[The M-receptor stimulation of phosphatidylinositol metabolism in the isolated rabbit heart]. / M-retseptornaia stimuliatsiia obmena fosfatidilinozitidov v izolirovannom serdtse krolika.

The activating effect of a M-receptor agonist carbachol on phosphatidylinositol metabolism under perfusion of the isolated rabbit heart with 32Pi was shown. An increase of the inclusion of 32P in phosphatidylinositol-4-phosphate and phosphatidylinositol-4-diphosphate was found. Simultaneously there was detected an elevation of the levels of products of hydrolysis of inositol phospholipids--inositol-1,4-diphosphate and inositol-1,4,5-triphosphate. There was noted the blocking action of carbachol on the contractile activity of the heart that manifested itself in a lowering of the systolic pressure in the left ventricle and a slowing of the contraction rate.

[Phosphorylation of myocardial sarcolemma proteins during induction of the phosphatidylinositol cycle in isolated perfused rabbit heart]. / Fosforilirovanie belkov sarkolemmy miokarda pri induktsii fosfatidilinozitidnogo tsikla v izolirovannom perfuziruemom serdtse krolika.

Phosphorylation of cardiac sarcolemma proteins under stimulation of M-receptors by agonist carbacholine used to stimulate phosphatidylinositide cycle, was investigated in the isolated, rabbit heart perfused with 32Pi. Carbacholine (10(-7) stimulates the polyphosphoinositide metabolism which is expressed in the activated incorporation of 32P from [gamma-32P]ATP in polyphosphoinositide as well as in the increased content of the labelled inositol trisphosphate released through phosphatidylinositol-4,5-bisphosphate break-down by phospholipase C. The diacylglycerol produced simultaneously with inositol triphosphate as a second messenger activates the protein kinase C. This was confirmed by considerable activation of phosphorylation sarcolemma proteins-substrates of protein kinase C, with Mr 94, 87, 78, 51 and 46 kDa.

[Ca2+-phospholipid-dependent phosphorylation of vesicular preparations of myocardial sarcolemma]. / Ca2+-fosfolipidzavisimoe fosforilirovanie vezikulirovannykh preparatov sarkolemmy miokarda.

A Ca2+-phospholipid-dependent protein kinase C was isolated from the soluble fraction of bovine brain, using hydrophobic chromatography on phenyl-Sepharose CL-4B and high performance liquid chromatography on a Mono Q column. The enzyme had a specific activity of 822 nmol 32P/mg protein/min with histone H1 as a substrate. Phosphorylation of pig myocardium sarcolemma protein substrates was stimulated by Ca2+ and phosphatidylserine; the optimal concentrations of these compounds were 10(-4) M and 200 micrograms/ml, respectively. The value of Km(app) for Ca2+ was 3.10(-6) M. An addition of exogenous dioleine increased the enzyme affinity for Ca2+ which led to a decrease of Ca2+ concentration necessary for the maximal activation to occur. The optimal concentration of ATP needed for sarcolemmal preparation phosphorylation was 0.3-0.4 mM, which seems to be due to the high activity of sarcolemmal ATPases. The proteins phosphorylated in sarcolemmal preparations were identified, using SDS polyacrylamide gel electrophoresis with subsequent autoradiography. The 250, 140, 67, 58, 25 and 11 kD proteins appeared to be phosphorylated in the greatest degree. Since in myocardial sarcolemma protein kinase C predominantly phosphorylates the same proteins as does the cAMP-dependent protein kinase, it was assumed that protein kinase C can also play a role in the regulation of Ca2+-transporting systems of sarcolemma.

[ATP-dependent transport of Ca2+ in myocardium sarcolemma vesicles and its activation by phorbol esters]. / ATP-zavisimyi transport Ca2+ vezikulirovannymi preparatami sarkolemmymiokarda i ego aktivatsiia forbolovymi éfirami.

