[Effects of glycyrrhetic acid on transmitter secretion]. / Effekty glitsirretovoi kisloty na protsess sekretsii mediatora.

The investigation of the effects of glycyrrhetic acid on spontaneous secretion of transmitter from neurotermination of the frog neuromuscular synapses showed that this substance, unlike glycyrrhizic acid, increased the frequency and amplitude of m. e. p. p. in a dose-dependent manner. The effect of glycyrrhetic acid is observed in calcium-free solution which may indicate ability of glycyrrhetic acid to mobilize calcium from inner cell pools. The effects of glycyrrhetic acid, in particular increasing the frequency of the m. e. p. p., testify that glycyrrhetic acid acts on the level of presynaptic membrane.

[Dose-dependent character of the effect of hydrocortisone on energy metabolism of rat thymocytes]. / Dozozavisimyi kharakter vliianiia gidrokortizona na énergeticheskii metabolizm timotsitov krys.

The influence of the hydrocortisone (GC) different doses on rat's thymocytes energetic metabolism was investigated. It has been demonstrated that as the prolonged action of GC in vivo (20 micrograms/kg of mass during 6 d. daily) as the preincubation of thymocytes with 10 microM GC in vitro are cytotoxic, leading to absolute uncoupling of oxidative phosphorylation (OP) and decreasing the rate of DNP-stimulated respiration speed. The injection of GC (20 micrograms/kg mass) at once before 72 hours to killing resulted the OP uncoupling almost on 2,5 time. Short-time action of GC at the same dose before 3 hours to drilling and so the thymocytes preincubation with 1 microM GC stimulated the transport processes on the level of substrate oxidation without the OP uncoupling. Short-time action of GC in vivo caused the inhibition of respiration, if we used glucose as the oxidative substrate, and stimulated the respiration in a presence of pyruvate Na in incubation media.

[The action of defoliants on the energetics of rat liver mitochondria in vitro]. / Deistvie defoliantov na énergetiku mitokhondrii pecheni krys in vitro.

The effect of defoliants butyphos (I), dropp (II), butylcaptacs (III), hinazopin (IV), syhat (V), tetra-n-butylammonium bromide (VI), etrel (VII), gemetrel (VIII), allyl-4-methylpyridinium bromide (IX), 1-amino-cyclopropan-1-carbonate (ACPC) (X) at various concentrations (1 x 10(-5)-2 x 10(-4) M) on respiration, oxidative phosphorylation (OP) and permeability of the inner mitochondrial membrane from rat liver has been studied. It has been established that some of the compounds uncouple OP by increasing the inner mitochondrial membrane permeability for H+ (II) inhibit the respiration in V3 condition and induce less selective permeability for a number of ions (I, III). The other defoliants either induce respiration generally in metabolic states 3 and 4 (IV, VI, IX) or have no effect on the respiration and OP (V, VII, VIII, X). On the whole a good correlation between the common toxicity of the studied preparation (LD50) and their mitochondrial effect has been revealed, therefore the latter can be considered as intracellular "targets" involved in the realization of pesticide action.

[Menadione induction of Ca2+ efflux from the mitochondria and of mediator secretion from the nerve endings]. / Induktsiia menadionom vykhoda Ca2+ iz mitokhondrii i sekretsii mediatora iz nervnykh okonchanii.

It is shown that menadion increases the rate of Ca2+ efflux from mitochondria which decreases in the presence of ditiotreitol. Menadion at concentration of 50 microM induces Ca2+ efflux from mitochondria and its effect on synaptic transmission is discussed.

Disturbances in oxidative phosphorylation in the liver of rats with heliotrine-induced hepatitis and restoration by phosphatidylcholine and ATP.

