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Examination of the Changes in Calcium Homeostasis in the Delayed Antiarrhythmic Effect of Sodium Nitrite. Int J Mol Sci 2019; 20:ijms20225687. [PMID: 31766239 PMCID: PMC6888494 DOI: 10.3390/ijms20225687] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 11/09/2019] [Accepted: 11/11/2019] [Indexed: 01/11/2023] Open
Abstract
We have evidence that the intravenous infusion of sodium nitrite (NaNO2) results in an antiarrhythmic effect when given 24 h prior to an ischemia and reperfusion (I/R) insult in anaesthetized dogs. This protection was associated with the reduction of reactive oxygen species resulting from I/R through the attenuation of mitochondrial respiration. Here, we examined whether the changes in calcium, which also contributes to arrhythmia generation, play a role in the NaNO2-induced effect. On the first day, 30 anaesthetized dogs were treated either with saline or NaNO2 (0.2 µmol/kg/min) for 20 min. Some animals were subjected to a 25 min LAD (anterior descending branch of the left coronary artery) occlusion and 2 min reperfusion (I/R = 4; NaNO2-I/R = 6), or the heart was removed 24 h later. We have shown that nitrite prevented the I/R-induced increase in cellular and mitochondrial calcium deposits. During simulated I/R, the amplitude of the calcium transient and the diastolic calcium level were significantly lower in the nitrite-treated hearts and the ERP (effective refractory period) fraction of the action potential was significantly increased. Furthermore, nitrite also enhanced the mitochondrial respiratory response and prevented the MPTPT opening during calcium overload. These results suggest that nitrite can reduce the harmful consequences of calcium overload, perhaps directly by modulating ion channels or indirectly by reducing the mitochondrial ROS (reactive oxygen species) production.
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Jones DA, Rathod KS, Williamson A, Harrington D, Andiapen M, van Eijl S, Westwood M, Antoniou S, Schilling RJ, Ahluwalia A, Mathur A. The effect of intracoronary sodium nitrite on the burden of ventricular arrhythmias following primary percutaneous coronary intervention for acute myocardial infarction. Int J Cardiol 2019; 266:1-6. [PMID: 29887423 DOI: 10.1016/j.ijcard.2018.01.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 01/06/2018] [Accepted: 01/08/2018] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Pre-clinical evidence suggests delivery of nitric oxide (NO) through administration of inorganic nitrite suppresses arrhythmias resulting from acute ischaemia and reperfusion (I/R). To date no assessment of whether inorganic nitrite might limit reperfusion arrhythmia has occurred in man, therefore we explored the effects on I/R-induced ventricular arrhythmias in the NITRITE-AMI cohort. METHODS In the NITRITE-AMI cohort, Holter analysis was performed prior to and for 24 h after primary PCI in 80 patients who received either intra-coronary sodium nitrite (N = 40) or placebo (N = 40) during primary PCI for AMI. RESULTS Ventricular rhythm disturbance was experienced by 100% patients; however, there was no difference in the number between the groups, p = .2196. Non-sustained ventricular tachycardia (NSVT) occurred in 67.5% (27/40) of nitrite-treated patients compared to 89% (35/39) of those treated with placebo (p = .027). There was a significant reduction in both the number of runs (63%, p ≤.0001) and total beats of NSVT (64%, p = .0019) in the nitrite-treated patients compared to placebo. Post-hoc analyses demonstrate a direct correlation of occurrence of NSVT with infarct size, with the correlation stronger in the placebo versus the nitrite group initiating an independent nitrite effect (Nitrite: r = 0.110, p = .499, placebo: r = 0.527, p = .001, p for comparison: 0.004). CONCLUSION Overall no difference in ventricular rhythm disturbance was seen with intra-coronary nitrite treatment during primary PCI in STEMI patients, however nitrite treatment was associated with an important reduction in the incidence and severity of NSVT. In view of the sustained reduction of MACE seen, this effect warrants further study in a large-scale trial.
