[Possible use of the growing liver biological set for hepatic recovery after toxic damage (an experimental study)]. / Vozmozhnosti biologicheskoi kombinatsii, poluchennoi iz rastushchei pecheni, dlia ee vosstanovleniia pri toksicheskom povrezhdenii (éksperimental'noe issledovanie).

The lack of acceptable pharmacological approaches for restoration of the injured liver is associated with complex of mechanisms involved in hepatic regeneration and with difficulty of the target selection. The aim of this research was to study the hepatoprotective function of the extract from both the growing and regenerating liver containing a natural set of factors crucial for the hepatic restoration. Extracts from both regenerating liver of rats after 70% hepatic resection and the growing liver of neonatal pigs were obtained using own original technique. The set of resultant extracts was named as the hepatic regeneration set (HRS). HRS fractionation was carried out using the Toyopearl HW-50S sorbent. The efficiency of HRS and its fractions was estimated using a model of the mouse liver thioacetamide injury and monitoring hepatic enzyme activity in blood serum. The activities of AST and ALT in intact animals were 50 U/l and 80 U/l, respectively; after thioacetamide administration they increased to 2059±212 U/l and 4280±440 E/l, respectively (p<0.05). Treatment of injured animals with HRS from the rat regenerating liver resulted in a significant decrease of transaminase activities to 924±148 U/l (AST; p<0.05) and 1633±308 U/l (ALT; p<0.05). A similar effect was observed after treatment with HRS from the neonatal pig liver: the AST decreased to 937±138 U/l (p<0.05), while ALT activity decreased to 1710±237 U/l (p<0.05). HRs fractionation resulted in identification two active fractions characterized by much higher (8-29) hepatotropic effect that that of the whole extract. These fractions contained peptide/protein components with the range of molecular mass of 3-60 kDa (fraction 1) and 3-25 kDa (fraction 2a). Fraction 1 also contained some polynucleotides in fraction 1. Subsequent studies of these fractions exceeding the hepatotropic effect of original HRS is clearly needed to identify their individual components by immunochromatography methods, ELISA, MRM mass spectrometry and quantitative PCR.

Effects of preconditioning on the resistance to acute hypobaric hypoxia and their correction with selective antagonists of nicotinic receptors.

Hypobaric hypoxic preconditioning increased the resistance of low resistant and highly resistant rats to acute hypobaric hypoxia at a critical height. Intergroup differences in the resistance of rats to acute hypobaric hypoxia were not observed after hypobaric hypoxia and one variational series with a wide range of resistance (4.5-24.5 min) appeared. Methyllycaconitine, an antagonist of subtype α(7) nicotinic cholinergic receptors, abolished the influence of hypobaric hypoxia on low resistant rats, but had no effect on highly resistant animals. Mecamylamine, a preferential antagonist of subtype α(4)ß(2) and α(3)-containing cholinergic receptors, did not modulate the effect of hypobaric hypoxia. By contrast, hypobaric hypoxia abolished the effect of mecamylamine on the resistance of rats that were not trained under conditions of hypobaric hypoxia (low resistant and highly resistant animals with low sensitivity to hypobaric hypoxia). We conclude that the same effect of hypobaric hypoxia is mediated by various mechanisms, which involve different nicotinic cholinergic receptors. They differ from the resistance mechanisms in non-trained rats.

Chronic cerebral ischaemia forms new cholinergic mechanisms of learning and memory.

The purpose of this research was a comparative analysis of cholinergic synaptic organization following learning and memory in normal and chronic cerebral ischaemic rats in the Morris water maze model. Choline acetyltransferase and protein content were determined in subpopulations of presynapses of "light" and "heavy" synaptosomal fractions of the cortex and the hippocampus, and the cholinergic projective and intrinsic systems of the brain structures were taken into consideration. We found a strong involvement of cholinergic systems, both projective and intrinsic, in all forms of cognition. Each form of cognition had an individual cholinergic molecular profile and the cholinergic synaptic compositions in the ischaemic rat brains differed significantly from normal ones. Our data demonstrated that under ischaemic conditions, instead of damaged connections new key synaptic relationships, which were stable against pathological influences and able to restore damaged cognitive functions, arose. The plasticity of neurochemical links in the individual organization of certain types of cognition gave a new input into brain pathology and can be used in the future for alternative corrections of vascular and other degenerative dementias.

[The regulatory role of mitochondrial dysfunction in hypoxia and its interaction with transcription activity].

