The Role of ATP-Sensitive Potassium Channels and Nitric Oxide in the Protective Effect of Preconditioning of the Brain

© 2017 Springer Science+Business Media, LLC, part of Springer Nature Objective. The role of ATP-dependent potassium (K + ATP ) channels in the neuroprotective effect of ischemic (IPre) and pharmacological (PPre) preconditioning and changes in blood levels of nitric oxide (NO) metabolites were studied in conditions of cerebral ischemia. Materials and methods. Ischemic stroke (IS) was modeled in male rats (n = 86) by electrocoagulation of a branch of the middle cerebral artery (MCA). The nonselective K + ATP channel blocker glibenclamide and the K + ATP channel activator diazoxide were used. IPre and PPre were performed one day before MCA occlusion. Blood concentrations of NO, nitrates (NO 3 – ) and nitrites (NO 2 – ) were determined in experimental animals at 5, 24, and 72 h after MCA occlusion. Results. IPre decreased the lesion zone by 37% (p < 0.05), while prior administration of glibenclamide countered the action of IPre. The protective effect of PPre was analogous to that of IPre. Decreases in blood levels of oxygenated R-conformers of hemoglobin-bound NO (Hb-NO) were seen 5 h after MCA occlusion, with an inversely proportional increase in the concentration of nonoxygenated T-conformers; there were also increases in NO 3 – and NO 2 – concentrations. NO 3 – and NO 2 – levels showed normalization by one day after MCA occlusion, along with changes in the concentrations of Hb-NO complexes – R-conformers dominated, while the blood level of T-conformers reached a minimum. Furthermore, by 24 h there was a correlation between blockade of K + ATP channels and decreases in serum NO 3 – and NO 2 – levels (p < 0.03). Conclusions. The neuroprotective effect of preconditioning was due to activation of K + ATP channels. Analysis of blood levels of NO metabolites in rats with IS showed that Hb-NO complexes in the R-conformation stored and carried NO to the tissues, releasing NO on occurrence of the R → T transition in ischemic conditions

Molecular bases of brain preconditioning

© 2017 Deryagin, Gavrilova, Gainutdinov, Golubeva, Andrianov, Yafarova, Buravkov and Koshelev. Preconditioning of the brain induces tolerance to the damaging effects of ischemia and prevents cell death in ischemic penumbra. The development of this phenomenon is mediated by mitochondrial adenosine triphosphate-sensitive potassium (KATP+) channels and nitric oxide signaling (NO). The aim of this study was to investigate the dynamics of molecular changes in mitochondria after ischemic preconditioning (IP) and the effect of pharmacological preconditioning (PhP) with the KATP+-channels opener diazoxide on NO levels after ischemic stroke in rats. Immunofluorescence-histochemistry and laser-confocal microscopy were applied to evaluate the cortical expression of electron transport chain enzymes, mitochondrial KATP+-channels, neuronal and inducible NO-synthases, as well as the dynamics of nitrosylation and nitration of proteins in rats during the early and delayed phases of IP. NO cerebral content was studied with electron paramagnetic resonance (EPR) spectroscopy using spin trapping. We found that 24 h after IP in rats, there is a two-fold decrease in expression of mitochondrial KATP+-channels (p = 0.012) in nervous tissue, a comparable increase in expression of cytochrome c oxidase (p = 0.008), and a decrease in intensity of protein S-nitrosylation and nitration (p = 0.0004 and p = 0.001, respectively). PhP led to a 56% reduction of free NO concentration 72 h after ischemic stroke simulation (p = 0.002). We attribute this result to the restructuring of tissue energy metabolism, namely the provision of increased catalytic sites to mitochondria and the increased elimination of NO, which prevents a decrease in cell sensitivity to oxygen during subsequent periods of severe ischemia

The Role of ATP-Sensitive Potassium Channels and Nitric Oxide in the Protective Effect of Preconditioning of the Brain