Highly purified pig myocardium sarcolemma vesicles possess the Ca2+,Mg2+-ATPase activity (4.1 mumol Pi/mg protein/hour) and induce the ATP-dependent accumulation of 45Ca2+ (6.0 nmol/mg protein/min). This reaction is not stimulated by oxalate; Ca2+ are released from the vesicles by saponin and Na+ treatment, which suggests that Ca2+ transport against the concentration gradient is induced by myocardium sarcolemma vesicles and not by sarcoplasmic reticulum fragments. The phorbol ester possessing a biological activity of a growth-promoting factor and activating membrane-bound protein kinase C stimulates the Ca2+,Mg2+-ATPase activity and the ATP-dependent accumulation of Ca2+, whereas its counterpart devoid of biological activity does not influence Ca2+ transport. Polymixin B, a specific inhibitor of protein kinase C, prevents the activating effect of phorbol esters on Ca2+ accumulation inside the vesicles. It is suggested that the ATP-dependent transport of Ca2+ in myocardium sarcolemma is controlled by Ca2+-phospholipid-dependent phosphorylation catalyzed by protein kinase C.

[Relation between the passive transport of calcium into vesicles of the myocardial sarcolemma and membrane potential]. / Zavisimost' passivnogo transporta kal'tsiia v vezikuly sarkolemmy miokarda ot membrannogo potentsiala.

The effect of membrane potential on the passive 45Ca2+ uptake by cardial sarcolemmal vesicles was investigated. Membrane potentials were generated by the K+ gradient in the presence of valinomycin and were measured using fluorescent dye diS-C3-(5). It was shown that the 45Ca2+ influx into vesicles increased twice after membrane depolarization. Evaluation of the 45Ca2+ influx over a wide range of membrane potentials produced a profile similar to that of current-voltage relationships for single calcium channels in isolated cardiomyocytes. Passive 45Ca2+ transport was inhibited by 1 mM Cd2+ and Co2+. It is suggested that the voltage-dependent Ca2+ influx into vesicles occurs through Ca2+-channels.

[Effect of phospholipases A2 from bee and cobra venom on the phospholipid composition and Na+-,K+-ATPase activity of synaptosomes]. / Vliianie fosfolipaz A2 iada pvely i kobry na fosfolipidnyi sostav i Na+-K+-ATPaznuiu aktivnost' sinaptosom.

The bee and cobra venom phospholipases A2 as well as partially acetylated cobra venom phospholipase A2 are studied for their effect on phospholipid composition of synaptosomes and their Mg2+- and Na+,K+-ATPase activity. It is established that these phospholipases induce the splitting of phosphatidylethanolamine, phosphatidylcholine and phosphatidylserine, inhibition of the Na+,K+-ATPase activity and activation of Mg2+-ATPase. Bee venom phospholipase A2 is more effective than cobra venom phospholipase A2, the both phospholipases splitting phosphatidylethanolamine most intensively. The ATPase activity may be partially or completely restored by exogenic phosphatidylcholine and phosphatidylserine; exogenic phosphatidylethanolamine is not efficient in this respect.

[Role of choline uptake by nerve endings in synaptic transmission]. / Rol' zakhvata kholina nervnymi okonchaniiami v sinapticheskoi peredache.

The paper deals with modern ideas concerning the sources of free choline in the brain, mechanisms of its transport to nerve endings and utilization for synthesis of acetylcholine.

[Release of 14C-acetylcholine from synaptosomes as affected by presynaptic neurotoxins from bee and cobra venoms--phospholipases A2]. / Vysvobozhdenie [14C] atsetilkholina iz sinaptosom pod vliianiem presinapticheskikh neirotoksinov iz iadov zmei i pchely--fosfolipaz A2.

The effect of presynaptic neurotoxin from bee and cobra venom--phospholipases A2 on Na+-dependent high affinity [14C]choline transport from the striate body of rat brain into synaptosomes has been studied. It was shown that both phospholipases A2 inhibit the re-uptake of [14C]choline and specifically stimulate the release of [14C]acetylcholine from the synaptosomes. This effect is especially well-pronounced for bee venom phospholipase A2. It was assumed that damages of biochemical processes on the presynaptic membrane result in a blockade of synaptic transmission in nerve-muscle preparations.

