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Conversion of inhaled nitric oxide to nitrate in man
Author(s) -
Westfelt Ulla Nathorst,
Benthin Günther,
Lundin Stefan,
Stenqvist Ola,
Wennmalm Åke
Publication year - 1995
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1995.tb14948.x
Subject(s) - inhalation , nitric oxide , urine , chemistry , excretion , nitrate , urinary system , pharmacology , in vivo , vasodilation , anesthesia , endocrinology , medicine , biochemistry , biology , microbiology and biotechnology , organic chemistry
1 Nitric oxide (NO) is potentially useful as a selective vasodilator drug in infants and adults with pulmonary hypertension. In vitro and in vivo observations demonstrate that NO may be converted to nitrate in the blood, to be further excreted into the urine. The aim of the present study was to assess quantitatively the importance of this pathway for inhaled NO in human subjects. 2 Healthy subjects inhaled 15 NO (25 p.p.m.) for 1 h. The plasma and urine levels of 15 NO 3 ‐ were followed for 2 and 48 h, respectively. 3 The measured retention of 15 NO in the lungs was 224 ± 13 μmol, corresponding to 90 ± 2% of the inhaled amount. Plasma 15 NO 3 ‐ increased during the inhalation of 15 NO, to about 15μmoll _1 , and fell when inhalation of 15 NO was terminated. 4 Urinary excretion of 15 NO 3 ‐ during the first 24 h after inhalation was 154 ± 12μmol. During the following 24 h another 8 ± 2 μmol of 15 NO 3 appeared in the urine. 5 We conclude that conversion of inhaled NO to nitrate is a major metabolic pathway in man, covering more than 70% of its inactivation. The metabolic fate of the remaining NO inhaled requires further study.