The mitochondrial respiratory chain participates in the performance of the signal system, which activates the realization of metabolic compensatory processes and coupled functional response to both single and repeated, long-term exposure to acute hypoxia. Under the conditions of reduced oxygen delivery to cells the mitochondrial respiratory chain is involved in the process of oxygen homeostasis regulation and modulates oxygen consumption, the rate of oxygen delivery from the extracellular milieu to mitochondria, and energy synthesis, activating hypoxia-specific transcription factors as well.

Effect of intermittent normobaric hypoxia on kinetic properties of mitochondrial enzymes.

We studied the effect of intermittent normobaric hypoxia on the formation of adaptive signs and state of mitochondrial enzymes in the cerebral cortex of rats with different resistance to hypoxia. Kinetic parameters for mitochondrial enzymes in the substrate region of the respiratory chain of the cerebral cortex underwent various changes in low resistant and highly resistant rats over the first 2 h after 1-h intermittent normobaric hypoxia. Low resistant animals were characterized by more effective functioning of rotenone-sensitive NADH-cytochrome C reductase and succinate-cytochrome C reductase under conditions of increased reduction status of the cell. These features correlated with the increase in the general resistance of animals. Significant changes in kinetic properties of mitochondrial enzymes and signs of the development of resistance were not found in highly resistant rats. Reciprocal relations between mitochondrial enzyme complexes in the substrate region of the respiratory chain probably play a role of the signal regulatory mechanism, which mediates tissue-specific and general resistance of rats under conditions of intermittent normobaric hypoxia. These effects did not depend on oxygenation of the inhaled gas mixture during the inter-hypoxic period.

Parameters of adenylate pool as predictors of energy metabolism disturbances in hepatocytes during hypoxia.

We studied the dependence of various parameters of adenylate pool in hepatocytes on oxygen concentrations. Isolated cells responded to a decrease in oxygen content in their microenvironment by changes in components of the adenine nucleotide system, which attested to phasic nature of this process. Three ranges of oxygen concentrations differing by the type of changes in the parameters of adenylate pool were distinguished: steady-state range of these parameters; primary changes in the adenylate pool aimed at minimization of energy losses (compensatory stage characteristic of the initial stages of hypoxia); and linear drop of ATP content paralleled by decompensation of the regulatory mechanisms of ATP formation and adenine nucleotide degradation. Hence, parameters of the adenylate pool can serve as predictors of different stages of hypoxia. Differences in the parameters of adenylate pool depending on the level of O(2) in hepatocytes of rats highly and low-resistant to hypoxia indicate that energy metabolism is a mechanism involved in the formation of individual cell resistance to oxygen deficiency. These data suggest that suspension of isolated hepatocytes as an adequate cellular model for experimental studies of the effects of hypoxia on energy metabolism and functional activity of the cell.

[The action of corticosterone on the macroerg pool and membrane permeability in rat hippocampal slices during hypoxia]. / Deistvie kortikosterona na pul makroérgov i sostoianie membrannoi pronitsaemosti v srezakh gippokampa krys pri gipoksii.

Incubation of rat hippocampal slices for 30 min in medium containing 900, 700, or 500 microM of O2 did not significantly change ATP, ADP, or CP levels, but when O2 content dropped to 100-200 microM the levels of ATP and CP decreased by 2 to 5 times. Under the same conditions CPK maximal solubilization was shown. Corticosterone acetate (CSA, 160 microM) did not show a membranotropic effect, nor did it influence the macroerg pool under conditions of high O2 content, but when O2 concentration was 100 microM a twofold increase of ATP and CP levels was observed. This effect correlated with a twofold increase of CPK membrane permeability. The results of this study permit us consider that membrane labilization is not a reflection of CSA neurotoxic effect in hypoxia. A relationship between CSA antihypoxic effect and macroerg pool increase is discussed.

[Differences in the hormonal status of rats highly and poorly resistant to hypoxia]. / Razlichiia gormonal'nogo statusa u vysoko- i nizkoustoichivykh k gipoksii krys.

Rats were tested for hypobaric hypoxia and decapitated two weeks later at 9-12, 13-14 and 15-17 o'clock. The levels of corticosterone, insulin and testosterone were determined in serum by RIA. Great daily fluctuations and higher elevation of corticosterone level in response to additional 1.5-min hypoxia were observed in low hypoxia-resistant (HHR) rats. The correlation of corticosterone/insulin ratio was directly proportional in LHR rats and inversely proportional in HHR rats. No difference in testosterone and insulin levels in LHR and HHR rats was found.

[Brain bioenergetic parameters in rats with varying resistance to hypoxia]. / Bioénergeticheskie parametry mozga krys s raznoi rezistentnost'iu k gipoksii.

