Recent data concerning physiological and pathological characteristics of nitric oxide were reviewed, as well as necessity of evaluation in vivo of NO-producing activity was discussed. A modification of method for the end stable NO metabolites (nitrites and nitrates, NOX) determination in human body fluids, including blood serum, was reported. After deproteinization of serum with ethanol, the one step assay was possible. The principle of the assay is simultaneous reduction of nitrate to nitrite with the use of vanadium (III) chloride followed by Griess reaction and the absorbance measurement at 540 nm.
The NOx quantification was carried out in microtiter plate, 100µl of sample was enough for determination. The sensitivity of the assay is 1,7 µM, the coefficient of variation for this method were 6,2% and 10,9% for inter- and intra-assays, respectively. The NOx concentrations measured by this procedure ranged from 37,2 to 87,2µM. In conclusion, this rapid, simple, nonexpensive, reliable and sensitive method allows to evaluate serum nitrites and nitrates concentration as a measure of NO production both in normal and pathology.
