Figure 2.

Effect of doxycycline and minocycline on iNOS enzyme activity in RAW 264.7 cells stimulated with LPS. Murine macrophage cells (RAW 264.7) were incubated with doxycycline or minocycline (20–80 μg/ml), hydrocortisone (10 μM), or l-NMMA (75 μM) for 1 h, followed by addition of LPS at 100 ng/ml for 16–18 h. The cell-free extracts were prepared and the l-arginine → l-citrulline conversion assay was carried out in cell-free extracts. The data have been represented as specific activity of the enzyme, which was defined as pmol of citrulline per min per mg of protein. Percent inhibition represents comparison with the LPS-stimulated cells in the absence of any modulator. Data represent one of three similar experiments.