[The radiotherapeutic effect of the CM-5 fraction of turtle spleen extract]. / Radioterapevticheskii éffekt fraktsii CM-5 ékstrakta selezenki cherepakhi.

CM-5 fraction of tortoise spleen extract injected after irradiation in dose CD50/30 (540 R) raises a survival of mice to 73.4%. The number of endocolonies of spleen increases to 4.0 in experiment against 0.3 in control and the average life of experimental animals increases to 12.7 days against 8.8 in control. In vitro it has been found a considerable increase of RNA-synthetic activity of bone marrow cells stimulated by CM-5 fraction in post-irradiation period. The dose alteration factor for CM-5 fraction is 1.46 according to CD50/30 standard at survival test.

[Effect of freon-114B2 (1,2-dibromotetrafluoroethane) on the seasonal rhythm of energy activity in rat liver mitochondria]. / Vliianie freona 114B2 (1,2-dibromtetraftoretana) na sezonnyi ritm energeticheskoi aktivnosti mitokhondrii pecheni krys.

In the experiments with white rats it was found, that the inhalation of freon 114B2 at CL16, CL50, CL84 levels caused the changes in seasonal values of the energy activity in mitochondria. The action of the freon 114B2 caused disturbances in regulation of the mitochondria activity and desynchronization of seasonal rhythms of their energy activity.

[Oxidative phosphorylation and lipid peroxidation of the liver mitochondria in rats after acute benzene poisoning]. / Okislitel'noe fosforilirovanie i perekisnoe okislenie lipidov mitokhondrii pecheni krys posle ostroi benzol'noi intoksikatsii.

The study revealed that after benzene-induced intoxication (CI50) there occurred low-energetic and energetic phase shifts in rats' liver mitochondria. The content of lipid peroxidation products of the above organellas varied analogously. The time following intoxication being longer, higher were the general level of liver mitochondria energetic activity and the content of lipid peroxidation products. The highest level was recorded on the 3d day after benzen-induced intoxication. On the 16th day complete recovery of liver mitochondria was not recorded.

[Effect of a tortoise spleen extract on the functional state of liver mitochondria in irradiated mice]. / Deistvie selezenochnogo ékstrakta cherepakh na funktsional'noe sostoianie mitokhondrii pecheni obluchennykh myshei.

A study was made of the effect of a drug prepared from a spleen extract of Testudo horsfieldi on energy metabolism and lipid composition of liver mitochondria of irradiated mice (2.06 X 10(-1) C/kg). It was shown that the decompensated low-energy state of liver mitochondria of the exposed mice was changed into the state of the compensated low-energy shift: the physicochemical properties of lipid microenvironment of mitochondria proteins were partially restored.

[Electric parameters of the L-type horizontal cell layer in the carp retina]. / Elektricheskie parametry sloia gorizontal'nykh kletok L-tipa v setchatke karpa.

The inner longitudinal resistance of the L-type horizontal cell syncytium in the carp retina ranges from 1.5 X 10(5) to 7,4 X 10(5) Ohm. The static resistance of the nonsynaptic membrane at the potential level corresponding to the bright light ranges from 2,5 X 10(3) to 19 X 10(3) Ohm . cm2 i.e. comparable with membrane resistances of many neurons recently investigated. Depolarization increases the resistance in 3,5 divided by 21 times up to 16 X 10(3) divided by 69.10(3) Ohm . cm2. Measured values of the capacity are 1 divided by 2 mcF . cm-2.

[Influence of various agents on the magnitude of intracellular local changes of resistance]. / Vliianie vozdeistvii na velichinu vnutrikletochnykh lokal'nykh izmenenii soprotivleniia.

The effect of local changes of resistance that was earlier described in horizontal cells and muscle fibres appears in response to the changes of membrane potential. The local resistance decreased with depolarization and increased with hyperpolarization. In experiments on musculus sartorius of the frog it is shown that the magnitude of the effect increased with cooling to 0 degrees C and reversibly abolished with warming to 30--35 degrees. The effect of local changes of resistance was diminished also by ethanol (5%) and with the increase of pH of perfusing solution to 9--10, the decrease of pH to 3,5--4 increased the effect. Preincubation of the muscle in solution containing colchicine or dinitrophenol did not abolish the effect of local changes of resistance. The nature of the structure responsible for the effect is discussed.