[Effect of phospholipase A2 from the venoms of bee and Middle Asian cobra on choline uptake by synaptosomes]. / Vliianie fosfolipaz A2 iz iadov pchely i sredneaziatskoi kobry na zakhvat kholina sinaptosomami.

The effect of purified phospholipase A2 from venom of the bee Apis mellifica and from venom of the cobra Naja naja oxiana on the Na+-dependent high affinity choline transport into the synaptosomes of rabbit corpus striatum (active uptake) was studied. Both phospholipases A2 were shown to inhibit the active choline uptake by the synaptosomes. The bee venom phospholipase at a concentration of 10(-8) M and the cobra venom phospholipase at a concentration of 10(-6) M produced a 50% inhibition of choline uptake. A relationship was found between the enzymatic activity of the phospholipases and their ability to block choline uptake by the synaptosomes. A removal of Ca-ions from the medium abolished the effects of both phospholipases. Replacement of Ca2+ by Sr2+ inhibited the effect of the cobra venom phospholipases but did not inhibit that of bee venom enzyme.

[Simultaneous extraction and fluorimetric determination of noradrenaline, dopamine, serotonin and 5-hydroxyindoleacetic acid in separate small brain segments]. / Odnovremennaia ékstraktsiia i fliuorimetricheskoe opredelenie noradrenalina, dofamina, serotonina i 5-oksiindoluksusnoi kisloty v otdel'nykh nebol'shikh uchastkakh mozga.

Highly-sensitive and reproducible method is developed for simultaneous assay of noradrenaline, dopamine, serotonin and 5-hydroxyindolylacetic acid in small samples of brain tissue. The procedure comprised extraction of the substances with acidified butanol, reextraction of the compounds with phosphate buffer in presence of isooctane, separation of the amines form precursors and metabolites using ion exchange resin Amberlite CG-50 and of 5-hydroxyindolylacetic acid--on Sephadex G-10.

[Kinetic studies of melipramine inhibition of Na+, K+-ATPase activity in the synaptosomal fraction of the brain]. / Kinetychni doslidzhennia hal'muvannia melipraminom NA+,K+-ATF-aznoï sktyvnosti synaptosomnoï fraktsii mozku

The effect of antidepressant melipramine (imipramine) on the Na+, K+-ATPase activity was studied in the brain synaptosomes as dependent on the sodium and potassium ions concentration and pH of the incubation medium. Melipramine in concentrations of 0.05-1.0 mM is shown to inhibit the Na+, K+-ATPase activity. Under pH 7.4 monovalent cations prevent the inhibitory action of melipramine, changing the kinetic of the interaction between melipramine and the enzyme preparation. When changing pH from 7.4 to 8.2 the preventional action of the ions decreases, and the inhibitory action of melipramine on the Na+, K+-ATPase activity increases. Possible mechanisms of the melipramine interaction with Na+, K+-ATPase system are discussed.

[Neurochemical mechanisms of the action of tricyclic antidepressants of the imipramine group]. / Neirokhimicheskie mekhanizmy deistviia tritsiklicheskikh antidepressantov gruppy imipramina

The main role in determination of the pharmacologic effects of the imipramine groups antidepressants is given to their influence on neurotransmitters metabolism in synapses, the activity of enzymic systems regulating the transport of ions, as well as on the system of cyclic AMP metabolism. Interaction of tricyclic antidepressants with membrane and, as the result, distrubance in reuptake of transmitters (epinephrine and 5-hydroxytryptamine) in neurons is supposed to be one of the mechanisms of synaptic transmission regulation. The possible role in inhibition of biological amines deamination, in particular of phenylethylamine, in antidepressive effect of tricyclic antidepressants is discussed. It is supposed that the thymoanaleptic effects of the imipramine group antidepressants are due to activation of central serotoninergic processes, and their psychoanaleptic effect due to activation of the adrenergic system. Inhibition of the Na+, K+-ATPase activity quilizing effect of tricyclic antidepressants.