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EFfect of linoleic acid hydroperoxide (I) and Fe++ on viscous elastic properties of cell membranes of Ehrlich ascite carcinoma was studied by the method of K+-dependent swelling. It has been shown that the action of 1 and Fe++ is of similar character, and the effect depends on the incubation time and concentration of agents in the incubation mineral solutions. After 2 h incubation the concentration relationships have two patterns characterized by increased swelling at concentrations 10(-6)-10(-5) M and inhibition of this process at concentrations above 10(-5) M. After 4 incubation only the inhibition effect of observed, which seems to reflect the increase of cell membranes rigidity conditioned by the formation of "joints" resulting from the interaction between the products of lipid peroxide oxidation and membrane macromolecules.

A relationship between lipid peroxide oxidation (LPO) in biomembranes and kinetics of oxygen uptake by intact cells and cells under hypotonic shock in the course of their incubation has been studied. Different effect of bivalent ferrum ions--activators of LPO was found; it depended on cell integrity. In the cells under normal physiological conditions the rate of oxygen uptake was independent of the amount of LPO products, while in the cells placed into hypotonic medium it decreased on the background of LPO intensification as compared to the normal one. Peculiar effects of the LPO products on intact cells seem to be related to spatial disconnection of respiratory centres and to localization of peroxide oxidation reactions.

UV-irradiation of mitochondrial membranes causes formation and accumulation of fluorescing products in the course of incubation, like it takes place during the initiation of peroxide oxidation by the iron--ascorbate system. The rate of the change of mitochondria fluorescence and the level of TBA-products in them do not correlate, which points to the difference in the formation mechanisms of these products in the course of incubation. However, a correlation is observed between the initial fluorescence intensity and the number of TBA-active products in mitochondria, which increases with the increase of the time of UV-irradiation.

It is shown that incubation of EAT cells in the presence of Fe2+ ions caused the threshold decrease of active and capacitance constituents of cell suspension impedance and rate of ion efflux from cells to the isotonic sucrose media, and decrease extent rose with an increase of Fe2+ ion concentration and temperature. A discrepancy between the results described and experimental model system data is discussed.

The rate of fluorescent product formation during the peroxidation of polyunsaturated linolenic acid or egg phosphatidylethanolamine and also during the oxidation of linolenic acid together with a phenylalanine and synthetic phosphatidylethanolamine 1,5--3 times more intensive after previous UV-irradiation of the unsaturated fatty acid. Schiff bases are fluorescent products in amine containing systems which are produced in the reaction of the malonaldehyde with amines. It is possible that fluorochromes produced during the only unsaturated acid oxidation are the result of the radical recombination. Accumulation of the oxidated products determined by TBA-reactive substances does not inevitably correlate with the fluorescent intensity in explored systems.

Light scattering (90 degrees) of Ehrlich ascites tumor and sarcoma 37 cell suspension in the temperature range 25-60 degrees C was studied (heating velocity was 3 grad/min). It is found that the scattering curve has the peak at 46 degrees C and two plots which are typical of phase transitions in the membranes; the first plot in the range 40-46 degrees C is reversible and the second one at 46-51 degrees C is irreversible. It is proposed that 46 degrees is a critical temperature for the membranes structure stability and viability of the studied cells.