[Rapid metabolic changes in the blood and organs of rats under the influence of electron pulse radiation at superhigh doses]. / Bystrye metabolicheskie izmeneniia v krovi i organakh krys pod vliianiem impul'snogo izlucheniia élektronov v sverkhvysokikh dozakh.

Early metabolic changes have been studied in the peripheral blood, brain, adrenals, spleen, and liver of rats after irradiation with 500 Gy. Using ESR spectroscopy we showed the formation of a great amount of hemoglobin nitrosyl complexes and methemoglobin in the blood and spleen, thus suggesting that the endothelium-derived relaxing factor, nitric oxide (NO), was released due to irradiation stimulation and sharp hypoxia in brain. Polarographic data concerning the disturbance of brain mitochondrial function (activation of succinate hydrogenase oxidation) allowed a conclusion that hypoxia appeared after irradiation at superlethal doses. Antioxidative activity of lipids in various tissues differed in the rats with "the early loss of performance" syndrome and in normal rats. Possibility of ammonia intoxication of the brain soon after irradiation at superlethal doses has been discussed.

[The effect of ionizing radiation at superhigh dosages on the ATP content in the rat brain]. / Vliianie ioniziriushchego izlucheniia v sverkhvysokikh dozakh na soderzhanie ATF v golovnom mozge.

The ATP content of rat brain was shown to decrease considerably (20-60%) during the first minutes following high-energy electron irradiation with doses of 300 and 500 Gy. A transient nature of changes and a more pronounced decrease in ATP with increasing radiation dose and manifest neurologic disturbances indicate that the energy metabolism is involved in the pathogenesis of early neurologic disturbances in animals.

[The effect of mexamine on liver mitochondrial function in rats in vivo and in vitro from the aspect of the mechanisms of the pharmacological and radioprotective action of the protector]. / Vliianie meksamina na funktsional'noe sostoianie mitokhondrii pecheni krys in vivo i in vitro v aspekte mekhanizmov farmakologicheskogo i radiozashchitnogo deistviia protektora.

The polarographic study of the functional status (FS) of rat liver mitochondria subjected to the effect of mexamine in vivo and in vitro and the hypoxic hypoxia in vivo has revealed various FS changes displaying disconnecting and rotenone-like effects and posthypoxic activation. With a mexamine dose of 50 mg/kg in vivo the direct effect of the protector contributes considerably to the mitochondrial FS. Within a wide range of mexamine doses no relationship was found between the pattern of the mitochondrial FS change in the liver and the protective effect with respect to bone marrow.

[Evaluation of the radioprotective action of mexamine based on the cellularity index of the rat thymus]. / Otsenka radiozashchitnogo deistviia meksamina po pokazateliu kletochnosti timusa krys.

Tie administration of mexamine leads to emigration of thymus cells levelling the radioprotective effect of the compound as determined by total cellularity of the organ. Processes of thymus cell depletion were additive after the effect of mexamine and ionizing radiation. It was found possible to estimate the radioprotective efficiency of mexamine with regard to thymus tissue cellularity diminution after the administration of the preparation.

Using 2'(3')-O-trinitrophenyl derivatives of adenine nucleotides to study the structure and mechanism of functioning of soluble mitochondrial ATPase.

The 2'(3')-O-trinitrophenyl (N3ph) derivatives of the adenine nucleotides are strong competitive inhibitors of isolated mitochondrial ATPase (factor F1). Ki decreases in the order N3phAdo greater than N3phAdo greater than N3phAMP greater than N3phADP and is equal to 8 nM for N3phADP. Picric acid, which activates the ATPase reaction of factor F1 without changing the Km(app), prevents the inhibiting action of N3phADP. At pH 7.6 the inhibiton of factor F1 is accompanied by the binding of one molecule of N3phADP to a molecule of the enzyme. This binding leads to changes in the absorption spectrum, but not in the intensity of the fluorescence of the N3phADP. At pH 6.7 one or two molecules of N3phADP bind with the tight binding sites of factor F1. This binding is accompanied by the manifold enhancement of the fluorescence of N3phADP. The results obtained indicate that the sites of factor F1 that tightly bind nucleotides are immersed in the hydrophobic pocket of the protein molecule.