Figure 3.

Effect of doxycycline and minocycline on the specific activity of iNOS in vitro. RAW 264.7 cells were stimulated with LPS for 16 h and cell-free extracts were prepared as a source of iNOS. Various modulators including methanol (MeOH), the carrier for N-acetylimidazole (NAI), were added 15 min prior to the addition of the cofactors to initiate the iNOS reaction. The specific activity was calculated and percent inhibition compared with the original LPS-stimulated extract; 100% specific activity was 200 pmol of citrulline per min per mg of protein. Data represent one of two similar experiments.