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Abstract
PURPOSE Small and big conductance Ca2+-sensitive potassium (KCa) channels are involved in cardioprotective measures aiming at reducing myocardial reperfusion injury. For levosimendan, infarct size-reducing effects were shown. Whether activation of these channels is involved in levosimendan-induced postconditioning is unknown. We hypothesized that levosimendan exerts a concentration-dependent cardioprotective effect and that both types of Ca2+-sensitive potassium channels are involved. METHODS In a prospective blinded experimental laboratory investigation, hearts of male Wistar rats were randomized and placed on a Langendorff system, perfused with Krebs-Henseleit buffer at a constant pressure of 80 mmHg. All hearts were subjected to 33 min of global ischemia and 60 min of reperfusion. At the onset of reperfusion, hearts were perfused with various concentrations of levosimendan (0.03-1 μM) in order to determine a concentration-response relationship. To elucidate the involvement of KCa-channels for the observed cardioprotection, in the second set of experiments, 0.3 μM levosimendan was administered in combination with the subtype-specific KCa-channel inhibitors paxilline (1 μM, big KCa-channel) and NS8593 (0.1 μM, small KCa-channel) respectively. Infarct size was determined by tetrazolium chloride (TTC) staining. RESULTS Infarct size in controls was 60 ± 7% and 59 ± 6% respectively. Levosimendan at a concentration of 0.3 μM reduced infarct size to 30 ± 5% (P < 0.0001 vs. control). Higher concentrations of levosimendan did not induce a stronger effect. Paxilline but not NS8593 completely abolished levosimendan-induced cardioprotection while both substances alone had no effect on infarct size. CONCLUSIONS Cardioprotection by levosimendan-induced postconditioning shows a binary phenomenon, either ineffective or with maximal effect. The cardioprotective effect requires activation of big but not small KCa channels.
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Bunte S, Behmenburg F, Majewski N, Stroethoff M, Raupach A, Mathes A, Heinen A, Hollmann MW, Huhn R. Characteristics of Dexmedetomidine Postconditioning in the Field of Myocardial Ischemia-Reperfusion Injury. Anesth Analg 2020; 130:90-98. [PMID: 31633505 DOI: 10.1213/ane.0000000000004417] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND Timing and onset of myocardial ischemia are mostly unpredictable. Therefore, postconditioning could be an effective cardioprotective intervention. Because ischemic postconditioning is an invasive and not practicable treatment, pharmacological postconditioning would be a more suitable alternative cardioprotective measure. For the α2-adrenoreceptor agonist, dexmedetomidine postconditioning has been shown. However, data on a concentration-dependent effect of dexmedetomidine are lacking. Furthermore, it is unclear whether the time point and/or duration of dexmedetomidine administration in the reperfusion period is of relevance. We set out to determine whether infarct size reduction by dexmedetomidine is concentration dependent and whether time point and/or duration of dexmedetomidine application has an impact on the effect size of cardio protection. METHODS Hearts of male Wistar rats were randomized and placed on a Langendorff system perfused with Krebs-Henseleit buffer at a constant pressure of 80 mm Hg. All hearts were subjected to 33 minutes of global ischemia and 60 minutes of reperfusion. In part I of the study, a concentration-response effect was determined by perfusing hearts with various concentrations of dexmedetomidine (0.3-100 nM) at the onset of reperfusion. Based on these results, part II of the study was conducted with 3 nM dexmedetomidine. Application of dexmedetomidine started directly at the onset of reperfusion (Dex60) and 15 minutes (Dex15), 30 minutes (Dex30), or 45 minutes (Dex45) after the start of reperfusion and lasted always until the end of the reperfusion period. Infarct size was determined by triphenyltetrazolium chloride staining. RESULTS In part I, infarct size in control (Con) hearts was 62% ± 4%. Three-nanometer dexmedetomidine was the lowest most effective cardioprotective concentration and reduced infarct size to 24% ± 7% (P < .0001 versus Con). Higher concentrations did not confer stronger protection. Infarct size in control hearts from part II was 66% ± 6%. Different starting times and/or durations of application resulted in similar infarct size reduction (all P < .0001 versus Con). CONCLUSIONS Postconditioning by dexmedetomidine is concentration dependent in ranges between 0.3 and 3 nM. Increased concentrations above 3 nM do not further enhance this cardioprotective effect. This cardioprotective effect is independent of time point and length of application in the reperfusion period.