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Affiliation(s)
- Daniel A Jones
- Centre of Clinical Pharmacology, William Harvey Research Institute, Barts & The London Medical School, Queen Mary University of London, United Kingdom; Department of Cardiology, Barts Heart Centre, Barts Health NHS Trust, United Kingdom.
| | - Krishnaraj S Rathod
- Centre of Clinical Pharmacology, William Harvey Research Institute, Barts & The London Medical School, Queen Mary University of London, United Kingdom; Department of Cardiology, Barts Heart Centre, Barts Health NHS Trust, United Kingdom
| | - Anna Williamson
- Department of Cardiology, Barts Heart Centre, Barts Health NHS Trust, United Kingdom
| | - Deirdre Harrington
- Department of Cardiology, Barts Heart Centre, Barts Health NHS Trust, United Kingdom
| | - Mervyn Andiapen
- Department of Cardiology, Barts Heart Centre, Barts Health NHS Trust, United Kingdom
| | - Sven van Eijl
- Centre of Clinical Pharmacology, William Harvey Research Institute, Barts & The London Medical School, Queen Mary University of London, United Kingdom
| | - Mark Westwood
- Department of Cardiology, Barts Heart Centre, Barts Health NHS Trust, United Kingdom
| | - Sotiris Antoniou
- Department of Cardiology, Barts Heart Centre, Barts Health NHS Trust, United Kingdom
| | - Richard J Schilling
- Department of Cardiology, Barts Heart Centre, Barts Health NHS Trust, United Kingdom
| | - Amrita Ahluwalia
- Centre of Clinical Pharmacology, William Harvey Research Institute, Barts & The London Medical School, Queen Mary University of London, United Kingdom
| | - Anthony Mathur
- Centre of Clinical Pharmacology, William Harvey Research Institute, Barts & The London Medical School, Queen Mary University of London, United Kingdom; Department of Cardiology, Barts Heart Centre, Barts Health NHS Trust, United Kingdom
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Demeter-Haludka V, Juhász L, Kovác M, Gardi J, Végh Á. Is there a role of inducible nitric oxide synthase activation in the delayed antiarrhythmic effect of sodium nitrite? Can J Physiol Pharmacol 2016; 95:447-454. [PMID: 28177694 DOI: 10.1139/cjpp-2016-0357] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study aimed to examine whether inducible nitric oxide synthase (iNOS) plays a role in the delayed antiarrhythmic effect of sodium nitrite. Twenty-one dogs were infused intravenously with sodium nitrite (0.2 μmol·kg-1·min-1) for 20 min, either in the absence (n = 12) or in the presence of the iNOS inhibitor S-(2-aminoethyl)-isothiourea (AEST) (total dose 2.0 mg·kg-1 i.v., n = 9). Control dogs (n = 12) were given saline. Twenty-four hours later, all of the dogs were subjected to a 25 min period occlusion of the left anterior descending coronary artery followed by rapid reperfusion. Dogs treated with AEST and nitrite received again AEST prior to the occlusion. Compared with the controls, sodium nitrite markedly reduced the number of ectopic beats, the number and incidence of ventricular tachycardia, and the incidence of ventricular fibrillation during occlusion and increased survival (0% versus 50%) from the combined ischaemia and reperfusion insult. Although AEST completely inhibited iNOS activity, the nitrite-induced increase in NO bioavailability during occlusion was not substantially modified. Furthermore, AEST attenuated but did not completely abolish the antiarrhythmic effect of nitrite. The marked delayed antiarrhythmic effect of sodium nitrite is not entirely due to the activation of iNOS; other mechanisms may certainly play a role.
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Affiliation(s)
- Vivien Demeter-Haludka
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Albert-Szent Györgyi Medical Centre, Szeged H-6720, Hungary
| | - László Juhász
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Albert-Szent Györgyi Medical Centre, Szeged H-6720, Hungary
| | - Mária Kovác
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Albert-Szent Györgyi Medical Centre, Szeged H-6720, Hungary
| | - János Gardi
- b First Department of Internal Medicine, University of Szeged, Albert-Szent Györgyi Medical Centre, Szeged H-6720, Hungary
| | - Ágnes Végh
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Albert-Szent Györgyi Medical Centre, Szeged H-6720, Hungary
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Kovács M, Kiss A, Gönczi M, Miskolczi G, Seprényi G, Kaszaki J, Kohr MJ, Murphy E, Végh Á. Effect of sodium nitrite on ischaemia and reperfusion-induced arrhythmias in anaesthetized dogs: is protein S-nitrosylation involved? PLoS One 2015; 10:e0122243. [PMID: 25909651 PMCID: PMC4409072 DOI: 10.1371/journal.pone.0122243] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 02/18/2015] [Indexed: 11/21/2022] Open
Abstract
