[Effect of inorganic salts on free radicals production by near UV irradiation of frozen aqueous solutions of adenine and its derivatives].

The addition of Na and Ca chlorides to adenine (A), adenosine (Ado) and adenosine diphosphate solutions at pH 5.3 has been shown to result in intensification of EPR signals in samples irradiated by near UV at 77 K and appearance of signals of Cl2-* and peroxyl radicals. The peroxyl radicals contribution can exceed 30% of total amount of paramagnetic products.

[Influence of inorganic phosphate on the production of free radicals in UV-irradiated frozen tyrosine solutions].

The role of inorganic phosphate as a catalyzer of the production of tyrosyl radical in frozen tyrosine solutions irradiated with near UV light at 77K has been demonstrated by the EPR method. It was shown that the increase in the yield of tyrosyl radicals at pH < 7 correlates with the production of H* atoms and can be explained by the fact that phosphate acts as an acceptor of photoejected electrons. At pH > 7, the increase in the yield of tyrosyl radicals is accompanied by the production of phosphate radicals and OH* and is caused, presumably, by the catalysis of the formation of triplet states of tyrosine molecules by the HPO4(2-) form of phosphate, the fact shown by a number of authors.

[Effect of irradiation intensity on the production of free radicals by near-UV photosensitization of frozen adenine solutions with an inorganic phosphate].

The effect of light intensity on the production of free radicals by near-UV photosensitization at 77 K of frozen aqueous solutions of adenine in the presence of inorganic phosphate has been studied. A quantitative estimation of relative concentrations of the products: hydrogen atoms (H*), adenine, phosphate and OH* radicals was carried out using the computer analysis of EPR spectra of irradiated samples. It was found that the formation of phosphate and OH* radicals in a photosystem results predominantly from the absorption of two photons in the band of illumination.

[EPR study of the influence of hypoxia on nitric oxide formation in the blood of Krushinskii-Molodkina rats].

The influence of hypoxia on nitric oxide formation in the blood of Krushinskii-Molodkina rats has been studied by electron paramagnetic resonance. It was found that nitric oxide synthesis in Krushinskii-Molodkina rats is increased compared with that in Wistar rats. A significant enhancement of the EPR signal of Hb-NO complexes in the animal blood was observed after hypoxia simulating the altitude of 5000 m above the sea level, in particular in the presence of sodium nitrite and the NO-synthase inhibitor L-nitroarginine.

[Analysis of free-radical products of near-UV irradiation at 77 K of frozen adenine and adenosine diphosphate solutions containing inorganic phosphate].

Irradiation by near-UV light at 77 K of aqueous solutions of inorganic phosphate in weakly acidic conditions in the presence of the photosensitizers adenine and adenosine diphosphate results in the formation of free radicals of these compounds, photosensitized free radicals of phosphate itself, and H* and OH* radicals. The relative concentrations of free radical products were estimated by the analysis of total ESR signals registered in the region of g = 2.00 in the photosystems Ade + Pi and Adphi + Pi using the original computer program of ESR spectra simulation.