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Affiliation(s)
- Sebastian Bunte
- From the Department of Anesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
| | - Friederike Behmenburg
- From the Department of Anesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
| | - Nicole Majewski
- From the Department of Anesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
| | - Martin Stroethoff
- From the Department of Anesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
| | - Annika Raupach
- From the Department of Anesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
| | - Alexander Mathes
- Department of Anesthesiology, University Hospital Cologne, Cologne, Germany
| | - André Heinen
- Institute of Cardiovascular Physiology, Heinrich-Heine University Duesseldorf, Duesseldorf, Germany
| | - Markus W Hollmann
- Department of Anesthesiology, Amsterdam Universitair Medische Centra (UMC), University of Amsterdam, the Netherlands
| | - Ragnar Huhn
- From the Department of Anesthesiology, University Hospital Duesseldorf, Duesseldorf, Germany
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Dai W, Shi J, Carreno J, Kloner RA. Different Effects of Volatile and Nonvolatile Anesthetic Agents on Long-Term Survival in an Experimental Model of Hemorrhagic Shock. J Cardiovasc Pharmacol Ther 2020; 25:346-353. [PMID: 32292050 DOI: 10.1177/1074248420919221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND We investigated whether the cardioprotective, volatile gas anesthetic agent, isoflurane, could improve survival and organ function from hemorrhagic shock in an experimental rat model, compared to standard nonvolatile anesthetic agent ketamine/xylazine. METHODS Sprague Dawley rats (both genders) were randomized to receive either intraperitoneal ketamine/xylazine (K/X, 90 and 10 mg/kg; n = 12) or isoflurane (5% isoflurane induction and 2% maintenance in room air; n = 12) for anesthesia. Blood was withdrawn to maintain mean arterial blood pressure at 30 mm Hg for 1 hour, followed by 30 minutes of resuscitation with shed blood. Rats were allowed to recover and survive for 6 weeks. RESULTS During the shock phase, the total withdrawn blood volume (expressed as % of estimated total blood volume) to maintain a level of hypotension of 30 mm Hg was significantly higher in the isoflurane group (51.0% ± 1.5%) than in the K/X group (45.3% ± 1.8%; P = .023). Recovery of blood pressure during the resuscitation phase was significantly improved in the isoflurane group compared to the K/X group. The survival rate at 6 weeks was 1 (8.3%) of 12 in rats receiving K/X and 10 (83.3%) of 12 in rats receiving isoflurane (P < .001). Histology performed at 6 weeks demonstrated brain infarction in the 1 surviving rat receiving K/X; no brain infarction occurred in the 10 surviving rats that received isoflurane. No infarction was detected in heart, lung, liver, or kidneys among the surviving rats. CONCLUSIONS Isoflurane improved blood pressure response to resuscitation and resulted in significantly higher long-term survival rate.
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Affiliation(s)
- Wangde Dai
- HMRI Cardiovascular Research Institute, Huntington Medical Research Institutes, Pasadena, CA, USA.,Division of Cardiovascular Medicine of the Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Jianru Shi
- HMRI Cardiovascular Research Institute, Huntington Medical Research Institutes, Pasadena, CA, USA.,Division of Cardiovascular Medicine of the Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Juan Carreno
- HMRI Cardiovascular Research Institute, Huntington Medical Research Institutes, Pasadena, CA, USA
| | - Robert A Kloner
- HMRI Cardiovascular Research Institute, Huntington Medical Research Institutes, Pasadena, CA, USA.,Division of Cardiovascular Medicine of the Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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Guo Y, Wang Y, Zhang D, Cui C, Li T, Wang S. [Effect of ulinastatin on isoflurane-induced neuronal apoptosis in the hippocampus of rats]. NAN FANG YI KE DA XUE XUE BAO = JOURNAL OF SOUTHERN MEDICAL UNIVERSITY 2019; 39:850-854. [PMID: 31340920 DOI: 10.12122/j.issn.1673-4254.2019.07.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To investigate the effect of ulinastatin pretreatment on isoflurane-induced mitochondria-dependent neuronal apoptosis in the hippocampus of rats. METHODS Thirty-six male SD rats were randomly assigned into control group, isoflurane group and ulinastatin group. In the latter two groups, the rats were subjected to acute exposure to 0.75% isoflurane for 6 h and pretreated with 50 000 U/kg of ulinastatin before isoflurane exposure, respectively. After the treatments, apoptosis of the hippocampal neurons was detected using TUNEL assay, and the mitochondrial membrane potential (△ ψm) was measured using JC-1 mitochondrial membrane potential kit; cytochrome C release and caspase-3 activity were examined with Western blotting, and intracellular reactive oxygen species (ROS) was detected using the fluorescent probe H2DCFDA. RESULTS Compared with those in the control group, the rats with acute exposure to isoflurane showed markedly increased TUNEL-positive cells in the hippocampus (P < 0.05), which were obviously reduced by ulinastatin pretreatment (P < 0.05). The △ψm of the hippocampal neurons was significantly reduced after isoflurane exposure (P < 0.05), and was partly recovered by ulinastatin pretreatment (P < 0.05). Acute exposure to isoflurane resulted in obviously increased cellular ROS, cytochrome C release and caspase-3 activity in the hippocampal neurons (P < 0.05), and these changes were significantly inhibited by ulinastatin pretreatment (P < 0.05). CONCLUSIONS Ulinastatin pretreatment provides neuroprotection against isoflurane-induced apoptosis of the hippocampal neurons in rats possibly by inhibiting mitochondria-dependent apoptosis pathway.
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Affiliation(s)
- Yuanbo Guo
- Department of Anesthesiology of Medical Sciences, Guangzhou 510080, China
| | - Yan Wang
- Department of Science and Education, Guangdong Provincial People's Hospital/Guangdong Academy of Medical Sciences, Guangzhou 510080, China
| | - Dengwen Zhang
- Department of Anesthesiology of Medical Sciences, Guangzhou 510080, China
| | - Can Cui
- Department of Anesthesiology of Medical Sciences, Guangzhou 510080, China
| | - Tao Li
- Department of Critical Care Medicine, Chenzhou First People's Hospital, Chenzhou 423000, China
| | - Sheng Wang
- