[Effects of hypothermia on ATPase activity in the cerebral tissue of rats]. / Vliianie gipotermii na ATF-aznuiu aktivnost' mozgovoi tkani krys.

The hypothermia 20 degrees C of various periods of action stimulates greatly the activity of Na,K-ATF-ase and causes some insignificant changes in the process of Mg-ATF-ase in homogenates, synaptosomal and mitochondrial fractions, extracted from cortex of big hemispheres. The gained data testifies to some differences of the properties of membrane while cooling.

[Effect of extracellular ATP on the characteristics of synaptosomes from the rat cerebral cortex]. / Vliianie vnekletochnogo ATF na nekotorye kharakteristiki sinaptosom iz kory golovnogo mozga krysy.

The extracellular ATP, Ca2+, Mg2+, ATP-Ca2+ and ATP + Mg2+ affect the optical density (at 520 nm) and turbidity spectra in suspensions of light and heavy synaptosomes and in mitochondria prepared from rat cerebral cortex. The properties of the light synaptosomes are associated only with their volume changes; the heavy synaptosomes and mitochondria also change their refractive indices. These results could be interpreted by structural (conformational) rearrangements occurring in membranes under such conditions. A support for this assumption was found in the studies on the spin-labeled synaptosomes.

[Osmotic properties of heavy and light synaptosomes of the rat cerebral cortex]. / Osmoticheskie svoistva tiazhelykh i legkikh sinaptosom kory golovnogo mozga krysy.

A comparison has been carried out of osmotic properties of light and heavy synaptosomal fractions and a mitochondrial fraction from the rat brain cortex. A critical change is the rate of swelling at a definite time, allowing to subdivide the process into two phases, was shown. Throughout the swelling, its rate for heavy synaptosomes and mitochondria was much higher than that for the light ones. According to the initial rate of swelling in isoosmotic glycerol, the fractions examined can be arranged in the following order: mitochondria < light synaptosomes < heavy synaptosomes. Both total, light and heavy synaptosomes reveal the properties of ideal osmometers. The osmotic properties of synaptosomes and mitochondria are largely dependent on pH of the medium: with a shift towards acidic values of pH the swelling rate decreases to increase at more alkaline values. Especially well-pronounced changes occur at pH 6.8 and pH 7.3.

[Kinetics of deoxyribonuclease I action on the DNA of different white rat tissues]. / Kinetika deistviia dezoksiribonukleazy I na DNK iader razlichnykh tkanei beloi krysy.

Studies have been made on the kinetics of the effect of DNAse I on nuclear DNA from the brain cortex, liver, spleen and kidney of albino rats. In all the nuclei studied, two DNA sites revealed which especially differ in the rate of their splitting. The share of rapidly splitted DNA amounts in the nuclei of the kidney and brain cortex up to 30%, in those of the liver and spleen -- about 25%. These findings are discussed in relation to the data available on the share of transcribed chromatin in the same tissues obtained by hybridization with nuclear RNA. For the brain and liver this method yields the same values, whereas for the spleen and kidney this test yields significantly lower values, i. e. about 10%.