Effect of glucocorticoids on nitrite accumulation andl-[3H]arginine uptake in rat AMΦ cultured in the absence or presence of LPS
| Dexamethasone | |||
|---|---|---|---|
| 0 | 0.1 | 1 | |
| μM | |||
| Nitrite accumulation (nmol/106cells) 6-h incubation after 20-h culture | |||
| Controls | 1.1 ± 0.1 | 1.0 ± 0.1 | 0.8 ± 0.1* |
| LPS | 17.4 ± 0.8 | 9.6 ± 0.6** | 7.9 ± 0.5** |
| LPS + 1 μM mifepristone | n.d. | 15.7 ± 0.3## | 12.8 ± 0.7## |
| l-[3H]arginine uptake (% of controls) 2-min uptake after 20-h culture | |||
| Controls | 100.0 ± 1.1 | 72.2 ± 13.6** | 55.9 ± 3.8** |
| LPS | 279.4 ± 8.8 | 178.4 ± 11.8** | 150.7 ± 8.5** |
| LPS + 1 μM mifepristone | n.d. | 298.2 ± 29.1## | 220.0 ± 34.0# |
AMΦ (106 cells/well) were cultured for 20 h in the absence (controls) or presence of 1 μg/ml LPS, mifepristone, and dexamethasone at the indicated concentrations. Thereafter, the medium was removed and the cells were used forl-[3H]arginine uptake studies (for details seeExperimental Procedures). In parallel, AMΦ were additionally incubated for 6 h in Krebs-HEPES solution containing 100 μM l-arginine, and nitrite accumulated in the solution was measured. Data are expressed in absolute values for nitrite accumulation or as a percentage of the controls of the respective cell preparation for l-[3H]arginine uptake. Given are means ± S.E.M. of 6 to 27 experiments.* P < .05 and ** P< .001 compared with respective value in the absence of dexamethasone;# P < .05 and ## P< .001 compared with the respective value in the absence of mifepristone.
n.d., not determined.