Figure 4

Relative enrichment of ¹⁵N-nitrite in tissues after dietary intervention analyzed by LC–MS/MS. (A) ¹⁵N-labeled nitrite content was measured by LC–MS/MS. Nitrite derivatization by DAN was performed to yield NAT. The result was based on the percentage ratio of ¹⁵NAT/(¹⁴NAT + ¹⁵NAT). Data are plotted as average ± standard deviation (n = 4–6, * p < 0.05). (B) The proportion of ¹⁵N-labeled nitrite in control and 3-day Na¹⁵NO₃ supplementation group is shown.