Nitrogen-13--Labeled Nitrite and Nitrate: Distribution and Metabolism after Intratracheal Administration

• Published in: Science (American Association for the Advancement of Science) 1981-04, Vol.212 (4490), p.58-61
• Main Authors: Parks, Norris J., Krohn, Kenneth A., Mathis, Chester A., Chasko, Joseph H., Geiger, Kenneth R., Gregor, Marsha E., Peek, Neal F.
• Format: Article
• Language: English
• Subjects: Animals; Anions; Blood; Blood plasma; Chromatography, High Pressure Liquid; Injections, Intravenous; Intravenous injections; Lungs; Mice; Mice, Inbred BALB C; Nitrates - administration & dosage; Nitrates - metabolism; Nitrites; Nitrites - administration & dosage; Nitrites - metabolism; Nitrogen Isotopes; Oxidation; Oxidation-Reduction; Rabbits; Species Specificity; Tissue Distribution; Trachea
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.7209517

Radioactive nitrogen-13 from nitrite (NO$_{2}{}^{-}$) or nitrate (NO$_{3}{}^{-}$) administered intratracheally or intravenously without added carrier to mice or rabbits was distributed evenly throughout most organs and tissues regardless of the entry route or the anion administered. Nitrogen-13 from both anions was distributed uniformly between plasma and blood cells. We found rapid in vivo oxidation of NO$_{2}{}^{-}$ to NO$_{3}{}^{-}$ at concentrations of 2 to 3 nanomoles per liter in blood. Over 50 percent oxidation within 10 minutes accounted for the similar nitrogen-13 distributions from both parent ions. The oxidation rates were animal species--dependent. No reduction of $^{13}$NO$_{3}{}^{-}$ to $^{13}$NO$_{2}{}^{-}$ was observed. A mechanistic hypothesis invoking oxidation of $^{13}$NO$_{2}{}^{-}$ by a catalase--hydrogen peroxide complex accounts for the results. These results imply a concentration dependence for the in vivo fate of NO$_{2}{}^{-}$ or nitrogen dioxide.