Evidence by gas chromatography-mass spectrometry of ex vivo nitrite and nitrate formation from air nitrogen oxides in human plasma, serum, and urine samples.
Nitrite and nitrate in body fluids and tissues result from dietary source, endogenous nitric oxide (NO) production and from NO and its higher oxides (NO(x)) present as pollutants in the atmosphere. Nitrite and nitrate in human blood serum and plasma or urine are commonly used as biomarkers and measures of endogenous NO synthesis. In addition to dietary intake of nitrite and nitrate, our study indicates that NO(x) naturally present in the laboratory air may be an abundant source for nitrite and nitrate in human serum, plasma, and urine ex vivo. These artifacts can be effectively reduced by closing sample-containing vials during sample treatment.
Institute of Clinical Pharmacology, Hannover Medical School, 30625 Hannover, Germany. tsikas.dimitros@mh-hannover.de
Dimitrios
D
Tsikas
Anja
A
Mitschke
Frank-Mathias
FM
Gutzki
Stefan
S
Engeli
Jens
J
Jordan
D000388:Air; D001774:Blood Chemical Analysis; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D009566:Nitrates / Q000032:analysis* / Q000097:blood / Q000652:urine; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000032:analysis* / Q000097:blood / Q000652:urine; D013997:Time Factors
D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide