Effect of MRSA and P. aeruginosa on arginase activity, NO synthesis, and ADMA concentrations in sheep. Each group includes 6 animals. (A) Lung homogenate was used to measure arginase activity. Plasma was collected over time to measure (B) the products of nitric oxide, nitrates and nitrites (NOx), and (C) ADMA concentrations. Data are shown as means ± SEM. †P < 0.05 versus uninjured sham animals, *P < 0.05 versus MRSA.