Impact of 13(S)-HPODE,a lipoxygenase product of linoleic acid,on calcium transport and Na,K-ATPase activity in the myocardial sarcolemma

In thisin vitro study using a purified sarcolemmic fraction of guinea pig myocardium, the 13(S)-hydroperoxide of linoleic acid (13-HPODE) increased in a dose-dependent manner the permeability of myocardial sarcolemma to Ca ions in concentrations above 10 μmol/liter, stimulated Na/Ca exchange there in concentrations from 0.1 to 10 μmol/liter, and exerted a digitalis-like action on sarcolemmic Na,K-ATPase in concentrations between 0.1 and 100 μmol/liter (IC₅₀=20 μmol/liter). The results indicate that the linoleic acid hydroperoxide may be an effective modulator of sarcolemmic Ca²⁺ transport and of membrane-bound enzymes. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 9, pp. 255–257, September, 1995 Presented by D. F. Chebotarev, Member of the Russian Academy of Medical Sciences     

Effects of the nootropics piracetam and GVS-111 on voltage-dependent ion channels of neuronal membranes

The effect of two nootropics, piracetam and N-phenylacetyl-L-prolyglycine ethyl ester (GVS-111), is studied by measuring high-threshold K⁺ and Ca²⁺ currents in isolated snail neurons using a two-microelectrode patch-clamp technique. Piracetam and GVS-111 are shown to reduce the amplitude of both the K⁺ and the Ca²⁺ (to a lesser extent) current. The threshold concentrations for GVS-111 and piracetam are 10⁻⁹-10⁻⁸ M and 1–5×10⁻⁴ M, respectively. It is assumed that the antiamnestic effect of the nootropics is partially mediated by a blockade of ion channels of the neuronal membrane. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 2, pp. 151–155, February, 1996 Presented by G. N. Kryzhanovskii, Member of the Russian Academy of Medical Sciences     

Effect of vinpocetine on various types of high-threshold potassium currents in snail neurons

A high-threshold (−20 mV) K⁺ current was recorded from isolated edible snail neurons by a two-microelectrode voltage clamp technique. This current consisted of three components: fast-inactivating K⁺ currents (I_A), noninactivating K⁺ current (I_KD), and Ca²⁺-dependent K⁺ current (I_K(Ca)). Different cells had one to three components of K⁺ current. Vinpocetine increased I_A, moderately inhibited I_KD (by 30–50%) and strongly suppressed I_K(Ca) (by 60–90%). Inhibition of I_K(Ca) was not related to the effect of vinpocetine on the inward Ca²⁺ current. When K⁺ current consisted of all three components, the effect of vinpocetine on the ionic current amplitude was opposite at different potentials. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 10, pp. 408–411, October, 1998     

The role of the lymphatic system in the changes of electrolyte balance in the febrile reaction

The shifts of the electrolyte level in the lymph and blood are of the same direction, namely, increased. The content of potassium, sodium, and calcium changes only after prolonged fever, while that of magnesium changes after just a single administration of pyrogenal. The lymph level of calcium and magnesium rises more significantly as compared to the blood. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 2, pp. 174–176, February, 1994     

Is Na,K-ATPase the target of oxidative stress?

The susceptibility of Na,K-ATPase from bovine brain to various compounds containing active oxygen radicals is assessed. Sodium nitroprusside slightly inhibits Na,K-ATPase, while light-induced NO^o radicals (controlled by the rate of ascorbate oxidation) have no effect on the enzyme. When added in concentrations equally effective in the ascorbate oxidation assay, hydrogen peroxide and sodium hypochlorite inhibit Na,K-ATPase by 70 and 25–30%, respectively. The Fe-dinitrosyl-cysteine complex is the most potent (K_0.5=20 μM) inhibitor of Na,K-ATPase. It is demonstrated that different free oxygen radicals accumulated in the ischemic brain cause different kinds of damage to Na,K-ATPase. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 3, pp. 275–278, March, 1996 Presented by I. P. Ashmarin, Member of the Russian Academy of Medical Sciences     