Acute hepatitis induced by heliotrine is accompanied by uncoupling of oxidative phosphorylation in liver mitochondria. The rate of oxygen uptake during succinate oxidation increased in all metabolic states, while the respiratory control index decreased by 45% because of the greater increase in the respiration rate in state 4 by comparison with that in state 3. Heliotrine poisoning also halved the rate of oxygen uptake in rat liver homogenates in the presence of ascorbate and tetramethylene-p-phenylenediamine. This is indicative of a lowering of cytochrome oxidase activity and of energy metabolism disturbances in rat liver. Preparations of cotton phosphatidylcholine (PC), both purified and as ATP-containing complexes (PC+ATP), as well as ATP alone, reduced the metabolic disorders in liver mitochondria of rats with acute heliotrine-induced hepatitis. The therapeutic effect of these preparations consisted in the restoration of oxidative phosphorylation coupling and of the cytochrome oxidase activity. The effect of PC+ATP was much greater than either PC or ATP alone. In contrast, the commercial preparation, Essential, had no beneficial effect.

[The effect of calmodulin and chlorpromazine on the activity of phospholipases A2 from various sources]. / Vliianie kal'modulina i khlorpromazina na aktivnost' fosfolipaz A2 iz razlichnykh istochnikov.

The effects of calmodulin and chlorpromazine on purified phospholipase A2 preparations from snake venoms: cobra (Naja naja oxiana), echis (Ehis multisquamatus) and Agkistrodon halys halys, as well as on phospholipases A2 from rat liver mitochondria and human platelets were studied. It was shown that within the concentration range of 1-5 microM calmodulin stimulates the phospholipase activity. Chlorpromazine inhibits the activity of these enzymes, the degree of inhibition being different for various phospholipases. Calmodulin was shown to interact with the phospholipases in the absence of exogenous Ca2+. The results obtained indicate that all phospholipases tested are calmodulin-dependent enzymes.

[Low molecular weight peptides from the venom of the giant hornet Vespa orientalis. Structure and function]. / Nizkomolekuliarnye peptidy iada bol'shogo shershnia Vespa prientalis. Struktura i funktsiia.

Three 14-member linear peptides (HR-1, HR-2 and HR-3) capable of degranulating mast cells and thus initiating histamine release were isolated from the venom of the giant hornet Vespa orientalis, using reverse phase high performance liquid chromatography. The complete amino acid sequence of the peptides HR-1 and HR-2 molecules and partial structure of peptide HR-3 were determined, using automatic degradation by the Edman method. It was shown that peptide HR-1 at relatively low concentrations (2-20 micrograms/ml) selectively liberated histamine from rat mast cells and, when taken at higher doses (50-100 micrograms/ml), exerted a non-selective cytotoxic action. Besides, this peptide caused erythrocyte hemolysis, inhibited Ca2+-ATPase with concomitant uncoupling of Ca2+ transport and ATP hydrolysis as well as induced the conductance of lipid bilayer membranes, predominantly for monovalent cations due to the formation of nonspecific single permeability channels.

[Effect of thyroxine in vitro on the transmembrane potential of rat liver mitochondria]. / Vliianie tiroksina in vitro na transmembrannyi potentsial mitokhondrii pecheni krys.

It has been shown in in vitro experiments that a certain latent period after the addition of thyroxine (T4) and triiodothyronine (T3) was necessary for the manifestation of their effects on transmembrane potential (TMP) of the rat liver mitochondria. The duration of the lag-period decreased upon an increase in the concentrations of these hormones, and T4 at a dose of 2.10(-4) M produced a fall in TMP immediately after its addition. The rate of TMP fall was in proportion with the concentrations of thyroid hormones introduced into the cell, with T3 30-40% more effective than T4. It was established that the action of I2 resembled that of thyroid hormones, namely, a fall in TMP, mitochondrial swelling, activation of transhydrogenase Kl was ineffective. It is suggested that the appearance of the lag-period upon the action of thyroid hormones might be explained by the period of time necessary for the formation of the active iodine forms, as well as by the formation of fatty acids (donators of H+) by mitochondrial phospholipases. All these factors lead to TMP fall resulting in decreased formation of sufficient ATP quantities in mitochondria.

