ADENOSINE AND ITS RECEPTOR AGONISTS POTENTIATE NITRIC-OXIDE SYNTHASE EXPRESSION INDUCED BY LIPOPOLYSACCHARIDE IN RAW-264.7 MURINE MACROPHAGES

The effect of adenosine and its agonists on nitric oxide synthase (NOS ) activity and the production of nitrite induced by lipopolysaccharide (LPS) in RAW 264.7 cells were investigated. Nitrite production and NO S activity in the RAW 264.7 cells were increased up to 2.5 fold after co-exposure of the cells to LPS and adenosine or its agonists, as comp ared to LPS alone. Adenosine and its agonists had no effect on NOS act ivity when incubated alone with RAW 264.7 cells. Enhancement caused by adenosine or its agonists was dose-dependent but the effect was neith er A1 nor A2 receptor specific. These findings suggest that during pat hological conditions such as inflammation or trauma, the significant a mounts of cellular adenosine which are released may increase the produ ction of NO by macrophages.