© 2017 Springer Science+Business Media, LLC, part of Springer Nature Objective. The role of ATP-dependent potassium (K + ATP ) channels in the neuroprotective effect of ischemic (IPre) and pharmacological (PPre) preconditioning and changes in blood levels of nitric oxide (NO) metabolites were studied in conditions of cerebral ischemia. Materials and methods. Ischemic stroke (IS) was modeled in male rats (n = 86) by electrocoagulation of a branch of the middle cerebral artery (MCA). The nonselective K + ATP channel blocker glibenclamide and the K + ATP channel activator diazoxide were used. IPre and PPre were performed one day before MCA occlusion. Blood concentrations of NO, nitrates (NO 3 – ) and nitrites (NO 2 – ) were determined in experimental animals at 5, 24, and 72 h after MCA occlusion. Results. IPre decreased the lesion zone by 37% (p < 0.05), while prior administration of glibenclamide countered the action of IPre. The protective effect of PPre was analogous to that of IPre. Decreases in blood levels of oxygenated R-conformers of hemoglobin-bound NO (Hb-NO) were seen 5 h after MCA occlusion, with an inversely proportional increase in the concentration of nonoxygenated T-conformers; there were also increases in NO 3 – and NO 2 – concentrations. NO 3 – and NO 2 – levels showed normalization by one day after MCA occlusion, along with changes in the concentrations of Hb-NO complexes – R-conformers dominated, while the blood level of T-conformers reached a minimum. Furthermore, by 24 h there was a correlation between blockade of K + ATP channels and decreases in serum NO 3 – and NO 2 – levels (p < 0.03). Conclusions. The neuroprotective effect of preconditioning was due to activation of K + ATP channels. Analysis of blood levels of NO metabolites in rats with IS showed that Hb-NO complexes in the R-conformation stored and carried NO to the tissues, releasing NO on occurrence of the R → T transition in ischemic conditions

The role of ATP-dependent potassium channels and nitric oxide system in the neuroprotective effect of preconditioning

© 2016, Media Sphera. All rights reserved.Objective. To study a role of ATP-dependent potassium channels (K+ATP) in the neuroprotective effect of ischemic (IP) and pharmacological (PP) preconditioning and evaluate the dynamics of blood nitric oxide (NO) metabolites in cerebral ischemia. Material and methods. A model of ischemic stroke induced by the electrocoagulation of a middle cerebral artery (MCA) branch was used in male rats (n=86). Glibenclamide, a selective inhibitor of ATP-sensitive K+ channels, and diazoxide, a potassium channel activator, were used. IP and PP were performed 24 h before MCA occlusion. Blood concentrations of NO, NO3-and NO2-were measured 5, 24 and 72 h after occlusion. Results. IP decreased a lesion area by 37% (p<0/05) and the preliminary introduction ofglibenclamide levelled the effect of IP. A protective effect of PP was similar to that of IP. A decrease in oxygenated R-conformers of Hb-NO and a reverse increase in non-oxygenated T-conformers as well as NO3-и NO2-were noted 5h after MCA occlusion. In the first 24 h after MCA occlusion, contents of NO3-and NO2-returned to normal values. There were changes in the concentrations of Hb-NO complexes as well, with the predominance of R-conformers and minimal contents of T-conformers. Moreover, the correlations between K+ATP channel blockade and the decrease in serum NO3-and NO2 were found (p<0/03). Conclusion. The neuroprotective effect of preconditioning is caused by the activation of K+ATP channels. An analysis of NO metabolite concentrations in the blood of rats with IP suggests that Hb-NO complexes belonging to R-conformers deposit and carry NO in tissues releasing NO accumulated via R→T transfer in conditions of ischemia

The role of ATP-dependent potassium channels and nitric oxide system in the neuroprotective effect of preconditioning

