The L-Arginine: Nitric Oxide Pathway Is the Major Source of Plasma Nitrite in Fasted Humans

15N guanidino-labelled L-arginine was infused into fasted human volunteers giving, at equilibrium, a stable 1:10 ratio of 15N to 14N arginine in the plasma. Separate GC-MS assays were used to compare the degree of enrichment of plasma arginine, nitrite and nitrate and thus define the quantitative re...

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Bibliographic Details
Published in:Biochemical and biophysical research communications 1995-04, Vol.209 (2), p.590-596
Main Authors: Rhodes, P.M., Leone, A.M., Francis, P.L., Struthers, A.D., Moncada, S.
Format: Article
Language:English
Subjects:
Adult
Arginine - metabolism
Fasting
Gas Chromatography-Mass Spectrometry
Humans
Male
Nitric Oxide - metabolism
Nitrites - blood
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Summary:15N guanidino-labelled L-arginine was infused into fasted human volunteers giving, at equilibrium, a stable 1:10 ratio of 15N to 14N arginine in the plasma. Separate GC-MS assays were used to compare the degree of enrichment of plasma arginine, nitrite and nitrate and thus define the quantitative relationship between the L-arginine:nitric oxide (NO) pathway and the formation of these oxides of nitrogen. 15N nitrite enrichments rose to 8.3% (SD 0.5), five hours after the start of the infusion. In contrast, 15N nitrate enrichments apparently rose to only 1.6% (SD 0.4) at this time. This discrepancy could be explained by our finding that the commonly used Tesch GC-MS nitrate assay is subject to considerable interference from non-nitrate sources in plasma. Taking this into account, nitrate enrichments were similar to those observed for plasma nitrite. These results therefore indicate that the measurement of these compounds in plasma is a valid indicator of NO generation in fasted humans.
ISSN:0006-291X
1090-2104
DOI:10.1006/bbrc.1995.1541