Figure 3: Correlation of EBC nitrate with other pathway targeted metabolites. EBC nitrate showed a positive association with EBC nitrite levels (A) but not with plasma nitrate levels (B) or precursor arginine levels in the EBC samples (C). Interestingly, EBC nitrite concentrations were inversely associated with plasma nitrite levels (D). EBC arginine levels did not show any association with plasma arginine concentrations (E). All statistical correlations were performed with logarithmically transformed values. r represents the Pearson correlation coefficient.