Chemiluminescence study of the contents of the products of Cu2+-induced lipid peroxidation in different fractions of human blood lipoproteins

It is demonstrated that the content of the primary products of lipid peroxidation reaches the maximum after about 1-h incubation with Cu²⁺ and then declines. At a Cu²⁺ concentration of about 10–15 μM, the content of lipid peroxidation products is maximal; it does not rise with a further increase in the Cu²⁺ concentration. Comparison of the kinetics of lipid peroxidation in different lipoprotein fractions shows that low density lipoproteins are much more strongly oxidized than high density lipoproteins. A strong positive correlation between the amplitude of the chemiluminescence burst and the diene conjugate content is established in 79 independent measurements. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 2, pp. 144–148, February, 1995     

Inhibitory effect of C-reactive protein on streptolysin O-mediated hemolytic activity. Comparison of conformational variants

It is shown that C-reactive protein binds to streptolysin O, an exotoxin of hemolytic streptococcus, and neutralizes its hemolytic activity. Incubation of C-reactive protein with the working dose of streptolysin O for 15–20 min at 37°C abolished the hemolysis of subsequently added erythrocytes. The concentration of C-reactive protein that reduced hemolysis by 50% was on average equal to 2.28±0.19 μg/ml. C-reactive protein antihemolytic activity was not affected by blocking of its phosphorylcholine-specific sites with free phosphorylcholine, but decreased as a result of blocking with pneumococcal C-polysaccharide and, particularly, with L-α-phosphatidylcholine. This indicates a hydrophobic nature of C-reactive protein-streptolysin O interaction. C-reactive protein subunits retained antihemolytic activity, while the aggregated C-reactive protein lost part of it. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 5 pp. 506–509, May, 1995 Presented by A. A. Totolyan, Member of the Russian Academy of Medical Sciences     

Mechanism of action of the new cardiotonic suphan on calcium exchange in cardiomyocytes

Effects of suphan, a new cardiotonic agent containing succinyl tryptophan, on the entry of Ca²⁺ into rat cardiomyocytes, its intracellular compartmentalization, and its exit from these cells were evaluatedin vitro. It was found that the recorded sulfan-induced rise of intracellular calcium was due to Ca²⁺ entering the cell via L-type calcium channels, and that a reversible reduction of its concentration in the sarcoplasm occurred through its accumulation in the sarcoplasmic reticulum and was blocked by the specific Ca²⁺-ATPase inhibitor thapsigargin (10 μM). Suphan did not alter the activity of Na⁺/Ca²⁺ exchange in a concentration range of 5–150 μg/ml. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 7, pp. 57–59, July, 1996     

Mechanisms responsible for the resistance of tracheal smooth muscle to histamine in rats

A mechanographic study of contractile responses by tracheal smooth muscle segments of rats to a histaminergic agent showed that intact segments did not respond to histamine in the concentrations used (0.01–10 μM), whereas depolarized segments responded to histamine by dose-dependent contraction which were considerably enhanced following mechanical removal of the tracheal epithelium. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 9, pp. 263–264, September, 1995     

Polyunsaturated phosphatidylcholine micelle-induced decrease of atherogenicity of the serumin vitro

It is shown that polyunsaturated phosphatidylcholine administered in micelles stabilized by a plant-derived glycoside prevents the accumulation of cholesterol by cells incubated in atherogenic serum and, moreover, in certain cases causes a 1.4–1.5-fold drop of intracellular cholesterol as compared to control cells. The optimum antiatherogenic effect was achieved when using a micelle concentration of 100–200 μg/ml and an incubation time of at least 4 hours. The antiatherogenic effect was analogous to the effect of high density serum lipoproteins. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 5 pp. 497–501, May, 1995 Presented by Yu. M. Lopukhin, Member of the Russian Academy of Medical Sciences     

