[Change in blood viscosity and hematocrit during cooling of an animal].

When studying temperature dependencies of rat's blood viscosity, cooled in vivo and in vitro, we have identified the differences in their nature. An attempt is made to evaluate contribution of hematocrit into a rise in the viscosity of rats being cooled.

[Properties of the adenylate cyclase system of isolated hepatocytes following freezing-thawing].

The effect of various regimen of freezing and thawing on the functional state of one of the most important receptor-regulatory cell systems, i. e. adenylate cyclase complex (ATP-pyrophosphate lyase cyclating E C 4.

[Effect of freezing-thawing on the adenylate cyclase activity of the rat liver].

Various regimes of freezing and thawing as well as adrenaline and fluoride ions are studied for their effect on the adenylate cyclase activity in liver tissue preparations. The reduction of basal and fluoride-stimulating adenylate cyclase activity and a decrease in the adrenaline-stimulating activity of the enzyme after freezing and thawing are shown. Freezing and thawing are studied for molecular mechanisms of their damaging effect on adenylate cyclase.

[Effect of the permeability of lysosomal and mitochondrial membranes on the ability of their cryoextracts to inhibit the protein-synthesizing activity of cell-free systems].

Changes in permeability of lysosomal and mitochondrial membranes were studied under different temperatures at which cryoextracts from organelles inhibit most distinctly the protein synthesizing activity of the cell-free system from the rat liver. It is found that mitochondria are more sensitive to the effect of low temperature effect than lysosomes. Overcooling of the mitochondria suspension to the temperature of the free water crystallization is shown to cause no release of the protein synthesis inhibitor.

[Study of the state of mitochondria at low temperatures by the ESR method].

Possible usage of ESR probe method for studying low temperature effect on structural and functional state of mitochondria is under study. It is shown that during freezing out of mitochondrial water there is sharp dehydration of intermitochondrial matrix and membrane thickening. The facts are given about damage of barrier function of the membrane at the moment of appearance of extramitochondrial liquid phase during thawing.

[Effect of freezing-thawing on the activity of lactate dehydrogenase isoenzymes].

The activity of isolated M4- and H4-lactate dehydrogenase isoenzymes is studied after freezing in the saline solution to -8, -9.5, -23 and -30 degrees C. It is shown that the activity of H4-lactate dehydrogenase does not change, M4-lactate dehydrogenase being partially inactivated.

[Role of lysosome permeability disorders in the mechanism of the low-temperature inhibition of protein biosynthesis in the rat liver].

The effect of the supernatants of lysosomes subjected to a rapid or slow freezing and thawing on the protein-synthesizing activity of the rat liver postmitochondrial supernatant (S15) has been studied. It has been found that the addition of supernatants obtained after a slow freezing or thawing to a cell-free system results in a significant inhibition of 14C-leucine incorporation that is in a good agreement with their RNase activity. However, the RNase activity of lysosomal supernatants or Triton-lysate appears to be higher that the inhibitory effect on protein biosynthesis.

[Changes in Na+, K+-ATPase and acetylcholinesterase activity in red cell membranes after freezing-thawing].

The activity of Na+, K+ATPase (EC 3.6.1.

[Cytoplasmic enzyme release into the extracellular medium during the freezing and thawing of leukocytes].

The activity of cytoplasmic enzymes (hexokinase, phosphorylase, glucose-6-phosphate dehydrogenase, lactate dehydrogenase) in the extracellular medium following leucocyte freezing-thawing to -30, -70, -140 or -196 degrees C was studied. The appearance of these enzymes in the freezing medium has been found to be associated with the disruption of cellular elements. The source of lactate dehydrogenase activity in the extracellular medium was shown to be due not only to disrupted leucocytes, but also to cells remained after freezing-thawing.

[Effect of steroid hormones on the stability of isolated lysosomes during freezing].

Effect of hydrocortisone and dexamethasone, combined with cryoprotector polyethylene oxide, on stability of lysosomal membranes was studied after freezing of the lysosomes using various conditions. In freezing of the lysosomal suspension together with the cryoprotector and the steroid hormones numerous enzymes were liberated from the organelles less distinctly as compared with the control experiments without hormones. The steroid hormones stabilized apparently the phospholipid membrane of lysosomes under conditions of freezing.

[Effect of cryoprotectors on stability of lysosomes under cooling].

The efficiency of cryoprotectors-polyethylene oxide 400, glycerol, oxyethylated glycerol, dimethyl sulphoxide was studied relative to stabilization isolated lysosomes under different regimes of freezing-thawing. It is established that a decrease in the amount of lysosome hydrolases (RNase, DNase, catepsin D, phosphatase) released to the environment is the most significant in the presence of the mentioned substances uncer slow freezing-thawing.

[Changes in subunit composition of lactate dehydrogenase at low temperatures].

Hybridization of M4- and H4-isoenzymes of lactate dehydrogenase in saline medium was studied during slow freezing down to -9.5; -23 and -30 degrees C. It is established that appearances of the enzyme hybrid forms is associated with free water freezing out and with an increase in the concentration of salts in the solution.

[Effect of freezing-thawing on proteolytic activity of soluble and immobilized trypsin].

The proteolytic activity of soluble trypsin was studied after the effect of different freezing-thawing conditions ranging from 0 to 196 degrees C. The enzyme is inactivated most essentially during a slow warming of the preparations under experiment. The trypsin activity decrease is found to depend directly on the number of the freezing-thawing cycles.

[Effect of deep freezing on isolated rat liver lysosomes].

The level of the non--sedimentating activity of acid hydrolases (deoxyribonuclease, phosphatase, cathepsins) and electron microscopy of lysosomes has been studied after freezing to --30 degrees, --70 degrees, --140 degrees and --196 degrees. It has been found that enzyme solubilistion and lysosome ultrastructure distortion are mostly marked in the temperature range between 0 degrees and --30 degrees C. Additional membrane damage is observed in the temperature range from --140 degrees to --196 degrees C.