Fig. 6. The pathway of nitrotyrosine production in lipopolysaccharide (LPS)-treated rat lungs: Leukocyte depletion and reduced myeloperoxidase (MPO) activity reduces production of nitrotyrosine and chlorotyrosine. Nitric oxide (NO) inhalation reduces leukocyte sequestration and MPO activity, while enhancing the reaction of NO with superoxide, thereby contributing to the peroxynitrite pathway to produce nitrotyrosine. However, inhaled NO eliminated nitrotyrosine and chlorotyro-sine. Our results indicate that MPO pathway plays a role in the production of nitrotyrosine.