Central opioid receptors in the pathogenesis of adrenal arrhythmias

The effect of intraventricular administration of opioid peptides on the frequency and severity of ventricular arrhythmias is studied after intravenous injection of epinephrine. It is found that the selective μ-agonist DAGO and the nonselective σ-agonist DADLE decrease the frequency and severity of arrhythmias. On the other hand, the selective σ-agonist DSLET and the κ-agonist dinorphine A 1–13 potentiate adrenal arrhythmias. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 9, pp. 241–243, September, 1994 Presented by R. S. Karpov, Member of the Russian Academy of Medical Sciences     

Inhibition of platelet aggregation by monoclonal antibodies against glycoprotein IIb–IIIa complex

Monoclonal antibodies CRC64 are obtained against Ca²⁺-dependent glycoprotein IIb–IIIa complex of the platelet membrane which possess the ability to inhibit completely fibrinogen-dependent platelet aggregation. CRC64 is directed against the epitope formed by the glycoprotein IIb–IIIa complex and does not interact with proteins isolated after platelets are treated with ethylenediamine tetraacetate. Complete, reproducible blockade of platelet aggregation caused by 5 μM adenosine diphosphate is noted in an MCA concentration of 3 μg/ml, while in the case of a stronger inductor, namely 1 U/ml thrombin, platelet aggregation is inhibited in a concentration of 5 μg/ml. F(ab′)₂ fragments are also able to inhibit platelet aggregation completely and are usually effective in concentrations lower than native monoclonal antibodies. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 10, pp. 402–405, October, 1994 Presented by V. N. Smirnov, Member of the Russian Academy of Medical Sciences     

Regeneration of the liver after partial hepatectomy with a beam of ionized plasma

Eighty guinea pigs underwent resection of the left lateral lobe of the liver, performed with a beam of ionized plasma. Morphological analysis 32 and 45 hours after partial hepatectomy revealed minor damage to the parenchyma to a depth of 300–400 μ. Autoradiography showed proliferative activity in the organ to occur in the early post-operative period. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 4, pp. 431–432, April, 1995 Presented by B. T. Velichkovskii, Member of the Russian Academy of Medical Sciences     

Contribution of arachidonic acid cycle enzymes to platelet activation by low-density lipoproteins

The mechanism of platelet activation by low-density lipoproteins (LDL) was studied using inhibitors of arachidonic acid cycle enzymes. Lipoxygenase and cyclooxygenase inhibitors (indomethacin, acetylsalicylic acid, NDGA, and BW755C) inhibited LDL-induced platelet aggregation to a small extent, as was indicated by mere 20% to 30% decreases in the maximal rate of change in light transmission. 4-Bromophenacyl bromide inhibited LDL-induced platelet aggregation in a dose-dependent, manner, almost complete inhibition occurring at concentrations in excess of 20 μM. The results support the conclusion that enzymes to the arachidonic acid cycle do not contribute substantially to platelet activation by LDL. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 10, pp. 376–379, October, 1995 Presented by Yu. M. Lopukhin, Member of the Russian Academy of Medical Sciences     

Diurnal time course of hexenal narcosis in experimental hepatosis

A statistically significant circadian rhythm of hypnogenic effect of hexenal is revealed in intact Wistar rats, with the maximum recorded in the daytime and the minimum at night, and an amplitude of at least 30% of the mesor. Circadian rhythms of the analgetic action of hexenal and of α-tocopherol concentrations in the blood serum are found to be in reciprocal relationship. Experimental hepatosis induced by intragastric administration of CCl₄ is attended by alteration of the time organization of the antitoxic function of the liver and of the concentrations of iron, α-tocopherol, and lipid peroxidation products in the blood collected from the hepatic and portal veins. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 119, N ^o 5, pp. 540–543, May, 1995 Presented by E. D. Gol'dberg, Member of the Russian Academy of Medical Sciences     

