Effect of palmitic and lauric acids on the phospholipid bilayer membrane conductivity.

Palmitic acid increased the conductivity of BLM from mitochondrial phospholipids when they were dissolved in a mixture of decane and chlorodecane, and was ineffective when phospholipids were dissolved in decane. Lauric acid produced an increase in the membrane conductivity independently of the phospholipid type in the membrane-forming solutions (mitochondrial phospholipids, asolectin, lecithin with cholesterol) and their solvents (decane or decane with chlorodecane). The results show that discrepancies between published data concerning fatty acid effects on the BLM conductivity may be explained by differences in phospholipids, their solvents and fatty acid used.

The uncoupling effect of some psychotropic drugs on oxidative phosphorylation in rat liver mitochondria.

In the present study an attempt to detect influence of some psychotropic drugs on oxidative phosphorylation has been made. Relanium and melipramine were used in the experiments. They are among tranquilizer and antidepressant drug groups respectively. It was shown that both drugs increased the rate of oxygen consumption and displayed uncoupling properties. Mitochondrial respiration raised up slowly after drug addition in the presence of succinate or beta-oxybutyrate as oxidized substrates. If concentration of relanium and melipramine exceeded 1.2 and 0.8 mM respectively the rate of oxygen consumption began to decrease. There was a small reply on addition of ADP in the presence of drugs. At the same time relanium and melipramine decreased respiration rate if they were added at the state 3. It was shown that the drugs increased conductivity of bimolecular phospholipid membranes.

The ATP/ADP-antiporter is involved in the uncoupling effect of fatty acids on mitochondria.

The ATP/ADP-antiporter inhibitors and the substrate ADP suppress the uncoupling effect induced by low (10-20 microM) concentrations of palmitate in mitochondria from skeletal muscle and liver. The inhibitors and ADP are found to (a) inhibit the palmitate-stimulated respiration in the controlled state and (b) increase the membrane potential lowered by palmitate. The degree of efficiency decreases in the order: carboxyatractylate (CAtr) greater than ADP greater than bongkrekic acid, atractylate. GDP is ineffective, Mg.ADP is of much smaller effect, whereas ATP is effective at much higher concentration than is ADP. Inhibitor concentrations, which maximally suppress the palmitate-stimulated respiration, correspond to those needed for arresting the state 3 respiration. The extent of the CAtr-sensitive stimulation of respiration by palmitate has been found to decrease with an increase in palmitate concentration. Stimulation of the controlled respiration by p-trifluoromethoxycarbonylcyanide phenylhydrozone (FCCP) and gramicidin D at any concentrations of these uncouplers is CAtr-insensitive, whereas that caused by a low concentrations of 2,4-dinitrophenol and dodecyl sulfate is inhibited by CAtr. The above effect of palmitate develops immediately after addition of the fatty acid. It is resistant to EGTA as well as to inhibitors of phospholipase (nupercain) and of lipid peroxidation (ionol). Moreover, palmitate accelerates spontaneous release of the respiratory control, developing in rat liver mitochondria under certain conditions. This effect takes several minutes, being sensitive to EGTA, nupercain and ionol. Like the fast uncoupling, this slow effect is inhibited by ADP but CAtr and atractylate are stimulatory rather than inhibitory. In artificial planar phospholipid membrane, palmitate does not increase the membrane conductance, FCCP increases it strongly and dinitrophenol only slightly. In cytochrome oxidase proteoliposomes, FCCP, gramicidin and dinitrophenol (less effectively) lower, whereas palmitate enhances the cytochrome-oxidase-generated membrane potential. In this system, monensin substitutes for palmitate. It is concluded that the ATP/ADP antiporter is somehow involved in the uncoupling effect caused by low concentrations of palmitate and, partially, of dinitrophenol, whereas uncoupling produced by FCCP and gramicidin is due to their action on the phospholipid part of the mitochondrial membrane. A possible mechanism of this effect is discussed.

Unusual biochemistry of changes in neuron membrane permeability evoked by cAMP.

