NADPH Oxidase and Intermittent Hypoxia Figure 6. Changes in NADPH oxidase expression and activity. (A). Changes in P47phox mRNA expression in frontal cerebral cortex in wild type mice exposed to IH (n = 8 per experimental group; *P,0.05). (B). Changes in NADPH oxidase activity in frontal cerebral cortex in wild type mice exposed to IH (n = 8 per experimental group; *P,0.05). (C) Kinetic NADPH oxidase activities in hippocampus measured as NADPH-dependent cytochrome c reduction. Shown are representative tracings from the four experimental groups. (D) Summary of NADPH oxidase activities in hippocampus. IH resulted in a substantial increase in NOX activities in wild type mice (*P = 0.002). Such IH-induced increases of NADPH oxidase activity were much attenuated in gp91phox_/Y mice, although the increase was still significant ({P = 0.024; n = 6 for each group). doi:10.1371/journal.pone.0019847.g006 Figure 7. Lipid peroxidation was reduced in the frontal cortex of gp91phox_/Y exposed to IH. MDA tissue levels in cortex and hippocampus of gp91phox_/Y and C57BL6/J mice exposed to either room air (RA) or intermittent hypoxia for 14 days (IH). (n = 6 per experimental group; *P,0.05). doi:10.1371/journal.pone.0019847.g007 PLoS ONE | www.plosone.org 7 May 2011 | Volume 6 | Issue 5 | e19847