Nitric Oxide (NO) is produced in trace quantities by neurons, endothelial cells, platelets, and neutrophils in response to homeostatic stimuli. This NO is scavenged rapidly (t½ = 4 s) and acts in a paracrine fashion to transduce cellular signals. NO interacts with the HEME prosthetic group of guanylate cyclase, activating the enzyme and leading to increased cGMP levels. Other cells (macrophages, fibroblasts, and hepatocytes) also produce NO in micromolar concentrations in response to inflammatory or mitogenic stimuli. These very high levels of NO lead to the formation of peroxynitrite, destruction of iron-sulphur clusters, thiol nitrosation, and nitration of protein tyrosine residues. Thus, the amount of NO produced in different biological systems can vary over several orders of magnitude and its subsequent chemical reactivity is diverse. The final products of NO in vivo are nitrite (NO2-) and nitrate (NO3-). Relative proportions of NO2- and NO3- within a sample are variable and cannot be predicted with certainty. Therefore, the best index of total NO production is the sum of both of these products. Cayman Chemical’s Nitrate/Nitrite Fluorometric Assay Kit provides a convenient method for the quantitation of low levels of NO2- and NO3- in biological samples (particularly tissue culture medium). Previously undetectable concentrations of nitrate/nitrite in a variety of samples can be accurately quantitated using this kit as it extends the lower limit of detection by 20-fold over our popular colorimetric version. The minimum detectable quantity of NO2/NO3 is ~50 nM.Needed but not supplied: Please download the kit booklet to verify if UltraPure Water (Milli-Q or equivalent) or any other components are needed for this assay.WARNING This product is not for human or veterinary use.
