title: Determination of nitrite plus nitrate and malondialdehyde in human plasma: analytical performance and the effect of smoking and exercise.
abstract: The aim of this study was to evaluate the analytical performance and clinical usefulness of spectrophotometric assays for the measurement of the plasma levels of nitrite plus nitrate (NOx), and malondialdehyde (MDA), as an index of nitric oxide release and lipid peroxidation, respectively. We studied 30 healthy sedentary volunteers, 12 endurance athletes and 12 regular heavy smokers. The lower limit of quantification for plasma NOx concentration was 1 micromol/l, and linearity was observed from 1 to 40 micromol/l of NOx concentration. Variation in replicate samples within or between days was always below 5%. NOx levels were significantly higher in athletes compared to both control subjects and smokers (p<0.05 and p<0.001, respectively), as well as in healthy subjects compared to smokers (p<0.05). The analytical limit of quantification for plasma MDA concentration was 0.03 micromol/l, and linearity was observed from 0.03 to 20 micromol/l of MDA concentration. Variation in replicate samples within or between runs was <5%. Mean MDA concentration was significantly higher in smokers compared to control subjects and athletes (p<0.001). A significant inverse relationship (p<0.001) was observed when comparing NOx with MDA (r=-0.49) or LDL levels (r=-0.30) in the total population. The assays evaluated in this study proved to be sensitive, specific and practicable, and therefore suitable for routine application in clinical chemistry laboratories and/or physiopathological studies involving human blood samples.
authors.affiliation: CNR Institute of Clinical Physiology, Pisa, Italy. cristina.vassalle@nsifc.ifc.pi.cnr.it
authors.forename: Cristina
authors.initials: C
authors.lastname: Vassalle
authors.forename: Valter
authors.initials: V
authors.lastname: Lubrano
authors.forename: Antonio
authors.initials: A
authors.lastname: L'Abbate
authors.forename: Aldo
authors.initials: A
authors.lastname: Clerico
mesh_terms: D000328:Adult; D008078:Cholesterol, LDL / Q000097:blood; D015444:Exercise / Q000502:physiology; D005260:Female; D006801:Humans; D015227:Lipid Peroxidation; D008297:Male; D008315:Malondialdehyde / Q000097:blood*; D009566:Nitrates / Q000097:blood*; D009569:Nitric Oxide / Q000378:metabolism; D009573:Nitrites / Q000097:blood*; D018384:Oxidative Stress; D015203:Reproducibility of Results; D012907:Smoking / Q000097:blood; D013057:Spectrum Analysis / Q000379:methods / Q000592:standards
chemical_list: D008078:Cholesterol, LDL; D009566:Nitrates; D009573:Nitrites; D009569:Nitric Oxide; D008315:Malondialdehyde