HYPERBARIC-OXYGEN AND HYPOXIA ALTER PRODUCTION OF NITRIC-OXIDE BY J774 MURINE MACROPHAGES

This study examined changes in production of nitric oxide (NO) by cult ured macrophages (M Phi) exposed to increased oxygen tensions during c hanges in hyerbaric oxygen (HBO) treatments. Experiments were conducte d using the murine macrophage cell line J774 which was stimulated with gamma-interferon (gamma-INF) and lipopolysaccharide (LPS). Control ce lls, incubated in pO(2) = 20mmHg or 40mmHg, produced significantly (P less than or equal to 0.0001) less NO (49.2 +/- 2.6% and 41.1 +/- 2.1% respectively) than did cells exposed to 95% room air (RA), 5% CO2. Ce lls incubated in pO(2) = 20mmHg or 40mmHg, and intermittently exposed to HBO (12 PSIg) significantly (P less than or equal to 0.0001) increa sed production of NO when compared to their untreated control cells (1 48.75 +/- 18% and 101.75 +/- 6.3% respectively). Cells incubated in 95 % RA and treated with HBO showed little increase in production of NO ( 11.4 +/- 11.4%) when compared to control cells. There was no significa nt difference in production of NO when comparing HBO-treated cells tha t were incubated with different oxygen tensions; however, cells that w ere incubated with pO(2) = 20mmHg and treated with HBO produced slight ly more NO (13.5 +/- 9.2%) than did HBO-treated cells that were incuba ted with 95% RA. These data show that (1) J774 murine M Phi exposed to relatively low oxygen tensions, produce less NO than do those which a re incubated in 95% room air, and that (2) production of NO is augment ed when these cells are intermittently exposed to HBO.