Background and Purpose To provide evidence for the protective role of inorganic nitrite against acute ischaemia and reperfusion-induced ventricular arrhythmias in a large animal model. Experimental Approach Dogs, anaesthetized with chloralose and urethane, were administered intravenously with sodium nitrite (0.2 µmolkg-1min-1) in two protocols. In protocol 1 nitrite was infused 10 min prior to and during a 25 min occlusion of the left anterior descending (LAD) coronary artery (NaNO2-PO; n = 14), whereas in protocol 2 the infusion was started 10 min prior to reperfusion of the occluded vessel (NaNO2-PR; n = 12). Control dogs (n = 15) were infused with saline and subjected to the same period of ischaemia and reperfusion. Severities of ischaemia and ventricular arrhythmias, as well as changes in plasma nitrate/nitrite (NOx) levels in the coronary sinus blood, were assessed throughout the experiment. Myocardial superoxide and nitrotyrosine (NT) levels were determined during reperfusion. Changes in protein S-nitrosylation (SNO) and S-glutathionylation were also examined. Key Results Compared with controls, sodium nitrite administered either pre-occlusion or pre-reperfusion markedly suppressed the number and severity of ventricular arrhythmias during occlusion and increased survival (0% vs. 50 and 92%) upon reperfusion. There were also significant decreases in superoxide and NT levels in the nitrite treated dogs. Compared with controls, increased SNO was found only in NaNO2-PR dogs, whereas S-glutathionylation occurred primarily in NaNO2-PO dogs. Conclusions Intravenous infusion of nitrite profoundly reduced the severity of ventricular arrhythmias resulting from acute ischaemia and reperfusion in anaesthetized dogs. This effect, among several others, may result from an NO-mediated reduction in oxidative stress, perhaps through protein SNO and/or S-glutathionylation.
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Affiliation(s)
- Mária Kovács
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Attila Kiss
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Márton Gönczi
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - Gottfried Miskolczi
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - György Seprényi
- Department of Medical Biology, Faculty of Medicine, University of Szeged, Szeged, Hungary
| | - József Kaszaki
- Institute of Surgical Research, Albert Szent-Györgyi Medical Center, University of Szeged, Szeged, Hungary
| | - Mark J Kohr
- Systems Biology Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Elizabeth Murphy
- Systems Biology Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Ágnes Végh
- Department of Pharmacology and Pharmacotherapy, Faculty of Medicine, University of Szeged, Szeged, Hungary
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Kisvári G, Kovács M, Gardi J, Seprényi G, Kaszaki J, Végh Á. The effect of acute simvastatin administration on the severity of arrhythmias resulting from ischaemia and reperfusion in the canine: Is there a role for nitric oxide? Eur J Pharmacol 2014; 732:96-104. [DOI: 10.1016/j.ejphar.2014.03.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 03/14/2014] [Accepted: 03/21/2014] [Indexed: 02/09/2023]
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Végh A, Gönczi M, Miskolczi G, Kovács M. Regulation of gap junctions by nitric oxide influences the generation of arrhythmias resulting from acute ischemia and reperfusion in vivo. Front Pharmacol 2013; 4:76. [PMID: 23785332 PMCID: PMC3682124 DOI: 10.3389/fphar.2013.00076] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 05/29/2013] [Indexed: 11/13/2022] Open
Abstract
Myocardial ischemia resulting from sudden occlusion of a coronary artery is one of the major causes in the appearance of severe, often life-threatening ventricular arrhythmias. Although the underlying mechanisms of these acute arrhythmias are many and varied, there is no doubt that uncoupling of gap junctions (GJs) play an important role especially in arrhythmias that are generated during phase Ib, and often terminate in sudden cardiac death. In the past decades considerable efforts have been made to explore mechanisms which regulate the function of GJs, and to find new approaches for protection against arrhythmias through the modulation of GJs. These investigations led to the development of GJ openers and inhibitors. The pharmacological modulation of GJs, however, resulted in conflicting results. It is still not clear whether opening or closing of GJs would be advantageous for the ischemic myocardium. Both maneuvers can result in protection, depending on the models, endpoints and the time of opening and closing of GJs. Furthermore, although there is substantial evidence that preconditioning decreases or delays the uncoupling of GJs, the precise mechanisms by which this attains have not yet been elucidated. In our own studies in anesthetized dogs preconditioning suppressed the ischemia and reperfusion-induced ventricular arrhythmias, and this protection was associated with the preservation of GJ function, manifested in less marked changes in electrical impedance, as well as in the maintenance of GJ permeability and phosphorylation of connexin43. Since we have substantial previous evidence that nitric oxide (NO) is an important trigger and mediator of the preconditioning-induced antiarrhythmic protection, we hypothesized that NO, among its several effects, may lead to this protection by influencing cardiac GJs. The hypotheses and theories relating to the pharmacological modulation of GJs will be discussed with particular attention to the role of NO.
