Nitric Oxide Synthase Enzymes in the Airways of Mice Exposed to Ovalbumin: NOS2 Expression Is NOS3 Dependent

Figure 2

Exhaled NO (a) and lung lavage NO_x (b) concentrations in strains of mice exposed to filtered air or 2 weeks of OVA. NOS2${}^{-/-}$ mice exposed to filtered air have a lower exhaled NO concentration compared to C57Bl/6 mice exposed to filtered air ($2.24\pm 1.7$ ($n=15$) versus $5.12\pm 4.2$ ($n=26$) ppb, $P=.02$). Air-exposed NOS2${}^{-/-}$ mice have lower exhaled NO levels compared to air-exposed C57Bl/6 mice ($5.10\pm 0.41$ ($n=8$) versus $9.1\pm 0.7$ ($n=8$) ppb, $P<.001$). Air-exposed NOS1${}^{-/-}$ and NOS3${}^{-/-}$ also had significantly lower exhaled NO levels compared to the C57Bl/6 mice ($P<.05$). After exposure to OVA, there were no significant increases in the exhaled NO levels in any strain compared to their respective air-exposed group. C57Bl/6 mice exposed to OVA had a significant decrease in exhaled NO compared to their filtered air controls in this experiment. In contrast, lung lavage NO_x concentration (b) from NOS1${}^{-/-}$ and NOS2${}^{-/-}$ mice exposed to OVA was significantly less than C57Bl/6 mice exposed to OVA. Data are presented as means ± SEM. ${}^{*}$ denotes $P<.05\text{;}$${}^{***}P<.001$ by ANOVA.

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