It is well known that NO has significant physiological effects including regulation of smooth muscle tonus, tissues differentiation, resistance to stress, inhibition of platelet aggregation and some gene expression. However, the practical application of scientific research on NO production and its metabolism is still mainly lacking. This can be explained by the insufficient knowledge of NO metabolism in physiological and pathological processes. The difficulty of quantitative determination of NO metabolites in biological objects is the main reason that limits the possibility of such studies. Modern methods are not able to determine the composition and concentration of these compounds in biological objects quickly and correctly. Application of enzymes to evaluate the NO metabolites is very promising due to their high specificity in physiological conditions.
This review analyzes the various methods of nitro- and nitroso-compounds determination in biological objects. It is shown that methods enzyme-based assays are suitable for the correct, fast, cheap and high sensitive estimation of basic NO metabolites in biological objects. This makes possible to establish the NO metabolite content in biological objects, and particularly, the content of physiological NO donors and its variations in physiological and pathological processes. This data can be used for diagnostic in medicine and agriculture and also for testing of NO donors.