© 2016, Media Sphera. All rights reserved.Objective. To study a role of ATP-dependent potassium channels (K+ATP) in the neuroprotective effect of ischemic (IP) and pharmacological (PP) preconditioning and evaluate the dynamics of blood nitric oxide (NO) metabolites in cerebral ischemia. Material and methods. A model of ischemic stroke induced by the electrocoagulation of a middle cerebral artery (MCA) branch was used in male rats (n=86). Glibenclamide, a selective inhibitor of ATP-sensitive K+ channels, and diazoxide, a potassium channel activator, were used. IP and PP were performed 24 h before MCA occlusion. Blood concentrations of NO, NO3-and NO2-were measured 5, 24 and 72 h after occlusion. Results. IP decreased a lesion area by 37% (p<0/05) and the preliminary introduction ofglibenclamide levelled the effect of IP. A protective effect of PP was similar to that of IP. A decrease in oxygenated R-conformers of Hb-NO and a reverse increase in non-oxygenated T-conformers as well as NO3-и NO2-were noted 5h after MCA occlusion. In the first 24 h after MCA occlusion, contents of NO3-and NO2-returned to normal values. There were changes in the concentrations of Hb-NO complexes as well, with the predominance of R-conformers and minimal contents of T-conformers. Moreover, the correlations between K+ATP channel blockade and the decrease in serum NO3-and NO2 were found (p<0/03). Conclusion. The neuroprotective effect of preconditioning is caused by the activation of K+ATP channels. An analysis of NO metabolite concentrations in the blood of rats with IP suggests that Hb-NO complexes belonging to R-conformers deposit and carry NO in tissues releasing NO accumulated via R→T transfer in conditions of ischemia

The Role of ATP-Sensitive Potassium Channels and Nitric Oxide in the Protective Effect of Preconditioning of the Brain

© 2017 Springer Science+Business Media, LLC, part of Springer Nature Objective. The role of ATP-dependent potassium (K + ATP ) channels in the neuroprotective effect of ischemic (IPre) and pharmacological (PPre) preconditioning and changes in blood levels of nitric oxide (NO) metabolites were studied in conditions of cerebral ischemia. Materials and methods. Ischemic stroke (IS) was modeled in male rats (n = 86) by electrocoagulation of a branch of the middle cerebral artery (MCA). The nonselective K + ATP channel blocker glibenclamide and the K + ATP channel activator diazoxide were used. IPre and PPre were performed one day before MCA occlusion. Blood concentrations of NO, nitrates (NO 3 – ) and nitrites (NO 2 – ) were determined in experimental animals at 5, 24, and 72 h after MCA occlusion. Results. IPre decreased the lesion zone by 37% (p < 0.05), while prior administration of glibenclamide countered the action of IPre. The protective effect of PPre was analogous to that of IPre. Decreases in blood levels of oxygenated R-conformers of hemoglobin-bound NO (Hb-NO) were seen 5 h after MCA occlusion, with an inversely proportional increase in the concentration of nonoxygenated T-conformers; there were also increases in NO 3 – and NO 2 – concentrations. NO 3 – and NO 2 – levels showed normalization by one day after MCA occlusion, along with changes in the concentrations of Hb-NO complexes – R-conformers dominated, while the blood level of T-conformers reached a minimum. Furthermore, by 24 h there was a correlation between blockade of K + ATP channels and decreases in serum NO 3 – and NO 2 – levels (p < 0.03). Conclusions. The neuroprotective effect of preconditioning was due to activation of K + ATP channels. Analysis of blood levels of NO metabolites in rats with IS showed that Hb-NO complexes in the R-conformation stored and carried NO to the tissues, releasing NO on occurrence of the R → T transition in ischemic conditions

The Role of ATP-Sensitive Potassium Channels and Nitric Oxide in the Protective Effect of Preconditioning of the Brain

© 2017 Springer Science+Business Media, LLC, part of Springer Nature Objective. The role of ATP-dependent potassium (K + ATP ) channels in the neuroprotective effect of ischemic (IPre) and pharmacological (PPre) preconditioning and changes in blood levels of nitric oxide (NO) metabolites were studied in conditions of cerebral ischemia. Materials and methods. Ischemic stroke (IS) was modeled in male rats (n = 86) by electrocoagulation of a branch of the middle cerebral artery (MCA). The nonselective K + ATP channel blocker glibenclamide and the K + ATP channel activator diazoxide were used. IPre and PPre were performed one day before MCA occlusion. Blood concentrations of NO, nitrates (NO 3 – ) and nitrites (NO 2 – ) were determined in experimental animals at 5, 24, and 72 h after MCA occlusion. Results. IPre decreased the lesion zone by 37% (p < 0.05), while prior administration of glibenclamide countered the action of IPre. The protective effect of PPre was analogous to that of IPre. Decreases in blood levels of oxygenated R-conformers of hemoglobin-bound NO (Hb-NO) were seen 5 h after MCA occlusion, with an inversely proportional increase in the concentration of nonoxygenated T-conformers; there were also increases in NO 3 – and NO 2 – concentrations. NO 3 – and NO 2 – levels showed normalization by one day after MCA occlusion, along with changes in the concentrations of Hb-NO complexes – R-conformers dominated, while the blood level of T-conformers reached a minimum. Furthermore, by 24 h there was a correlation between blockade of K + ATP channels and decreases in serum NO 3 – and NO 2 – levels (p < 0.03). Conclusions. The neuroprotective effect of preconditioning was due to activation of K + ATP channels. Analysis of blood levels of NO metabolites in rats with IS showed that Hb-NO complexes in the R-conformation stored and carried NO to the tissues, releasing NO on occurrence of the R → T transition in ischemic conditions

The role of ATP-dependent potassium channels and nitric oxide system in the neuroprotective effect of preconditioning

© 2016, Media Sphera. All rights reserved.Objective. To study a role of ATP-dependent potassium channels (K+ATP) in the neuroprotective effect of ischemic (IP) and pharmacological (PP) preconditioning and evaluate the dynamics of blood nitric oxide (NO) metabolites in cerebral ischemia. Material and methods. A model of ischemic stroke induced by the electrocoagulation of a middle cerebral artery (MCA) branch was used in male rats (n=86). Glibenclamide, a selective inhibitor of ATP-sensitive K+ channels, and diazoxide, a potassium channel activator, were used. IP and PP were performed 24 h before MCA occlusion. Blood concentrations of NO, NO3-and NO2-were measured 5, 24 and 72 h after occlusion. Results. IP decreased a lesion area by 37% (p<0/05) and the preliminary introduction ofglibenclamide levelled the effect of IP. A protective effect of PP was similar to that of IP. A decrease in oxygenated R-conformers of Hb-NO and a reverse increase in non-oxygenated T-conformers as well as NO3-и NO2-were noted 5h after MCA occlusion. In the first 24 h after MCA occlusion, contents of NO3-and NO2-returned to normal values. There were changes in the concentrations of Hb-NO complexes as well, with the predominance of R-conformers and minimal contents of T-conformers. Moreover, the correlations between K+ATP channel blockade and the decrease in serum NO3-and NO2 were found (p<0/03). Conclusion. The neuroprotective effect of preconditioning is caused by the activation of K+ATP channels. An analysis of NO metabolite concentrations in the blood of rats with IP suggests that Hb-NO complexes belonging to R-conformers deposit and carry NO in tissues releasing NO accumulated via R→T transfer in conditions of ischemia