Spontaneous electrical activity, adenyl nucleotides' and cytochromes' contents, activity of respiratory chain enzymes complex in brain slices, homogenate and isolated mitochondria of rats, preliminary divided into non-resistant (NR) and high resistant (HR) animals by their sensitivity to hypobaric hypoxia have been investigated. It has been shown that in HR animals brain slices high resistant to hypoxia neurons and in NR brain slices non-resistant neurons predominate. ATP content and energetic charge in the HR animals brain slice were maintained at more high level than in NR. The reduction of NAD-depended way of oxidation in low pO2 conditions was greater in brain of NR than in HR animals. Activity of NADH-cytochrome C reductase (rotenon-sensitive) and Km for NADH in HR brain was more higher in the comparison with NR. These data indicate the main role of NADH-oxidase way in the formation of the individual brain resistance to hypoxia.

[The content of mitochondrial and microsomal cytochromes in liver tissue in experimental drug-induced fatty hepatosis]. / Izuchenie soderzhaniia mitokhondrial'nykh i mikrosomal'nykh tsitokhromov v tkani pecheni pri éksperimental'nom lekarstvennom zhirovom gepatoze.

Fatty tetracycline-induced steatosis is shown to reduce levels of mitochondrial and microsomal cytochromes. A decrease of microsomal cytochromes in the liver of hypoxia-resistant animals was similar to that of hypoxia-sensitive ones. This decrease was different for hypoxia-resistant and hypoxia-sensitive animals: for the former only cytochrome a declined, in the latter case cytochromes c+, c1 and a.

[The correlation of energy-consuming and energy-synthesizing reactions in rat hepatocytes in different O2-deficient states]. / Sootnoshenie énergopotrebliaiushchikh i énergosinteziruiushchikh reaktsii v gepatotsitakh krys pri raznykh O2-defitsitnykh sostoianiiakh.

It is shown that rat liver cells have different sensitivity to oxygen deficiency. Hepatocytes of highly resistant animals have higher viability and maintain higher ATP levels during acute hypoxia. The data obtained enable us to suppose that liver cells of highly resistant rats are more resistant to oxygen deficiency than nonresistant ones.

[Characteristics of ultrastructure of the myocardium of rats with different resistance to oxygen deficiency after acute and periodic effects of hypoxia]. / Osobennosti ul'trastruktury miokarda krys s raznoi rezistentnost'iu k kislorodnoi nedostatochnosti posle ostrogo i periodicheskogo vozdeistviia gipoksii.

In experiments on rats with different resistance to oxygen deficiency (high-resistant--HR, and low-resistant LR animals) the myocardium ultrastructure of nonadapted and adapted rats was studied. It was shown that there were more glycogen granules and lipid drops initially in cardiomyocytes of nonadapted HR animals in comparison with LR ones. After a long-term adaptation to hypoxia the hypertrophia and hyperplasia of mitochondria, the nucleus and endoplasmatic reticulum hypertrophy were observed. Moreover, the increase of glycogen and lipids content was more pronounced in the myocardium of LR rats. Besides, the activation of protein-synthesizing processes was observed not only as a result of long-term adaptation, but also after single acute hypoxic effect. The results of submicroscopic cardiomyocyte studies of HR and LR rats are in good correlation with the peculiarities of energetic metabolism.

[Energy regulation of transmembrane potentials in liver cells during hypoxia]. / Energeticheskaia reguliatsiia transmembrannykh potentsialov kletok pecheni pri gipoksii.

The influence of oxygen tension on values of transmembrane potentials in rat liver cell was investigated. The membrane potential was assessed by the uptake TPP as was determined on the ion-selective electrode. Infusion of inhibitors oxidative phosphorylation and glycolysis to incubation medium caused depolarization on the mitochondrial, and, the plasma membranes of this cell. These and other experimental results suggest that there is an interaction between mitochondrial and cytosol pools of ATP, which determine steady-state values on transmembrane potential liver cell under hypoxia.

Changes in synaptosomal membranes from cerebral cortex due to psychogenic stress in rats.

The changes in synaptosomal membranes in comparison with those of macrophages and mitochondria during repeated psychogenic stress were evaluated using a specially designed multiprobe procedure. Activity of Na,K-ATPase activity was measured as a functional marker for synaptosomal membranes. The interaction of peritoneal macrophages with nitrobluetetrazole (NBT-test) was also evaluated. Some bioenergetic parameters were measured in mitochondria using spectrophotometric techniques. The data revealed profound structural and functional changes in synaptosomal membranes on 15th day of stress. Those in macrophage membranes, present on 3rd and 6th day were not accompanied by functional ones. In conclusion the present data suggest that stress repeated for 15 days leads to a modelled psychopathology in rats and induce selective structural and functional changes in synaptosomal membranes from the cerebral cortex. This model may be used for investigations of the effects of psychotropic drugs.