Hypoxia is one of the most common states of the body. Virtually any extreme conditions of the body and any pathological process are directly or indirectly related to disturbed oxygen supply to the body. Hypoxia and associated metabolic disorders are the key pathogenetic factors of all severe complications in extreme conditions of various origins [1,2]. Studies of metabolic changes in the body showed that hypoxia is characterized by the prevalence of glycolysis rather than aerobic metabolism, a rapid depletion of reserves of glucose, glycogen, ATP, and creatine phosphate and an increase in the content of lactate [1][2][3][4]. As a result of these changes, metabolism is shifted toward catab olism, which is characterized by activation of proteol ysis, free radical processes, and lipid peroxidation [4,5]. There are no metabolic processes that would not change during hypoxia. In recent years, in connection with the discovery of the major role of nitric oxide as a factor involved in relaxation of blood vessels and a uni versal regulator of many biochemical processes in the body, it is of interest to study changes in the content of nitric oxide in blood and organs of animals under low oxygen conditions. Earlier, we studied the influence of hypoxia on the content of nitric oxide in the blood of KrushinskyMolodkina rats [6,7]. It was shown that the synthesis of NO in the blood of rats of this strain is increased as compared to Wistar rats. There is evidence indicating that hypoxia induced by placing Krushinsky-Molod kina rats to an altitude of 5000 m is accompanied by an increase in the intensity of the EPR signal of Hb NO complexes in blood. Despite the large number of stud ies on the formation of nitric oxide in the body, the question about the nature of all sources of increased nitric oxide in hypoxic conditions remains unan swered.We have investigated changes in the relative content of nitric oxide in the heart tissues of animals in hypobaric hypoxia (at the initial stages, immediately after the cessation of hypoxia) both separately and in the presence of sodium nitrite, an additional source of nitric oxide, and nitroarginine (L NNA), an inhibitor of nitric oxide synthesis by NO synthases. MATERIALS AND METHODSIn this study we used male Krushinsky-Molodkina rats 5-6 months old weighing 280-320 g. We per formed seven series of experiments (six animals in each experiment): 1-control (animals were intrap eritoneally injected with saline); 2-experiment with placing animals that were intraperitoneally injected with saline to an altitude of 5000 m (pressure chamber hypoxia); 3-experiment with the injection of L NNA in saline; 4-experiment with the injection of L NNA in saline + hypoxia; 5-experiment with the injection of NaNO 2 in saline; 6-experiment with the injection of NaNO 2 in saline + hypoxia; and 7-experiment with combined injection of NaNO 2 + L NNA in saline + hypoxia.Sodium nitrite at a dose of 0.5 mg per 100 g body weight and L NNA at a dose of 2.5 mg per 100 g of body weight were injected intraperitoneally. In ...

Ascorbic acid is involved in the formation of nitrogen oxide in leukocytes of humans and animals. It is an important role of the AA in maintaining the immune status of the organism.