Influence of different metabolic poisons on cAMP-evoked neuron membrane permeability is investigated. Drugs preventing cAMP binding with R subunits of protein kinase decrease the cAMP-evoked current, but the inhibitor of the C subunit. H8, has no effect. The cAMP-dependent current is increased by uncouplers and decreased by inhibitors of glycolysis and oxidative phosphorylation. The mechanism of cAMP action on neuron permeability is discussed.

[Relation between respiration and swelling of liver mitochondria induced by anthracycline antibiotics]. / Sootnoshenie dykhaniia i nabukhaniia mitokhondrii pecheni, indutsiruemykh antratsiklinovymi antibiotikami.

The anthracycline antibiotics rubomycin (daunorubicin) and carminomycin at concentrations which stimulate mitochondrial respiration in the absence of ADP induce the swelling of rat liver mitochondria. Under these conditions, the lipid peroxidation (LPO) inhibitor ionol slows down both the respiration and swelling of mitochondria. This suggests that stimulation of respiration and swelling under effects of the antibiotics largely depend on LPO. In the presence of the respiration inhibitor antimycin no effect of ionol is observed. Adriamycin (doxorubicin) stimulates mitochondrial respiration in a lesser degree than rubomycin and carminomycin and fails to induce mitochondrial swelling.

Hexaammineruthenium as an electron donor to mitochondrial cytochrome oxidase: membrane potential generation in the absence of cytochrome c.

Cytochrome c oxidase can generate membrane potential in the absence of cytochrome c (e.g., in cytochrome c-deficient mitochondria or in proteoliposomes) with hexaammineruthenium as an artificial electron donor. Of several other redox mediators tested, phenazine methosulfate was found to be an efficient artificial substrate for membrane energization by cytochrome oxidase, whereas TMPD, DAD, DCPIP or ferrocyanide are virtually ineffective. The ability of Ru(NH3)6(2+) and phenazine methosulfate to support the generation of delta psi by cytochrome c-oxidase correlates with their effectiveness as electron donors to cytochrome a in the cyanide-inhibited membrane-bound enzyme.

[Effect of phosphodiesterase inhibitors on the membrane potential and respiration of mitochondria]. / Vliianie ingibitorov fosfodisterazy na membrannyi potentsial i dykhanie mitokhondrii.

Effect of papaverine, 3-isobutyl-1-methylxanthine and SQ-20009 was studied. It was shown that papaverine (50 microM) had rotenone--like action on isolated rat liver mitochondria decreasing their membrane potential and blocking respiration upon beta-oxybutyrate oxidation. Papaverine did not practically influence the membrane potential and oxygen consumption upon succinate oxidation. SQ-20009 effect was much less than that of papaverine. 3-isobutyl-1-methylxanthine (50-200 microM) was uneffective at all.

[Phosphorylation of creatine and the membrane potential of heart mitochondria]. / Fosforilirovanie kreatina i membrannyi potentsial mitokhondrii serdtsa.

The method of penetrating ions was used to measure the membrane potential and to study the creatine phosphokinase reaction in rat heart mitochondria. The concentration of adenine nucleotides in the intermembrane space at different levels of the membrane potential was estimated. The role of the diffusional layer adjacent to the inner membrane of heart mitochondria for coupling of the creatine phosphokinase reaction with oxidative phosphorylation is discussed.

[Effect of creatine phosphate synthesis on the membrane potential of mitochondria]. / Vliianie sinteza kreatinfosfata na membrannyi potentsial mitokhondrii.

The method of the penetrating ions allows to observe the creatine phosphokinase function of heart mitochondria in steady state conditions. The addition of ADP to respiring mitochondria decreases the membrane potential in the course of the ATP synthesis. The subsequent addition of creatine decreases the membrane potential for a long period of time because of ADP formation in creatine phosphokinase reaction. It was shown in the experiments with maintainance of the constant concentration of ADP or ATP in the medium that the ADP concentration in the medium acts mainly on the membrane potential during the creatine phosphate synthesis. There is no effect of creatine on the membrane potential of liver mitochondria which have no creatine phosphokinase.

[Potential difference across the membrane of subcellular particles. V. Generation of potential differences by mitochondria and submitochondrial particles under anaerobic conditions]. / Raznost' potentsialov na membrane subkletochnykh chastitis. V. Generatsiia raznosti potentsialov mitokhondriiami i submitokhondrial'nymi chastitsami v anaerobnykh usloviiakh.