[Effect of oxaloacetic acid on hydrogen-calcium metabolism in mitochondria]. / Deistvie shchavelevouksusnoi kisloty na vodorodno-kal'tsievyi obmen v mitokhondriiakh.

It has been shown by using o-phthalic acid--a concurrent inhibitor of the transport of oxalacetic acid in mitochondria that the effect of the latter on the mechanism of 2H+/Ca2+-metabolism is realized at the inner side of the inner mitochondrial membrane. Oxalacetic acid was shown to induce not only the release of Ca2+ ions but also those of strontium and manganese accumulated in the mitochondria (100-150 nmol/mg of protein). Mechanism of the effect of oxalacetic acid on permeability of the mitochondria membranes are discussed.

[Glucose transport inhibition in human erythrocytes by calmodulin antagonists]. / Tormozhenie transporta gliukozy v éritrotsitakh cheloveka antagonistami kal'modulina.

Calmodulin antagonists (tryphtazin, lidocaine, dykain, palmitate) inhibit glucose transport from human erythrocytes. Glucose efflux inhibition is proportional to the concentration of antagonists in the medium and is of uncompetitive character. It is accompanied by a decrease in the maximum transport rate with the unchanged constant of dissociation in the complex: carrier-sugar. Calcium ionophores A23187 and divaleryldibenzo-18-crown-6 eliminated the inhibiting effect of pharmacological agents on glucose transport. The authors think that the glucose transport inhibition under the influence of calmodulin antagonists may be realized through the calmodulin-dependent chain inhibition under the influence of calmodulin antagonists in the carbohydrate transport system.

[Fluorescence proper of phospholipase A2 and orientotoxin from the venom of the giant hornet in the presence of ionic modulators of their membrane activity]. / Issledovanie sobstvennoi fluorestsentsii fosfolipazy A2 i orientotoksina iz iada bol'shogo shershnia v prisutstvii ionov--modulia-torov ikh membrannoi aktivnosti.

The own fluorescence of phospholipase A2 and orientotoxin at interaction of these components from Oriental hornet venom with calcium, strontium, lantan, magnesium ions has been investigated. Ca2+, La3+, Sr2+--activators of phospholipase activity--increase the quantum output of fluorescence. In the presence of Ca2+ the temperature of semitransitional process of thermoinactivation of investigated polypeptides increases by 2 degrees C.

[Effect of different levels of thyroid hormones on the fatty acid composition of lipids from rat liver mitochondria]. / Vliianie razlichnogo soderzhaniia tireoidnykh gormonov na zhirnokislotnyi sostav lipidov mitokhondrii pecheni krys.

The abundance or deficiency of thyroid hormones in rat organism influence the unsaturation and desaturation indices of total lipid fatty acids and phospholipids in liver mitochondria. The most conspicuous changes were observed in the fatty acid composition of the phospholipid fraction. The changes in the structure and function of rat liver mitochondria are considered to be due to alterations in the fatty acid composition of mitochondrial phospholipids.

[Sugar transport regulation in vitro by new calcium ionophores]. / Reguliatsiia transporta sakharov in vitro novymi kal'tsievymi ionoforami.

The influence of calcium ionophores--tenoyltrifluoroacetate (TTFA) and divaleryldibenzo-18-crown-6(divaleryl) on the glucose consumption, D-xylose transport and glycogen content in rat diaphragm was studied. TTFA caused a clear dose-dependent inhibition of carbohydrate transport and glycogenolysis stimulation. Divaleryl, on the other hand, raised glucose consumption, D-xylose transport without influencing glycogen content. Exclusion of Ca++ from incubation medium increased the TTFA inhibiting effect on glucose consumption, decreased its glycogenolytic effect and removed divaleryl induced stimulation of glucose transport. Mechanisms of calcium ionophore action and a possible role of intracellular Ca2+ in carbohydrate transport are discussed.