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Affiliation(s)
- Agnes Végh
- Department of Pharmacology and Pharmacotherapy, University of Szeged Szeged, Hungary
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Is there a trigger role of peroxynitrite in the anti-arrhythmic effect of ischaemic preconditioning and peroxynitrite infusion? Eur J Pharmacol 2011; 667:306-13. [DOI: 10.1016/j.ejphar.2011.06.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 05/26/2011] [Accepted: 06/06/2011] [Indexed: 02/04/2023]
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Kiss A, Juhász L, Seprényi G, Kupai K, Kaszaki J, Végh A. The role of nitric oxide, superoxide and peroxynitrite in the anti-arrhythmic effects of preconditioning and peroxynitrite infusion in anaesthetized dogs. Br J Pharmacol 2010; 160:1263-72. [PMID: 20590618 DOI: 10.1111/j.1476-5381.2010.00774.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Both ischaemia preconditioning (PC) and the intracoronary infusion of peroxynitrite (PN) suppress ischaemia and reperfusion (I/R)-induced arrhythmias and the generation of nitrotyrosine (NT, a marker of PN). However, it is still unclear whether this latter effect is due to a reduction in nitric oxide (NO) or superoxide (O(2)(-)) production. EXPERIMENTAL APPROACH Dogs anaesthetized with chloralose and urethane were infused, twice for 5 min, with either saline (control) or 100 nM PN, or subjected to similar periods of occlusion (PC), 5 min prior to a 25 min occlusion and reperfusion of the left anterior descending coronary artery. Severities of ischaemia and ventricular arrhythmias, as well as changes in the coronary sinus nitrate/nitrite (NOx) levels were assessed throughout the experiment. The production of myocardial NOx, O(2)(-) and NT was determined following reperfusion. KEY RESULTS Both PC and PN markedly suppressed the I/R-induced ventricular arrhythmias, compared to the controls, and increased NOx levels during coronary artery occlusion. Reperfusion induced almost the same increases in NOx levels in all groups, but superoxide production and, consequently, the generation of NT were significantly less in PC- and PN-treated dogs than in controls. CONCLUSIONS AND IMPLICATIONS Since both PC and the administration of PN enhanced NOx levels during I/R, the attenuation of endogenous PN formation in these dogs is primarily due to a reduction in the amount of O(2) produced. Thus, the anti-arrhythmic effect of PC and PN can almost certainly be attributed to the preservation of NO availability during myocardial ischaemia.
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Affiliation(s)
- Attila Kiss
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Albert Szent-Györgyi Medical Center, Szeged, Hungary
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Lascano EC, Valle HFD, Negroni JA. Nitroglycerin induces late preconditioning against arrhythmias but not stunning in conscious sheep. SCAND CARDIOVASC J 2009; 41:160-6. [PMID: 17487765 DOI: 10.1080/14017430701329295] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
OBJECTIVES Nitroglycerin, a nitric oxide donor, induces late preconditioning against stunning by short ischemia-reperfusion periods. The study purpose was to assess similar nitroglycerin protection against stunning and arrhythmias produced by prolonged reversible ischemia. DESIGN Four groups of conscious sheep were studied, control: 12 minutes ischemia and 2 hour reperfusion; late preconditioning: six periods of 5 min ischemia-5 min reperfusion 24 h before 12 min ischemia and late preconditioning with 120 microg/kg and 600 microg/kg nitroglycerin administered instead of the ischemia-reperfusion periods. RESULTS Although late preconditioning protected against stunning (mean postischemic recovery of wall thickening fraction, control (n=10): 54.8+/-3.2, late preconditioning (n=9): 74.4+/-3.0, p<0.01), nitroglycerin 120 microg/kg (n=6) did not reproduce mechanical protection (50.1+/-3.8), even with a higher concentration of 600 microg/kg (59.1+/-3.7, n=4). However, nitroglycerin decreased arrhythmia severity index (control: 2.3+/-0.6, late preconditioning: 0.5+/-0.4, nitroglycerin 120 microg/kg: 1+/-0.4 and 600 microg/kg: 0.1+/-0.1 (p<0.05 vs. control). CONCLUSIONS Nitroglycerin only has a limited late preconditioning protective effect in conscious animals submitted to a reversible prolonged ischemia since it protects against arrhythmias but not against stunning.