[Ionic metabolism in the horizontal cells of the retina]. / Osobennosti ionnogo obmena v gorizontal'nykh kletkakh setchatki.

According to the experimental data, the membrane potential of L-type horizontal cells in the bright light (i.e. when the input synapses are completely closed) is close to the potassium equilibrium potential. Basing on this fact the intracellular concentrations of K+ and Na+ ions are estimated. The latter proved to be relatively high (several tens mM) and comparable with intracellular concentration of potassium ions. This result in combination with the proximity of the light response equilibrium potential to zero level demonstrates that not only sodium conductance of a synaptic membrane but also potassium one take part in generation of light response. It is shown that stationary sodium and potassium synaptic currents are relatively weak and their variation within a working range of the membrane potentials (from -72 to -16 mV) is rather small. This stabilization of synaptic currents results from nonlinear properties of a nonsynaptic membrane of horizontal cells.

[Intracellular local changes of resistance in muscle fibers in relation to membrane potential]. / Vnutrikletochnye lokal'nye izmeneniia soprotivleniia v myshechnykh voloknakh v zavisimosti ot membrannogo potentsiala.

Intracellular local changes of resistance in sartorius muscle of the frog were investigated. The changes of resistance that were earlier shown to be located very near to the tip of the microelectrode appear in response to the changes of membrane potential evoked in various ways: polarization with electric current, depolarization with increase of the extracellular [K+], generation of action potentials. Depolarization leads to the local decrease of resistance, hyperpolarization--to increase of it. By using the tree-barreled microelectrodes with various geometry of the cross section, an attempt was undertaken to check some spatial peculiarities of the structure responsible for the local changes of resistance.

[Ionic mechanisms of the nonlinearity of retinal horizontal cell membranes]. / Ionnye mekhanizmy nelineinosti membrany gorizontal 'nykh kletok setchatki.

Changes in ionic conductivity underlying the nonlinearity a voltage-current curve of the nonsynaptic membrane of horizontal cells were investigated in experiment on goldfish and turtle retina. The measurements were made under conditions when conductivity of a subsynaptic membrane was minimal, i.e. when the retina was illuminated with bright light or synaptic transmission from photoreceptors was blocked with Co2+. An increase in [K+] led to depolarization and diminution os steepness i a hyperpolarizing part of the voltage-current curve; a decrease in K+ evoked an opposite effect. A decrease in [C1-] did not change both the membrane potential and the shape of the voltage-current curve. Substitution of Na+ by tris or choline did not evoke a reliable change in the membrane potential, and produce only a slight change in the shape of he current-voltage curve. It is concluded that the membrane is permeable for K+; permeability for C1- is absent or small; permeability for Na + is small too. Ba2+ (2-5 mM) increased the steepness of the hyperpolarizing part of the voltage current curve, and the curve became more linear. It is concluded that the nonlinearity is determined mainly by potential-dependent k+-channels whose conductivity increases with hyperpolarization, and Ba2+ blocks this increase in permeability. An increase in Ca2+ from 1 to 20 mM enhanced the steepness of the depolarizing part of the voltage-current curved without altering the hyperpolarizing part. It is supposed that the horizontal cell membrane has potential-dependent Ca2+- channels whose conductivity increases with depolarization.

[Study of the electrical properties of retinal horizontal cell syncytia by the technic of uniform polarization]. / Issledovanie élektricheskikh svoistv sintsitiia gorizontal'nykh kletok setchatki metodom odnorodnoi poliarizatsii.

