Fig 4. Little uptake of nitrate or nitrite from treatments was found in the brain.

The concentration of (A) nitrate or (B) nitrite was measured using targeted LC-MS/MS in control animals or animals treated with (A) unlabeled and ¹⁵N-labeled nitrate, or (B) unlabeled and ¹⁵N-labeled nitrite. (A-B) Zebrafish brains were collected on day 31 and percent enrichment (in boxes), indicates the relative amount of nitrate or nitrite in the brain that was derived from the treatment. Bars represent the mean concentration ± SEM (n = 6).