The oxidation-reduction equilibrium shifting after the introduction of natrium nitrate (NN) has a duration related effect. A single NN introduction in a toxic dosage decreases the force of the blood's thioldisulfide and ascorbate systems (AOS). On the contrary, processes in the liver of laboratory animals are marked by a tendency towards growing AOS activity due to an increase in the reduced forms of thiol enzymes and ascorbic acid content. The process of subtoxic dosage action of natrium nitrate is characterized by decreased volume of the enzyme deoxidation thioldisulfide system of the liver.