Effects of muscarine agonists and antagonists on vasopressin-stimulated water transport in the amphibian bladder

The effects of M₁ and M₂ cholinoceptors on stimulated water transport in the urinary bladder of the common frogRana temporaria L. are described. In the presence of pirenzepine, a selective M₁ cholinoceptor antagonist, carbachol stimulated water transport. Activation of M₂ cholinoceptors by oxotremorine in concentrations of 0.5–5.0 μM inhibited water transport, whereas their activation by this compound in higher concentrations (10–100 μM) stimulated it. The use of the phospholipase C inhibitor neomycin (0.5 mM) and the calmodulin inhibitor W-7 (1 mM) indicated that activation of M₂ cholinoceptors switches on phospholipid-Ca²⁺-calmodulin-dependent mechanisms. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N ^o 9, pp. 252–254, September, 1995 (Presented by P. V. Sergeev, Member of the Russian Academy of Medical Sciences)     

Effect of amiridine and tacrine on the functional degeneration of the isolated neuron

Amiridine and tacrine are found to have a concentration-dependent effect on the spontaneous activity of an isolated neuron from crawfish. Amiridine in a concentration of 1 μM reliably prolongs the lifetime of the neuron, whereas lower concentrations are inactive and a high concentration (10 μM) reduces spontaneous activity. Tacrine is unable to prolong the lifetime of the neuron. It is suggested that, unlike tacrine, the therapeutic effect of amiridine stems from its ability to prolong neuronal functioning. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 1, pp. 52–54, January, 1996 Presented by Yu. A. Romanov, Member of the Russian Academy of Medical Sciences     

The calcium channel antagonist diltiazem effectively blocks two types of potassium channels in the neuronal membranes

Effect of the Ca²⁺-channel antagonist diltiazem on potential-operated Ca²⁺ and K⁺ currents was studied on isolated edible snail neurons by a two-microelectrode patch-clamp technique. Diltiazem in a concentration of 0.1 mM inhibits Ca²⁺ current, high-threshold Ca²⁺-dependent K⁺ current, and Ca²⁺-independent K⁺ current and has no effect on low-threshold K⁺ current and leakage current. It is suggested that therapeutic effect of diltiazem is mediated through blockade of Ca²⁺ and K⁺ channels. Tranlated fromByulleten' Eksperimental'noi biologii i Meditsiny, Vol. 124, No. 9, pp. 271–274. September, 1997     

A study of the mechanism of action of befol on Ca2+ metabolism in cardiomyocytes using a FURA-2 fluorescent probe

The dynamics of the Ca-response of cardiomyocytes is studied and the efficiency of befol, verapamil, and amiodarone is compared using various experimental models of stimulation of [Ca²⁺]_i. Befol (1–5 μM) is shown to inhibit the caffeine-and strophanthin G-induced rise of [Ca²⁺]_i. Unlike verapamil and amiodarone, befol exhibits no Ca-blocking activity in modeled K-depolarization. It is concluded that the cardiotropic effect of befol is mediated through its primary action on Na⁺/Ca²⁺ exchange in cardiomyocytes, while the cardioplegic effect of verapamil and amiodarone is due to their ability to block the slow Ca²⁺ inward current. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 3, pp. 288–291, March, 1996     

Effect of ethanol concentration on the maximal specific growth rate and biomass composition ofYarrowia lipolytica mutant strain No. 1

the effect of ethanol concentration on the maximal specific growth rate and biomass composition ofYarrowia lipolytica No. 1 was studied during culturing in the pH-auxostat mode. Growth inhibition set in starting from a 2.64 g/liter residual concentration of ethanol. The constant of ethanol inhibition was 11.0 g/liter. Growth inhibition with ethanol was associated with changes of the fatty-acid composition of lipids and a resultant reduction of lipid unsaturation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 1, pp. 71–73, January, 1996 Presented by Yu. A. Romanov, Member of the Russian Academy of Medical Sciences