Nitric oxide (NO) plays an important role in neurotransmission, vascular regulation, immune responses and apoptosis. Since most of the NO is oxidized to nitrite (NO2-) and nitrate (NO3-), the concentrations of these anions have been used as a quantitative measure of NO production. N2577-01 provides an accurate and convenient measurement of total nitrate/nitrite concentration in a simple two-step process. The first step is to convert nitrate to nitrite utilizing nitrate reductase. The second step involves addition of the Griess Reagents which convent nitrite into a deep purple azo compound. Measurement of the absorbance of the azo chromophore accurately determines the total nitric oxide production. Sample Matrix: Cell and Tissue lysates, culture media, urine, plasma and serum, as well as many other biological fluids Detection Limit: The detection limit of the assay is 0.1nmole/well, or ~1uM. Kit Components: N2577-01A: Assay Buffer, 1x30ml N2577-01B: Enzyme Co-factors, 1vial N2577-01C: N