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Activities of the complement classical, alternative and lectin pathways were determined under conditions of X-radiation in the blood of rats treated and none-treated with synthetic Schiffbase aromatic amino acid derivatives, nicotinyl-L-tyrosinate or nicotinyl-L-tryptophanate, before irradiation. In case of activities of the alternative and lectin pathways no significant changes between irradiated animals and none-irradiated control animals were detected. However, the data obtained demonstrate significantly elevated activity of the classical complement cascade in the blood of irradiated animals (1 day after irradiation), as compared to those none-irradiated. This effect was less pronounced in rats treated with nicotinyl-L-tyrosinate or nicotinyl-L-tryptophanate 1 hour before irradiation. Based on the results obtained the ability of nicotinyl-L-tyrosinate and nicotinyl-L-tryptophanate to act as cyto-protectors is concluded.

Earlier we have synthesized new Mn-chelates (Mn-compexes of ethyl ethers of salicyliden-D, L-tyrosine, -gamma-amino butyric acid and -D, L-tryptophan) bearing several free functional groups. The radioprotective and antioxidant activity of these compounds were tested on the secondary cultures of chick embryo cells. To this end the cells in vitro were gamma-irradiated with 60Co at the doses 40 and 60 Gy or treated with H2O2 at the concentration 3 mmol/l, the new Mn-chelates were added into the cultures, and the number of survived cells was determined in 24 hours. It was revealed that all the new Mn-chelates at micromolar concentrations (from 40 to 10 mumol/l) but not their precursors (Mn-acetate and ethyl ethers of salicyliden-aminoacids) effectively protect the cells from lethal effect of both gamma-irradiation and H2O2. Mn-chelates tested are considered as promising potential radioprotectors that effect seems to be reasonable to study in vivo.

The presentation summarizes the results of studies on radioprotective activity of newly synthesized Mn(II) chelate with ethyl ester of salicylydene D,L-tyrosine, basing on the evaluation of its membrane-protective effects, revealed at different periods post the exposure of the organism to ionizing radiation. It was revealed that the administration of the compound into the animal organism before the radiation exposure (gamma-irradiation of 60Co at a dose level of 4.8 Gy) produced correcting action on structure-functional properties of erythrocyte membrane of irradiated rats: the excessive activation of lipid peroxidation of erythrocyte membranes was inhibited, the passive permeability of erythrocytes for K+ ions was normalized, the deformity and membrane potential of erythrocytes according to hydrogen-chlorine gradient were recovered.

The effect of coherent and non-coherent electromagnetic fields of millimetre range on biophysical and biochemical indices of blood erythrocytes and plasma of the animals totally exposed to radiation at various periods of observation (day 1, 5, 10) was studied. The following structure-functional shifts were revealed: deviations in the content of separate phospholipid fractions of erythrocyte membranes, the changes of lipid peroxidation products in erythrocyte membranes and blood plasma of the irradiated animals, statistically significant increase of K ions out-flow from the erythrocytes, as well as the alteration of the value of membrane potential of erythrocytes.

The effects of lethal and sublethal doses of ionizing radiation on structural and functional characteristics of erythrocytes membranes was studied. Statistically reliable increase in K+ escape from cell and decrease in membrane potential. Model membranes made of phospholipids extracted from irradiated membranes exhibit increased ion permeability. Radiation induced changes in some membrane phospholipids content were revealed.

It was found that a drug of the nootropic nature piracetam possessing pronounced antihypoxic properties eliminates calcium chloride-induced disturbances of the cardiac rhythm and significantly raises the threshold of atrial fibrillation during electrical stimulation. The drug's antiarrhythmic effect is followed by a decrease of the rhythm rate and an increase of the contraction amplitude. The animals treated with piracetam in a dose when its antiarrhythmic effects (300 mg/kg) exhibited a decrease of the membrane potential of erythrocytes as compared with control. Similar effects occurred in the animals treated with lidocaine. It can be concluded that in certain types of arrhythmias the use of piracetam restores the normal rhythm of contractions that is perhaps connected with its positive influence on metabolic processes in the myocardium.

The authors studied the properties of prostaglandins to increase the permeability of the model membranes from lecithin, ganglioside and proteolipids by ions of alkaline metals. The permeability was found to correlated with the concentrations of prostaglandins. It was also discovered that prostaglandins are capable of forming cation, primarily, potassium permeability.

PGE1 and PGF2 alpha were shown to exert an opposite action on Na, K-ATPase activity and protein fluorescence of the platelet membranes. The effect of the prostaglandins appeared to be unidirectional as regards the erythrocytic membranes. The prostaglandins were demonstrated to increase viscosity of the lipid bilayer and its permeability by uni- and bivalent cations.

The influence of enkephalin on structural and functional properties of model membranes from cell membrane lipids was investigated. Administration of enkephalin increased the permeability of lecithin and cerebroside membranes for potassium and calcium ions up to three orders. The permeability of the model membranes was discovered to be dependent on enkephalin concentration within the range from 10(-5) to 10(-6) M. Cation specificity, primarily calcium one, of modified lipid membranes was demonstrated. Thermodynamic studies showed that interaction of enkephalin with liposomes was endothermic in nature. The thermal effect of the interaction in the presence of Ca2+ was greater than that in the presence of K+, which is likely to be related to appreciable conformational changes in liposome structure in the environment of calcium. The data obtained suggest that enkephalin is capable of raising the permeability of cell membranes through lipid fractions because of conformational changes in the structure of the membranes under study during their interaction with enkephalin.

