[The nitric oxide cycle in mammals and nitrite reducing activity of heme-containing proteins].

A nitric oxide cycle is proposed, which explains numerous experimental data demonstrating that under hypoxic conditions synthesis of NO was elevated. Two pathways appear to be fundamental for activation of NO formation: 1) activation of L-arginine utilization as its content was decreased in blood; 2) transfer of heme-containing proteins hemoglobin, myoglobin, cytochrome oxidase and cytochrome P-450 into their deoxy-form, where these proteins are able to reduce NO2- into NO. This suggests that the nitric oxide cycle may be considered as a compensatory mechanism which allowed the various cells to acquire reduced dependence on overloading under conditions of oxygen and energy deficiency.

[Do nitrite ions participate in regulating systems of intra- and intercellular signalling?].

Effect of nitrite ions on content of proteins (hemoglobin, albumin and others), peptides (AKTH and endothelin-1, 2) of total alpha-aminonitrogen and cGMP was studied in rat blood. The data obtained suggest that NO2- may be involved in regulation of these physiologically active substances because NO2- are the deposited form of nitric oxide which may regulate the inter- and intracellular signal systems.

[The compensatory-adaptive mechanisms in nitrite-induced hypoxia in rats].

Concentration of blood proteins, alpha-amino nitrogen, cGMP and endothelin-1,2 was studied in rat's blood at nitric hypoxia. The injection of NaNO2 (5 mg/100 g body weight) was followed by decrease in total protein, albumin and hemoglobin content and by sharp increase in methemoglobin and Hb-NO complexes concentration in rat's blood. Simultaneously, the elevation of free amino acids and peptides with m.