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

Figure 4

Total lung compliance in (a) C57BL/6, (b) NOS1${}^{-/-}$, (c) NOS2${}^{-/-}$, and (d) NOS3${}^{-/-}$ mice exposed to either filtered air or 2 weeks of OVA. Symbols: (blue) open triangles for filtered air exposure, (black) circles for OVA exposure. Lung compliance was measured at baseline and following serial doses (0, 0.5, 1.0, and 2.0 mg/mL) of nebulized methacholine (MCh). The slope of the MCh response for NOS2${}^{-/-}$ mice exposed to OVA ($-0.0028\pm 0.00042\text{,}$$F=43.56$) was significantly different from that of the NOS2${}^{-/-}$ mice exposed to air ($-0.0003\pm 0.00017\text{,}$$F=3.0\text{;}$$P=.005$). For NOS3${}^{-/-}$ mice, the slopes of the best fit lines for the MCh response curve for OVA-exposed mice ($-0.0005\pm 0.0002\text{,}$$F=4.627$) and filtered air-exposed mice ($-0.003\pm 0.0003\text{,}$$F=95.07$) were also different ($P=.004$). NOS3${}^{-/-}$ mice (both air and OVA exposed) had significantly lower lung compliance at baseline compared to all of the other strains and were most different from the NOS1${}^{-/-}$ (Cdyn: $0.017\pm 0.002$ ($n=12$) versus $0.031\pm 0.0008$ ($n=8$) mL/cmH₂O, resp., $P<.0001$) and NOS2${}^{-/-}$ (Cdyn: $0.017\pm 0.002$ versus $0.029\pm 0.0008$ ($n=24$) mL/cmH₂O, resp., $P=.0002$).

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