[Structural and functional characteristics of the sarcoplasmic reticulum membranes of the skeletal muscles in thyrotoxicosis]. / Strukturno-funktsional'nye osobennosti membran sarkoplazmaticheskogo retikuluma skeletnykh myshts pri tireotoksikoze.

A rate of CA2+ accumulation and efficiency of Ca2+-pump were decreased in the fractions of skeletal muscle sarcoplasmic reticulum isolated from rabbits with thyrotoxicosis. Temperature of phase transition in membranes of sarcoplasmic reticulum was changed by 4-5 degrees towards low temperatures. Under conditions of thyrotoxicosis fatty acid composition of total lipids from the sarcoplasmic reticulum fractions was altered as follows: amount of palmitic acid was increased 1.4-fold but oleic and arachidonic acids were decreased 21.8% and 40.5%, respectively. Modification of Ca2+-transport properties in sarcoplasmic reticulum caused by long-term administration of thyroid hormones into animals appears to alter the membrane protein-lipid composition.

[Role of protonophore activity of oxalacetic acid in inducing Ca2+ yield from mitochondria]. / Rol' protonofornoi aktivnosti shchavelevouksusnoi kisloty v indutsirovanii vykhoda Ca2+ iz mitokhondrii.

It has been found earlier in Lehninger's Laboratory [24] that oxidation of endogenous PN mitochondria induced by oxalacetic acid (OAA) brings about the release of accumulated Ca2+. Analysis of possible mechanism of this phenomenon has shown that OAA has protonophore activity on mitochondria and BPM unlike the malate--the product of enzymic reduction of OAA in the presence of NAD . H. OAA-induced permeability of BPM and mitochondria membranes for H+ is observed at pH 7.5-8.0 and is insignificant at pH 7.0 and lower. Possible function of OAA as a soft uncoupler-protonophore controlled by metabolism is discussed, in particular--in connection with Ca2+ transport in mitochondria.

[Effect of tenoyltrifluoroacetone on the functioning of mitochondria and other membrane structures]. / Deistvie tenoiltriftoratsetona na funktsii mitokhondrii i drugikh membrannykh obrazovanii.

The effects of tenoyltrifluoroacetone (TTFA) on respiration and oxidative phosphorylation of rat liver mitochondria and on the permeability of inner mitochondrial membranes for mono- and divalent cations were studied. It was shown that TTFA, beside being an inhibitor of succinate oxidation and oxidative phosphorylation uncoupler increases the permeability of mitochondria, sarcoplasmic reticulum fragments, liposomes and bilayer phospholipid membranes for Ca2+. The TTFA (150 mkM)-induced permeability of mitochondria for various cations decreases in the following order: Ca2+: H+: Mg2+: Sr2: Ba2+: K+: Na+ = 1:0,07: 0,06: 0,02: 0,015: 0,01. TTFA predominantly stimulates the Ca2+/H+ or Ca2+/Na+ exchange; the membrane-active effects of TTFA are enhanced in the presence of the hydrophobic anion tetraphenylborate and the neutral electron-donating compound tributylphosphate.

[Effect of thyroid hormones on the calcium pump in sarcoplasmic reticulum]. / O vliianii tireoidnykh gormonov na kal'tsievyi nasos sarkoplazmaticheskogo retikuluma.

In vitro thyroxine inhibited accumulation of Ca2+ by fragments of sarcoplasmic reticulum, isolated from rabbit sceletal muscles. The inhibitory effect of thyroxine was responsible for its direct action on Ca2+ dependent ATPase. Half-maximal inhibition of the enzymatic activity occurred at the same concentrations of thyroxine using both membrane-bound and highly purified solubilized forms of Ca2+-ATPase (15--20 micrometer and 10 micrometer of the hormone, respectively). Triiodothyronine was similar in the effect but not diiodothyrosine, which did not possess the hormonal activity. The data obtained suggest that thyroid hormones affect the mechanism of dephosphorylation in ATP-hydrolase reaction.