[Activity of alanine- and aspartate-aminotransferases in organs of albino rats subjected to whole body gamma-irradiation and physical exercise]. / Issledovanie aktivnosti alanin- i aspartataminotransferaz v organakh belykh krys pri total'nom gamma-obluchenii i fizicheskoi nagruzke.

The investigations of enzyme activity such as aspartate aminotransferase (AST, KE 2.6.1.1.) and alanine aminotransferase (ALT, KE 2.6.1.2) playing an important role in proteins metabolism were carried out in cell fraction of rat liver, myocardial and skeleton muscle after the influence of ionizing radiation (6 Gy) and the maximum physical loading. It was shown that physical loading furthered the increase of ALT-activity in all cell fractions except liver cytosol. And it was noted a strongly pronounced tendency of AST-activity to lowering, except muscle cell fractions. ALT-activity level in irradiated animals showed phase changes dependent on the term of observation and the kind of investigated tissues. The primary lowering of AST-activity in cell fractions of the investigated tissues is a conformity to natural laws of the gamma-irradiation influence on AST in most cases. It was shown that the physical tiredness made worse penetrated radiation action on the investigated enzymes.

[Effect of repeated injections of GABA on the GABA shunt and various associated reactions in the rat brain]. / Vliianie mnogokratnykh in''ektsii GAMK na GAMK-shunt i nekotorye sviazannye s nim reaktsii v golovnom mozge krys.

Effect of repeated administrations of gamma-amino butyric acid (GABA) at doses corresponding to those which are used in clinical medicine, on the state of GABA-shunt and intensity of alpha-ketoglutarate dehydrogenase and aminotransferase reactions as well as on the level of GABA and glutamate was studied in cerebellum, cortex and trunkus cerebri of rat brain. Administration of GABA (5 injections at a dose of 5 mg/kg) caused distinct alterations in central nervous system, which involved activation of GABA-transaminase, utilizing GABA, and inactivation of glutamate decarboxylase, producing the amine, as well as a decrease of GABA and glutamate levels and an increase in alpha-ketoglutarate utilization and activation of aminotransferase reactions. These alterations were especially distinct in cerebellum, where initial high intensity of GABA shunt functioning and minimal level of GABA were observed. The alterations observed suggest the existence of pronounced stimulating effect of GABA, even at low doses, on reactions of energy metabolism in brain.

[The use of pyridoxal-5-phosphate in determining aminotransferase activity in brain tissue]. / Ob ispol'zovanii piridoksal'-5-fosfata pri opredelenii aminotransferaznoi aktivnosti v tkani golovnogo mozga.

When aspartate- and alanine transaminase (AST and ALT, respectively) activities were studied in homogenates of rat cerebellum, brain cortex and brain stem (using a modified procedure by Raitman and Frenkel), addition of 50 microM pyridoxal-5-phosphate (PALP) increased 2-3-fold the activity studied. With an increase in PALP concentration from 6.25 microM up to 200 microM AST- and ALT-activities increased dose-dependently, while at 100-200 microM concentration of PALP saturation of the reaction occurred and 200 microM of PALP decreased the AST activity. 10 min preincubation of these homogenates without and in presence of 0.25 mM PALP led to a distinct increase in amount of ketoderivatives reacting positively with 2,4-dinitrophenyl hydrazine, most markedly elevated in the sample containing PALP. At the same time, prolongation of the preincubation period under standard conditions in presence of an excess of the substrates and 50 microM PALP did not cause any increase in AST- and ALT-activities. During studies of the transaminase activity in brain biopsy, in the material obtained after neurosurgical operations as well as in medico-biological experiments, the activity should be estimated using two sets of conditions: under standard conditions and in presence of 50-100 microM PALP but without preincubation with PALP.

[Early changes in GABA and glutamate levels and aminotransferase activity in parts of the rat brain following whole-body gamma irradiation at an absolutely lethal dose]. / Rannie izmeneniia urovnia GAMK, glutamata i aminotransferaznoi aktivnosti v otdelakh golovnogo mozga krys posle obshchego gamma-oblucheniia v absoliutno letal'noi doze.

The contents of gamma-aminobutyric acid (GABA) and glutamate (GL) as well as GABA-aspartate- and alanine aminotransferase activities were measured in rat cerebellum, cerebral cortex and truncus cerebri 1, 3, 6, 24 and 48 hr following total-body gamma-irradiation (60Co) with a dose of 30 Gy. All the indices under study changed in a similar way in the cortex and truncus cerebri while in the cerebellum, GABA level increased and GABA-alpha-ketoglutarate aminotransfearse activity decreased 60 min after irradiation. The levels of GABA and GL in the cortex and truncus cerebri decreased immediately and increased 24 hr after irradiation. Activity of aminotransferases changed in a phase manner: changes in aspartate- and alanine aminotransferase activity were more pronounced than those of GABA-alpha-ketoglutarate aminotransferase activity and correlated with the glutamate level changes.

[Change in the ornithine carbamoyltransferase activity in rats following roentgen irradiation and administration of a vitamin-coenzyme complex]. / Izmenenie aktivnosti ornitinkarbamoiltransferazy u krys posle rentgenovskogo oblucheniia i vvedeniia vitaminokofermentnogo kompleksa.

A whole-body X-irradiation (5.82 Gy) increases the activity of ornithine carbamoyl transferase (OCT) on days 3, 7, 15 and 60. After the administration of a complex of vitamins and coenzymes on days 7, 15 and 60 OCT activity decreased as compared to that of untreated animals. A correlation was noted between the activity of OCT in the liver and blood serum.