Leukotrienes do not regulate nitric oxide production in RAW 264.7 macrophages

RAW 264.7 macrophages respond to lipopolysaccharide (LPS) and interferon-gamma (IFN-gamma) by producing large amounts of nitric oxide (NO) and prostaglandin E(2) (PGE(2)), with maximal production 18-24 h after treatment. Following stimulation with the calcium inophore A23187, cultures of RAW cells also produce modest amounts of leukotrienes. However, the capacity of these cells to produce leukotrienes is transient, beginning 2 h after vehicle or LPS/IFN-gamma treatment, peaking by 4-6 h and absent by 8 h. A-79175, (R(+)N-[3-[5-(4-Fluorophenoxy)-2-furanyl]-1-methyl-2-propynyl]-N-hydroxyurea) real a specific inhibitor of 5-lipoxygenase (5-LO), abolished leukotriene production by RAW cells in a dose-dependent, non-cytotoxic fashion while having no effect on PGE(2) or NO production. By contrast, nordihydroguaiaretic acid (NDGA) inhibited production of leukotrienes, PGE(2) and NO only at doses that were cytotoxic to the RAW cells. Exogenous leukotriene B-4 (LTB(4)) had no effect on either NO or PGE(2) production. An inhibitor of NO production, L-N-5-(1-iminoethyl) ornithine HCl (NIO) also did not affect leukotriene or PGE(2) production, while dexamethasone blocked PGE(2) and NO production, but did not affect leukotriene production in these cells. Taken collectively, these results indicate that there is no interaction between the pathways for leukotriene and nitric oxide production in RAW 264.7 macrophages.