[Nature of the recognition system of uterine cell plasma membranes for estradiol].

The interaction of 3H-estradiol and 3H-corticosterone with plasmatic membranes of the rat uterine cells was investigated. It was revealed that accumulation of estradiol in plasmatic membranes was conditioned by two processes: by the binding with highly specific glycoprotein membrane structures and by estrogen diffusion into the lipid membrane phase. At the same time, accumulation of corticosterone is determined exclusively by its penetration into the lipid matrix of plasmatic membranes of the rat uterine cells.

[Characteristics of the system of corticosterone binding by hepatocyte plasma membranes].

Parameters of hepatocyte accumulation of corticosterone and its binding by the plasmatic membranes of these cells are equally changed under the action of membrane-active enzymes, p-chloro-mercury-benzoate, low and high temperatures and 2,4-dinitrophenol on the cells and membranes. It is concluded, that the specific formations of the glycoprotein nature ("recognizing systems"), responsible for the primary recognition, binding and transmembrane tropic hormone transport to the liver, are localized in the membrane.

[5'-Nucleotidase as an "internal probe" in studying steroid hormone interaction with the plasma membranes of target cells].

Changes in the activity of 5'-nucleotidase, the marker enzyme of plasma membranes, in membrane cells of the uterus and liver were examined upon action of tropic and nontropic steroid hormones. In case of tropic steroids, the curves of changes in the activity with rise in the hormone concentration are complicated and broken with a marked minimum at 10(-8) M. Upon the action of nontropic hormones there takes place a monotonous rise in the enzymatic activity.

[Presence of estrogen-binding systems in the plasma membranes of rat uterus cells].

Steroid hormone binding by plasma membranes of rat uterine cells was studied. Estradiol and estriol were shown to be bound by a specific-saturated membrane component with a high affinity for estrogens. Netrophic corticosterone and testosterone interacted with an unsaturated membrane component.

[Reaction between steroid hormones, the liver and its plasma membrane].

The existence of two systems of steroid (corticosterone, estradiol and testosterone) incorporation into hepatocytes and binding by plasma membranes has been demonstrated. One of the systems is specific (saturated), since it binds and incorporates the hormones only in physiological concentrations. Affinity of this system for corticosterone is much higher than that for estradiol and testosterone.

[Characteristics of the steroid hormone binding system in hepatocyte plasma membranes].

Parameters of cortisone and estradiol binding to plasmatic membranes of rat hepatocytes were studied by liquid scintillation radiometry. Two systems of binding these hormones were revealed in the membranes. One of the systems is specific (saturated) and binds the hormones in physiological concentrations.

[Effect of estradiol and tocopherol on peroxidation of erythrocyte membrane lipids following ultraviolet irradiation].

The effect of the antioxidants estradiol and tocopherol on the lipid photoperoxidation in the erythrocyte membranes of rats under UV-irradiation was investigated. Both agents are shown to inhibit the release of potassium ions and hemoglobin provoked by UV-rays, estradiol activity being higher as compared to that of tocopherol. High activity of estradiol is due to the fact that this antioxidant does not lose its antiradical properties when its molecules are exposed to UV-irradiation.

["System of recognition" (or "system of preference") for corticosteroids in the hepatocyte plasmatic membrane].

By using fluorescent probes it was shown that hydrocortisone, cortisone and estron decrease the constant of the probe binding with dimethylaminochalcone in the lipid membranes proportional to the distribution coefficient of steroids in the system lipids-water. It is only hydrocortisone and, to a lesser extent, cortisone which produce such an effect in the plasmatic membranes of the hepasytes. The presence of a "preference system" for corticosteroids is presumed in the membranes.

[Effect of estrogens on interaction of calcium ions with mitochondrial membranes].

It has been shown that steroid hormones do not affect the fluorescence parameters in solutions of the complex NADH-Ca. Addition of discoupling concentrations of Ca2+ to the liver mitochondria induced the elimination of pyridine nucleotides. The hormones studied inhibit the oxidation of NAD-dependent substrates, thus suppressing an active transport of Ca2+.

[Use of the fluorescent probe method to study the interaction of barbiturates with biological membranes].

The binding of the negatively charged fluorescence dye ANS and neutral dye NPN2 with lipid and erythrocyte membranes in the presence of barbiturates was studied. It was found that barbiturates decreased the amount of binding sites of ANS and NPN2 with membranes did not affect the quantum yield and the dissociation of the membrane-dye complex. It was shown that all barbiturates investigated were bound with the membranes in a neutral form.