Effects of PPAR agonists on NO production in J774 macrophages. Cells were stimulated with lipopolysaccharide (LPS) and treated with increasing concentrations of fenofibrate (a), muraglitazar (b) or GW1929 (c). After 24 h incubation, nitrite accumulated into the culture medium was measured by Griess reaction as a marker of nitric oxide (NO) production. Results represent the mean + SEM (n = 6). **P <0.01 as compared to cells treated with LPS alone.