Artificial membranes were reconstructed from differently purified proteolipids (PL) of cattle brain white matter. The related lipids had different quantitative (72, 50-45 and 15-8%) and qualitative content. Conductance of the artificial membranes of all three types of PL in 0.1 M solutions of alkaline metal chlorides were 2-3 orders above that of bilayer membrane of lecithin and brain phospholipids. In all the cases the PL membranes with 85-92% protein content had the highest conductance, and those with 28% protein content--the lowest. Introduction of liposomes of PL and lecithin mixture to one side of the bilayer lecithin membrane brought about a gradual increase of its conductance up to a definite high level. The membranes made of all three types have specific conductance to monovalent cations which are arranged in the following order: Na+ greater than K+ greater than Cs+ greater than Li+.

In patients with various impairments of brain circulation a decrease in deformation and osmotic stability of erythrocytes were observed. These findings correlated with the decrease in activity of Na+, K+- and Ca2+-ATPases from the cell membranes. At the same time, the Mg/+-ATPase activity was markedly increased. Conductivity for K+, Na+ and Ca2+ was increased in lipid bilayer of erythrocytes obtained from the patients with brain vascular pathology.

The effect of a new cholinolytic drug ethpenal, that is applied clinically as an antiparkinsonian and antiulcer agent, on the course of experimental myocardial infarction has been studied. The experiments have shown that in the test animals (white rats and rabbits) with myocardial infarction, ethpenal increases by 9.3% the contractile function of myofibrils, makes tissue respiration return to normal, and approximates the P/O magnitude to the control level. Administration of ethpenal to the animals with experimental myocardial infarction induces a considerable increase in the content of polyglycerophosphatides, which, in its turn, leads to stabilization of the cellular membranes. The drug improves permeability of the bilayer lecithin membranes by calcium ions. A conclusion is made that the myocardial infarction, ethpenal exerts a beneficial effect on the processes occurring at a level of the cellular membranes.

The membrane conductivity for K+ and Ca+2 ions was studied on bilayer phospholipid membranes formed by phospholipids extracted from the rat liver 1 hour, 1, 3, 7, and 15 days after burning. A pronounced increase in the membrane conductivity was noted. The most potent effects were seen by the 1t, 3d and 7th day of the experiment and the conductivity value varied depending on the medium pH. The process was accompanied by lipid peroxidation increase. Intraperitoneal administration of alpha-tocopherol at 1 mg/kg dose immediately after burning, followed by injections on the 3d, 7th and 12th day, normalized the characteristics studied. Bilayer membranes formed by healthy rat liver phospholipids previously added with an appropriate amount of methyl oleate or cumylhydroperoxide demonstrated higher conductivity as compared to the normal.

Ionic conductivity of bilayer membranes formed of cerebrosides and sphingomeylins isolated from bovine brains and its dependence on medium pH were studied. It was found that conductivity of the membranes from cerebrosides in KC1, CaCl2 solutions is 2-3 orders, and from sphingomyelin 1-2 orders higher than that of bilayers from lecithin and phospholipids. Both in cerebroside and sphingomyelin membranes the conductivity depended on medium pH, unlike the bilayer membranes of the brain and liver phospholipids.

A decrease in erythrocyte deformation, which was maximum at the height of radiation sickness, was registered as early as 1-3 days following 6 Gy irradiation of rats. The aggregation of erythrocytes increased during the latent period of radiation sickness then sharply decreased. The role of the observed changes in radiation sickness then pathogenesis is discussed. It is established that they are associated with the altered fatty acid composition of the lipid phase of erythrocytic membranes, on the one hand, and with the disturbances in its ionic permeability, on the other.

Electrical conductivity of model membranes of lecithin, cardiolipin, gangliosides and lecithin-gangliosides mixture under the effect of PGE1, PGA1, PGI2 were investigated for a number of ions. Property of prostaglandins to increase membrane conductivity within a wide range of concentrations (10(-5) M--10(-10) M) was discovered. Cation selectivity of the membranes under the effect of prostaglandins was found. Ability of prostaglandins to change conformation of lipid membranes was indicated.

Study of some electric properties of bilayer membranes made of cerebrosides and phospholipid-cerebroside mixture has shown that the capacity of cerebroside film is lower than that of lecithin-cerebroside and phospholipid-cerebroside ones (0.22 +/- 0.01 mkf/cm2 and 0.28 +/- 0.01 mkf/cm2 respectively). The membranes had small cation selectivity. It is stated that conductivity of cations of mixed phospholipid-cerebroside membrane is two orders, and of cerebroside three orders higher than that of phospholipid bilayers. Conductivity of the films under study depends on the medium pH. By means of fluorescent probes cerebrosides were found capable of changing the conformation of phospholipid membranes.