Metabolism of Nitric Oxide and Nitrite, Nitrate

Abstract

Metabolic fate of inhaled NO was studied by exposure to ¹⁵NO and intraperitoneal in jection of ¹⁵N-nitrite and ¹⁵N-nitrate using rats and mice.
1) After exposure to ¹⁵NO (145 ppm, 123 min) and intraperitoneal in jection of ¹⁵N-nitrite (2 mg as ¹⁵N/animal) and ¹⁵N-nitrate (2 mg as ¹⁵N/animal), the recoveries of ¹⁵N in rat urine of 48 hours period were estimated. These values were 55, 53 and 78% of ¹⁵N exposed or in jected respectively.
2) The ¹⁵N-nitrite-ion in the urine was converted into the 6-nitro-derivative of 3, 4-xylenol, and was identified, determined by GC-MS method. The ¹⁵N-urea in the urine was identified and determined by using urease. The composition of ¹⁵N in rat urine after exposure to ¹⁵NO was 75 and 24% in the form of NO₃^- and urea respectively. At the case of rat urine, after in jection of ¹⁵N-nitrite, the unknown ¹⁵N compound was found in the considerable content, although it was not found in the case of inhalation. The amount of urea-¹⁵N after in jection of ¹⁵N-nitrate was lower than these of ¹⁵N-nitrite in jection.
3) Distribution of ¹⁵N was estimated after intraperitoneal in jection of ¹⁵N-nitrite (0.62 mg as ¹⁵N/mouce) using mice, and 60.7, 7.8, 0.3 and 1.6% of ¹⁵N in jected were found in the urine, fecal, exhaled gas during 48 hours, and the whole body after 48 hours, respectively. The ¹⁵N of remaining 30% was not recovered.