Molecular bases of brain preconditioning

© 2017 Deryagin, Gavrilova, Gainutdinov, Golubeva, Andrianov, Yafarova, Buravkov and Koshelev. Preconditioning of the brain induces tolerance to the damaging effects of ischemia and prevents cell death in ischemic penumbra. The development of this phenomenon is mediated by mitochondrial adenosine triphosphate-sensitive potassium (KATP+) channels and nitric oxide signaling (NO). The aim of this study was to investigate the dynamics of molecular changes in mitochondria after ischemic preconditioning (IP) and the effect of pharmacological preconditioning (PhP) with the KATP+-channels opener diazoxide on NO levels after ischemic stroke in rats. Immunofluorescence-histochemistry and laser-confocal microscopy were applied to evaluate the cortical expression of electron transport chain enzymes, mitochondrial KATP+-channels, neuronal and inducible NO-synthases, as well as the dynamics of nitrosylation and nitration of proteins in rats during the early and delayed phases of IP. NO cerebral content was studied with electron paramagnetic resonance (EPR) spectroscopy using spin trapping. We found that 24 h after IP in rats, there is a two-fold decrease in expression of mitochondrial KATP+-channels (p = 0.012) in nervous tissue, a comparable increase in expression of cytochrome c oxidase (p = 0.008), and a decrease in intensity of protein S-nitrosylation and nitration (p = 0.0004 and p = 0.001, respectively). PhP led to a 56% reduction of free NO concentration 72 h after ischemic stroke simulation (p = 0.002). We attribute this result to the restructuring of tissue energy metabolism, namely the provision of increased catalytic sites to mitochondria and the increased elimination of NO, which prevents a decrease in cell sensitivity to oxygen during subsequent periods of severe ischemia

Цитологическая, ультраструктурная характеристика и рентгеноспектральный микроанализ бронхоальвеолярных смывов ликвидаторов последствий аварии на Чернобыльской АЭС в отдаленные сроки (первое сообщение)

Bronchoalveolar lavage (BAL) of 9 young man who took an active part in the liquidation of the Thernobyl wreck’s consequences during may—July 1986 was analyzed in order to investigate: absolute and different cell count; b) possible presence of the radioactive particles in the cytoplasm of alveolar macrophages; c) chemical structure of these particles. Control group — 8 man without lung diseases. Whole absolute cell count in the liquidators BAL was greatly increased in comparison with control group (0,9+0,01-10 /ml and 0,2+0,03-10 / ml in control group) but different cell number was not different from healthy subjects. Cytoplasm of 30—60% of alveolar macrophages contained large (0,5—1,0 mkm in diameter) high density particles. Chemical analysis of these particles was performed by the method of X-ray spectrometry with accerating tension 80 kV, sensitivity of the channel — 40V and number of channels — 1024. Only cytoplasm and part of the high density particles in alveolar macrophages from liquidators contained U, Np, Pu, Fr, Pm, Pa. Cytoplasm of lymphocytes and erytrocytes of these patients, nets, buffers and epon for electron microscopy did’t contained such kind of the elements. Thus, it was determined that alveolar macrophages can take part in the deposition of actually unsoluble radioactive dust particles and parts of nuclear fuel.Проведен анализ бронхоальвеолярных смывов (БАС) 9 молодых мужчин, которые принимали активное участие в ликвидации последствий аварии на Чернобыльской атомной электростанции в мае—июле 1986 года. Целью исследования было: изучение абсолютного и относительного количества клеточных элементов; возможное обнаружение радиоактивных включений в цитоплазме альвеолярных макрофагов; исследование химической структуры этих возможных включений. Абсолютное количество клеток в БАС ликвидаторов было значительно повышено по сравнению с контролем (0,6+0,01-106/мл при 0,2+0,03-106/мл в котроле), однако доля различных клеточных элементов не отличалась от таковых у здоровых лиц. В цитоплазме 40% альвеолярных макрофагов обнаружены крупные (0,5—1,0 мкм в диаметре) оптически плотные частицы. Химический анализ этих включений проводили при помощи метода рентгеновской спектрометрии при усиливающем ускорении 80 kV, чувствительности каналов — 40 V и общем количестве каналов — 1024. Только цитоплазма и часть оптически плотных включений в альвеолярных макрофагах ликвидаторов содержала U, Np, Pu, Fr, Pm, Pa. Цитоплазма лимфоцитов и эритроцитов этих пациентов, а также электронно-микроскопические сеточки, использованные буферы и заливочные смолы не содержали этих элементов. Таким образом, было выявлено, что альвеолярные макрофаги могут принимать участие в депонировании труднорастворимых компонентов радиоактивной пыли и компонентов ядерного топлива