For uniform polarization of syncytial or cable structures at a large area with current passed via extracellular electrodes the extracellular longitudinal gradient of potential must be proportional to distance from the edge of preparation. In this paper the profile of conducting plate was found analytically which allows to obtain such a distribution of potentials. The profile is formed by hyperbola and its orthogonal asymptotes. Two polarizing electrodes are applied to places where the hyperbola is near to asymptotes. On the surfaces formed by asymptotes the gradient of potential is proportional to distance from intersection of these surfaces. Such a conducting plate was made as cavity in plexiglas filled by Ringer solution in agar. The plate was used for obtaining the voltage-current curves of horizontal cell membrane in gold fish retina. The area of uniform polarization was 4-5 mm long. Measurements inside this area allowed to determine the space constant of horizontal cell layer. The space constant measured in bright light (when resistance of subsynaptic membrane is high) depends on the membrane potential, being high (approximately 1,5 mm) during depolarization and low (0,2-0,4 mm) during hyperpolarization.

[Membrane potential clamping in the horizontal cells of the fish retina]. / Fiksatsiia membrannogo potentsiala v gorizontal'nykh kletkakh setchatki ryb.

The membrane potential of horizontal cells was clamped using uniform polarization of a layer of these cells by means of current passed via extracellular electrodes. It is shown that the voltage-current relationship of the nonsynaptic membrane of horizontal cells has in some cases sections with a negative slope. With fast shifts in the clamped potential level the changes in the membrane resistance are completed less than for 20 ms. Comparison of responses to light stimulation recorded with potential clamp and without it showed that participation of the nonsynaptic membrane in generation of responses to light stimulation can change significantly the form of the latter.

[Changes in the distribution of synaptic vesicles in cone endings following electrical stimulation of the retina]. / Izmenenie respredeleniia sinapticheskikh puzyr'kov v okonchaniiakh kolbochek pri élektricheskoi stimuliatsii setchatki

The conditions were found (hypoxic state of the retina) under which exhausture of the transmitter in presynaptic endings of photoreceptors may be supposed from a decrease in responses of horizontal cells to electric stimulation of the retina. Under these conditions the electric stimulation is accompanied by a decrease in the number of small synaptic vesicles near the presynaptic membranes in cones. However, there are no reliable changes in the total number of vesicles in cone endings.

[The non-synaptic membrane of the retinal horizontal cells as an amplifier of slow potentials]. / Nesinapticheskaia membrana gorizontal'nykh kletok setchatki kak usilitel' medlennykh potentsialov

A simplified model of the membrane of horizontal cells of L-type is suggested. The model reflects two main features of these cells studied earlier experimentally: 1) their hyperpolarizing response to light results from a decrease in EPSP maintained continuously in the dark; 2) the resistance of nonsynaptic membrane of these cells drops under hyperpolarization within a physiological range (from 0 to 70 mV). The model reproduces such properties of horizontal cells as a low membrane potential in the dark, inversion of the response to light with depolarization above a zero level of the membrane potential, an effect of mutual amplification of colour signals, saturation of the response in the bright light, peculiarities of stationary V-A-characteristics in the dark and in the light, as well as a shape of stationary relations between the membrane potential and light intensity which often have a steep part within a certain range of membrane potentials. The existence of hysteresis loops in V-A-characteristics and relations between the membrane potential and light intensity predicted by the model was confirmed experimentally in horizontal cells of fish retina. The analysis of the model and experimental results show that the nonsynaptic membrane of horizontal cells is able to amplify actively the slow graded potentials.

[Uniform polarization of fibers and syncytial structures by extracellular electrodes]. / Odnorodnaia poliarizatsiia vololcon i sintsitial'nykh struktur vnekletochnymi élektrodami

The method is described which enables to measure the voltage-current relations of the membrane of fibres and of syncytial structures by means of the current passed through the extracellular electrodes. The method is based on such a distribution of extracellular resistances that the polarization of the membrane was uniform on a large area. For this purpose the extracellular longitudinal gradient of potential had to increase linearly as a function of distance from one of the edges of the preparation. Such a distribution of potentials was achieved by passing current along the conducting agar-layer, the thickness of which decreased with distance from the edge. The length of the agar-layer where the longitudinal potential gradient increased must be large in comparison with the space constant. It is shown that in the zone where polarization is uniform the density of the current crossing the membrane is proportional to the current passed through the preparation independently on the membrane resistance. The method was applied for measuring the voltage-current relations of the horizontal cell membrane in the fish retina.