NO metabolite levels and Pao₂ in control and eNOS-deficient mice. (A) Steady-state plasma nitrate/nitrite levels in control, SCD, and eNOS-deficient mice. Plasma nitrate/nitrite levels were determined using the Nitrate/Nitrite Colorimetric Assay Kit (Cayman Chemical). NS, not significant. (B) Pao₂ levels in control, SCD, and eNOS-deficient mice. Arterial blood was drawn at baseline conditions for blood gas analysis. Values were mean ± SEM obtained from 3 to 4 mice in each group. P values are shown at the top of the figure.