoxide dismutase in protecting against cellular O2 toxicity.

This publication has 4 references indexed in Scilit: