ABSTRACT
Inotropic effects of yttrium acetate (Y³âº) on contractions of myocardium preparations of the frog Ra- na ridibunda as well as on respiration and the inner membrane potential (Δψmito) of isolated rat heart mi- tochondria were studied. It was found that 2 mM yttrium in Ringer solution significantly reduced the am- plitude of myocardium contractions evoked by electric stimulation and increased the half-relaxation time (n = 5). In experiments with Ca²âº, Y³âº decreased Ca²âº-dependent oxygen consumption rate of rat heart mitochondria, energized by glutamate and malate, impeded the reduction in respiration of these mito- chondria in state 3 or uncoupled by 2,4-dinitrophenol, and inhibited Ca²âº-induced decrease in their inner membrane potential. These data are important to better understand the mechanisms of Y³âº effects on myocardial calcium-dependent processes. Possible mechanisms of negative inotropic effect of Y³âº on the myocardium and its influence on the Ca²âº-dependent processes in rat mitochondria are discussed.
Subject(s)
Calcium/metabolism , Membrane Potential, Mitochondrial/drug effects , Mitochondria, Heart/metabolism , Myocardium/metabolism , Myocytes, Cardiac/metabolism , Oxygen Consumption/drug effects , Yttrium/pharmacology , Animals , Male , Myocardium/cytology , Myocytes, Cardiac/cytology , Rana ridibunda , Rats , Rats, WistarABSTRACT
Ganglioside GM1 has been shown to increase viability of PC12 cells at their induction of oxidative stress by hydrogen peroxide. However, in the presence of inhibitor of tyroxine kinase Trk-receptors K-252a this GM1 effect decreases or virtually disappears. To understand mechanism of the protective effect, there was studied action of H2O2, GM1, and inhibitor K-252a on formation of reactive oxygen species (ROS). It has been shown that ganglioside GM1 decreases significantly the H2O2-induced ROS accumulation in PC12 cells; however, in the presence of inhibitory of tyrosine kinase of Trk-receptors, this GM1 effect is not revealed. It has been found that inhibitors of each of protein kinases present at the signal realization stages following the stages of activation of tyrosine kinase Trk-receptors--Erk 1/2, PI3-kinases, and PKC, decreased the GM1 ability to reduce the H2O2-induced ROS accumulation, while in the combined use of inhibitors of these three protein kinases, the GM1 effect was completely absent. Thus, the ganglioside GM1 antioxidant effect on PC12 is mediated by activation of tyrosine kinase Trk-receptors and protein kinases perceiving signal from this enzyme.
Subject(s)
Antioxidants/pharmacology , G(M1) Ganglioside/pharmacology , Oxidative Stress/drug effects , Receptor Protein-Tyrosine Kinases/metabolism , Signal Transduction/drug effects , Animals , Carbazoles/pharmacology , Cell Survival/drug effects , Enzyme Inhibitors/pharmacology , Hydrogen Peroxide/metabolism , Hydrogen Peroxide/pharmacology , Indole Alkaloids/pharmacology , Mitogen-Activated Protein Kinase 3/metabolism , Oxidants/metabolism , Oxidants/pharmacology , PC12 Cells , Phosphatidylinositol 3-Kinases/metabolism , Protein Kinase C/metabolism , Rats , Receptor Protein-Tyrosine Kinases/antagonists & inhibitorsABSTRACT
Data in the fatty acid composition of muscle tissue phospholipids of some representatives of gastropod molluscs (Gastropoda) have been presented for the first time. In the lake phytophagues Lymnaea stagnalis and Lymnaea ovata the long-chained C22-acid was not detected, whereas in the predator common whelk Buccinum undatum, C22:6omega3 was present. Comparison of absorption spectra (240-720 nm) of lipid extracts of the studied invertebrates and of rat has been performed. The obtained data are discussed from the point of view of participation of pi-electrons of phospholipid fatty acid molecules in adaptation of membranes to the habitation temperature, which arises owing to interelectron attraction and to the process of formation of Cooper's pairs.
Subject(s)
Adaptation, Physiological , Electrons , Fatty Acids/metabolism , Lymnaea/physiology , Mytilus/physiology , Phospholipids/metabolism , Temperature , Animals , Cell Membrane/drug effects , Cell Membrane/metabolism , Chromatography, Thin Layer , Fatty Acids/chemistry , Lipid Metabolism/physiology , Lymnaea/growth & development , Lymnaea/metabolism , Muscles/metabolism , Muscles/physiology , Mytilus/growth & development , Mytilus/metabolism , Phospholipids/chemistry , Rats , Species SpecificityABSTRACT
Effects of inhibitors of tyrosine kinases (K-252a, genistein) and of phospholipase A2 (bromophenacetyl bromide) on viability of PC12 cells are studied in the presence of hydrogen peroxide and ganglioside GM1. The degree of inhibition of hydrogen peroxide cytotoxic effect by ganglioside GM1 amounted to 52.8 +/- 4.3 %. However, in the presence in the medium of 0.1 and 1 microM inhibitors of tyrosine kinase of Trk-receptors (K-252a) it was as low as 32.7 +/- 6.5 % and 11.7 +/- 9.8 %, respectively. GM1 prevented Na+, K+-ATPase produced by H2O2, but in the presence of 1 microM K-252a this effect was practically not pronounced. In the presence of another inhibitor of tyrosine kinases--genistein, a tendency for a decrease of the GM1 protective effect was observed at its concentrations 0.1 and 1 microM, whereas at a higher concentration 10 microM genistein depressed the GM1 neuroprotective effect statistically significantly. It was found that inhibitor of phospholipase A2 bromophenacetyl bromide did not affect the action of GM1 aimed at increasing the viability of cells under action of hydrogen peroxide on them. It seems that this enzyme is not involved in the cascade of reactions participating in realization of the ganglioside protective effect. Thus, inhibitor of tyrosine kinase of Trk-receptors K-252 decreases or practically prevents the ganglioside GM1 neuroprotective effect of PC12 cells under stress conditions; the same ability is characteristic of genistein--an inhibitor of tyrosine kinases of the wider spectrum of action.
Subject(s)
G(M1) Ganglioside/pharmacology , Neuroprotective Agents/pharmacology , Oxidative Stress/drug effects , Receptor Protein-Tyrosine Kinases/metabolism , Animals , Enzyme Inhibitors/pharmacology , Hydrogen Peroxide/pharmacology , Oxidants/pharmacology , PC12 Cells , Phospholipase A2 Inhibitors , Rats , Receptor Protein-Tyrosine Kinases/antagonists & inhibitorsABSTRACT
Used in this work are PC12 cells transfected with human gene expressing amyloid precursor protein of beta-peptide and carrying the so-called "Swedish mutation" leading to the appearance of one Alzheimer's disease family forms. It has been shown that the PC12 cells transfected with this mutant gene, at action of various hydrogen peroxide concentrations, die to the significant greater degree than the used for comparison PC12 cells transfected with analogous human gene of the wild type or than vector-transfected cells. It has been found that ganglioside GM1 at micro- or nanomolar concentrations is able to increase viability of the PC12 cells transfected with the mutant gene causing a significant accumulation of endogenous amyloid beta-peptide. The obtained data confirm an important role of oxidative stress in injury and death of brain nerve cells in Alzheimer's disease.
Subject(s)
Alzheimer Disease/metabolism , Amyloid beta-Peptides/biosynthesis , Hydrogen Peroxide/pharmacology , Mutation , Oxidants/pharmacology , Oxidative Stress/drug effects , Alzheimer Disease/genetics , Amyloid beta-Peptides/genetics , Animals , Cell Death/drug effects , Cell Death/genetics , Dose-Response Relationship, Drug , G(M1) Ganglioside/metabolism , Humans , Oxidative Stress/genetics , PC12 Cells , Rats , TransfectionABSTRACT
To elucidate mechanism of ganglioside neuroprotection, it is important to study their metabolic effects, specifically of action on Na+, K+ -ATPase. It has been shown that under effect of oxidative stress inductors and neurotoxins an oxidative inactivation of this enzyme takes place in PC12 cells and brain cortex synaptosomes, this inactivation being able to be prevented or decreased by ganglioside GM1. Thus, for instance, 24 h after action of 1 mM H2O2, activity of Na+, K+ -ATPase in PC12 cells decreased more than twice. However, in the case of preincubation of the cells with ganglioside GM1 prior to the H2O2 action this enzyme activity did not differ statistically significantly from control. Ganglioside GM1 also was able to increase significantly the enzyme activity decreased by action on the PC12 cells of amyloid beta-peptide (AP) causing lesion of neurons in Alzheimer's disease and at low H202 concentrations. Experiments on brain cortex synaptosomes have established that not only antioxidants--alpha-tocopherol and superoxide dismutase--but also ganglioside GM1 prevent the glutamateproduced Na+, K+ -ATPase oxidative inactivation. The obtained data agree with a suggestion that the ganglioside neuroprotective effect at action on nerve cells of such toxins as Abeta, glutamate or reactive oxygen species is due to their ability to inhibit the free-radical reactions.
Subject(s)
G(M1) Ganglioside/pharmacology , Neuroprotective Agents/pharmacology , Neurotoxins/pharmacology , Oxidative Stress/drug effects , Sodium-Potassium-Exchanging ATPase/metabolism , Synaptosomes/drug effects , Amyloid beta-Peptides/pharmacology , Animals , Antioxidants/pharmacology , Cerebral Cortex/metabolism , Cerebral Cortex/ultrastructure , Enzyme Activation , Glutamic Acid/pharmacology , Hydrogen Peroxide/pharmacology , Male , PC12 Cells , Peptide Fragments/pharmacology , Rats , Rats, Wistar , Sodium-Potassium-Exchanging ATPase/antagonists & inhibitors , Superoxide Dismutase/pharmacology , Synaptosomes/metabolism , alpha-Tocopherol/pharmacologySubject(s)
Gangliosides/pharmacology , Neurons/drug effects , Neuroprotective Agents/pharmacology , Oxidative Stress/drug effects , Animals , Ascorbic Acid/toxicity , Cell Survival/drug effects , Cells, Cultured , Cerebellum/cytology , Culture Media, Serum-Free , Ferrous Compounds/toxicity , Glutamic Acid/toxicity , Hydrogen Peroxide/toxicity , L-Lactate Dehydrogenase/metabolism , Neurons/physiology , PC12 Cells , Rats , Rats, WistarSubject(s)
Cerebral Cortex/enzymology , Glutamic Acid/physiology , Sodium-Potassium-Exchanging ATPase/antagonists & inhibitors , Superoxide Dismutase/metabolism , Synaptosomes/enzymology , Vitamin E/metabolism , Animals , Calcium/metabolism , Cerebral Cortex/drug effects , Cerebral Cortex/ultrastructure , Glutamic Acid/pharmacology , In Vitro Techniques , Lipid Peroxidation/drug effects , Rats , Rats, Wistar , Sulfhydryl Compounds/metabolism , Superoxide Dismutase/pharmacology , Synaptosomes/drug effects , Vitamin E/pharmacologySubject(s)
Adaptation, Physiological/physiology , Fatty Acids, Unsaturated/metabolism , Fatty Acids/metabolism , Lipid Bilayers/metabolism , Regeneration/physiology , Rod Cell Outer Segment/metabolism , Adaptation, Physiological/radiation effects , Animals , Cattle , Chromatography, Gas , Fatty Acids/analysis , Fatty Acids/radiation effects , Fatty Acids, Unsaturated/analysis , Fatty Acids, Unsaturated/radiation effects , In Vitro Techniques , Light , Lipid Bilayers/analysis , Lipid Bilayers/radiation effects , Male , Regeneration/radiation effects , Rod Cell Outer Segment/chemistry , Rod Cell Outer Segment/radiation effectsABSTRACT
The participation of unsaturated (linoleic and arachidonic) and saturated (palmitic) fatty acids in reacylation of phosphatidylethanolamine (PE) in synaptosomes, photoreceptor membranes and erythrocytes at oxidative stress was studied. Induction of lipid peroxidation (LPO) was found to result in a significant decrease in the content of PE polyenoic fatty acids due to their oxidative destruction. It might be related to both an activation of phospholipase A2 and a decrease in PE reacylation rate. On contrary, under the same conditions an increase in incorporation of palmitic acid into PE was observed. The results of this study suggest that phospholipid deacylation-reacylation reactions comprise an important mechanism of both protection and adaptation of organisms to oxidative stress.
Subject(s)
Erythrocyte Membrane/metabolism , Lipid Bilayers/metabolism , Membrane Lipids/metabolism , Oxidative Stress/physiology , Phosphatidylethanolamines/metabolism , Photoreceptor Cells/metabolism , Synaptosomes/metabolism , Acylation , Animals , Brain/metabolism , Cattle , Fatty Acids/metabolism , Humans , Lipid Peroxidation , Male , RatsSubject(s)
2',3'-Cyclic-Nucleotide Phosphodiesterases/antagonists & inhibitors , Guanosine Triphosphate/pharmacology , Phosphodiesterase Inhibitors , Photoreceptor Cells/enzymology , Rod Cell Outer Segment/enzymology , 2',3'-Cyclic-Nucleotide Phosphodiesterases/isolation & purification , Animals , Cattle , Enzyme Activation , Phosphoric Diester HydrolasesABSTRACT
A new set of am and ts-mutants of the phage phi80 was isolated. A series of lambdacI857h80att80int3 prophage deletion strains, extending for various lengths into the region of structural genes was generated and characterized in order to facilitate the mapping of the phi80 am and ts-mutants. Complementation test allowed to find out 5 new genes named 20, 21, 22, 23 and 24. The result of the deletion mapping of structural genes is as follows: 1-2-3-20-4-5-6-21-7-22-9-23-10-8-12-24-13.