Modulation of granuloma formation by endogenous nitric oxide.

We have studied the possible involvement of nitric oxide (NO) in granuloma formation induced by subcutaneous implantation in rats of carrageenin-soaked polyether sponges. Modulation of the L-arginine: NO pathway in rats was achieved by treating rats with the NO synthase inhibitor, NG-nitro-L-arginine methyl ester, as well as with L- or D-arginine. Granulomatous tissue formation, cell infiltration and NO2- production were reduced, in a dose-dependent manner, by NG-nitro-L-arginine methyl ester and increased by L-arginine but not by D-arginine. These results suggest that endogenous NO plays a modulating role in granuloma formation.