[Screening as a method for determining the serum level of nitric oxide metabolites].

The paper describes a modified method for determining stable nitric oxide (NO) metabolites, which permits one-stage assay of total nitrates and nitrites after blood serum deproteinization. The assay is based on the simultaneous reduction of nitrates and nitrites by vanadium chloride and by diazotization with subsequent stimulation of tinting whose rate is spectrophotometrically estimated at 540 nm. Assay of 100 microl of the deproteinized serum is made, by using a flat-bottomed 96-well plate. The sensitivity of the method is 1.7 microM. The concentration of total NO metabolites detected by the assay in the sera of volunteers ranged from 37.2 to 87.2 microM. It is suggested that the above modified assay may be used in clinical practice for the measurement of the concentrations of terminal NO metabolites since they are early markers of vascular endothelial NO-forming dysfunction.