[Effect of thyroxine on the lactate dehydrogenase isoenzyme composition of chicken tissues in ontogeny]. / Vliianie tiroksina na izofermentnyi sostav laktatdegidrogenazy v tkaniakh kur v ontogeneze.

Using disc electrophoresis in polyacrylamide gel, studies have been made on the content of isoenzymes of lactate dehydrogenase in the mitochondria and cytoplasm from the brain, heart and liver after thyroxine administration to embryonal, early postnatal and adult hens. After this administration, the isoenzymic composition becomes more complex, redistribution of separate isozymes being observed in ontogenesis. The level of aerobic form of LDH increases at early stages of ontogenesis, that of anaerobic ones--in adult birds. Basing on their different functional role due to the presence of H- and M-subunits, it may be suggested that thyroxine administration results in a compensatory increase of the oxidative or glycolytic processes at the corresponding stages of ontogenesis, these changes reflecting phylogenetic peculiarities of the formation of the hormonal control of lactate dehydrogenase in tissues of birds.

[Effect of cations and DNP on ATPase activity in different tissue fractions of birds' brains]. / Vliianie kationov i DNF na ATF-aznuiu aktivnost' v razlichnykh fraktsiiakh tkani mozga ptits.

ATP-ase activity and the effect of cations (Na+, K+, Mg2+, Ca2+) and DNP on its activity have been studied in avian brain homogenates and mitochondrial and supernatant fractions (microsomes + hyaloplasma). Highest levels of Na+ + K+ -stimulated ATP-ase activity has been shown in avian brain crude mitochondrial fraction, next in supernatant and lowest in homogenates. Following three-fold freezing and thawing, enzyme activity in homogenates and mitochondrial fractions increases considerably and decreases in the supernatant. Highest Mg2+ -stimulated ATP-ase activity is found in avian brain homogenates, next in mitochondrial fractions and supernatants. Mg2+ -stimulated ATP-ase activity is not changed considerably following three-fold freezing and thawing of brain preparations. Highest Ca2+ -stimulated ATP-ase activity has been observed in the supernatant fraction and its activity is considerably reduced following freezing and thawing. Avian brain mitochondrial fractions have high DNP-stimulated ATP-ase activity. Following freezing and thawing of brain preparations DNP-stimulated ATP-ase activity is not changed considerably. The results obtained indicate that in avian brain homogenates and other preparations, cation and DNP-stimulated ATP-ase have different activities. Three-fold freezing and thawing of brain tissue preparations affect these activities differentially.