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Affiliation(s)
- Elena C Lascano
- Department of Physiology, Pharmacology and Biochemistry, Favaloro University, Buenos Aires, Argentina.
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Gönczi M, Papp R, Kovács M, Seprényi G, Végh A. Modulation of gap junctions by nitric oxide contributes to the anti-arrhythmic effect of sodium nitroprusside? Br J Pharmacol 2009; 156:786-93. [PMID: 19239476 DOI: 10.1111/j.1476-5381.2008.00089.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE Nitric oxide (NO) donors provide a preconditioning-like anti-arrhythmic protection in the anaesthetized dog. As NO may modulate gap junction (GJ) function, the present study investigated whether this anti-arrhythmic effect is due to a modification of GJs by NO, derived from the NO donor sodium nitroprusside (SNP). EXPERIMENTAL APPROACH In chloralose-urethane-anaesthetized, open-chest dogs, either saline (controls; n= 11) or SNP (0.2 microg x kg(-1) x min(-1); n= 10) was infused at a rate of 0.5 mL x min(-1) by the intracoronary route. The infusions were started 20 min prior to and maintained throughout the entire 60 min occlusion period of the left anterior descending coronary artery. The severity of ischaemia and of arrhythmias, tissue electrical impedance and permeability, as well as the phosphorylation of connexin43, were assessed. KEY RESULTS Compared with the controls, SNP infusion markedly suppressed the total number of ventricular premature beats (666 +/- 202 vs. 49 +/- 18; P < 0.05), and the number of ventricular tachycardiac episodes (8.1 +/- 2.3 vs. 0.2 +/- 0.1; P < 0.05) without significantly modifying the incidence of ventricular tachycardia or ventricular fibrillation. The severity of ischaemia (epicardial ST-segment changes, inhomogeneity of electrical activation) and tissue electrical impedance changes were significantly less in the SNP-treated dogs. SNP improved GJ permeability and preserved the phosphorylated form of connexin43. CONCLUSION AND IMPLICATIONS The anti-arrhythmic protection resulting from SNP infusion in the anaesthethized dog may, in part, be associated with the modulation of gap junctional function by NO.
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Affiliation(s)
- Márton Gönczi
- Department of Pharmacology and Pharmacotherapy, University of Szeged, Albert Szent-Györgyi Faculty of Medicine, Szeged, Hungary.
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Kiss A, Juhász L, Huliák I, Végh A. Peroxynitrite decreases arrhythmias induced by ischaemia reperfusion in anaesthetized dogs, without involving mitochondrial KATP channels. Br J Pharmacol 2008; 155:1015-24. [PMID: 18846034 DOI: 10.1038/bjp.2008.344] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND AND PURPOSE Exogenous peroxynitrite from nanomolar to micromolar concentrations exerts cardioprotection. Here, we have assessed its effects on ischaemia- and reperfusion-induced ventricular arrhythmias in vivo and a possible role for mitochondrial K(ATP) channels in these effects, using the channel inhibitor 5-hydroxydecanoate (5-HD). EXPERIMENTAL APPROACH Chloralose-urethane-anaesthetized dogs were treated twice for 5 min with peroxynitrite (100 nM, by intracoronary infusions) in both the absence and presence of 5-HD (150 microg kg(-1) min(-1)), and then subjected to 25 min occlusion of the left anterior descending coronary artery. The severity of ischaemia and of arrhythmias, as well as the levels of nitrotyrosine were assessed and compared with a group of control dogs, subjected only to a 25 min occlusion and reperfusion insult. KEY RESULTS Compared with controls, infusion of peroxynitrite markedly suppressed the number of ventricular premature beats (388+/-88 vs 133+/-44), the incidence of ventricular fibrillation both during occlusion (50% vs 10%) and reperfusion (100% vs 44%), and increased survival (0% vs 50%; all P<0.05). The severity of ischaemia (epicardial ST-segment changes, inhomogeneity of electrical activation) during occlusion and nitrotyrosine levels on reperfusion were significantly less in the peroxynitrite-treated dogs than in the controls. 5-HD did not modify the cardioprotective effects of peroxynitrite. CONCLUSION AND IMPLICATIONS Exogenous peroxynitrite provided antiarrhythmic protection in vivo, which might have been on account of a reduction in endogenous peroxynitrite formation. This protection seemed not to be mediated through mitoK(ATP) channels.
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Affiliation(s)
- A Kiss
- 1Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical Center, University of Szeged, Hungary
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