It is shown by the mehtod of penetrating ions that Site O and I of the respiratory chain of submitochondrial particles are able to generate a membrane potential of the normal value under anaerobic conditons. When succinate is an electron donor and ferricyanide-an acceptor (Site II), the oxygen addition sharply increases the membrane potential at pH above 7.5 and does not change or even decreases it in reaction conditions more acid than pH 6.5. The generation of the membrane potential at low pH and in the absence of oxygen is predicted by the chemielectric hypothesis and cannot be explained by the chemiosmotic one. Mitochondria usually generate the membrane potential without O2 at pH 7.5 in the presence of ferricyanide when the substrate concentration exceeds 5 mM.

[Potential difference across the membrane of subcellular particles. IV. Study of the part of the respiratory chain from FAD to cytochrome c by the ion penetration technic]. / Raznost' potentsialov na membrane subkletochnykh chastits. IV. Izuchenie dykhatel'noi tsepi na uchastke ot FAD do tsitokhroma c metodom pronikaiushchikh ionov

Ability of mitochondria and submitochondrial particles (SMP) to generate a membrane potential on the addition of unpenetrating electron donors and acceptors and trimethylhydroquinone was used for specification of organization of the electron transfer chain. Ferri- and ferrocyanide added to mitochondria induce the membrane potential generation exchanging electrons only with cytochromes c or c1. Ferricyanide added to SMP induces the membrane potential taking electrons in three places: from NAD-H dehydrogenase, succinate dehydrogenase and in the presence of antimicyne A from cytochrome beta region. The difference of two sides of mitochondrial membrane is in agreement with the chemielectric hypothesis. According to this hypothesis protons from internal part of mitochondria are taken up to input H+-channel after electrons. That is why electrons come near the inner surface of the membrane and can be transferred from respiratory chain to water soluble acceptors. In output channels protons move under the action of intramembrane electrostatic field and in the direction of rising polarization of the medium. Protons are released to output channels while electrons are transferred to next carrier within the hydrophobic part of the membrane far from external surface of the membrane and cannot be transferred to water soluble acceptors.

[Potential difference across subcellular particle membranes. II. Compensation method of measurement]. / Raznost' potentsialov na membrane subkletochnykh chastits. II. Kompensatsionnyi metod izmerniia

"Zero-loop" of the molecular potential transformer of submitochondrial particles (SMP) is separated from the remaining electron transfer chain by rotenone, and its e.m.f. ET=0,003+RT/2F in [NADP X H] [NAD+]/[NADP+] [NAD X H] volts is used in the compensative method of measurement of the potential difference across the SMP membrane (delta USMP). The phospholipid membrane, measuring the concentration of the penetrating anions in the solution contained SMP, is used as "zero-indicators". This concentration drops monotonically with increase in delta USMP. Delta USMP is equal to ET when the addition of substrates of transhydrogenase reaction with definite ET does not change the potential across phospholipid membrane.

[Potential difference across subcellular particle membranes. I. Chemiosmotic and chemielectric mechanism of generation]. / Raznost' potentsialov na membrane subkletochnykh chastits. I. Khemiosmoticheskii i khemiélektricheskii mekhanizm generatsii

Transformation of light energy, of substrate oxidation and ATP hydrolysis energy into electric form during both oxidative and photo-phosphorylation can be described not only by means of chemiosmotic but also by chemielectric hypothesis. The latter hypothesis supposes, that dehydrated protons are taken up by electrostatic forces into the inner part of the membrane. Protons move into the input channels following electrons driven by chemical forces. Inside the membrane H+-ions are released into the output channels when electrons are transferred to the next electron carriers. Output H+-channels eject protons towards the other side of the membrane along the gradient of rising polarization of the channels. The inner resistance of chemielectric potential generators is lower than that of chemiosmotic one. A model of chemielectric mechanism is proposed. According to this mechanism electrons driving protons move along nonheme iron proteins and H+-ions are released into the output channels from semiquinones and hydroquinones.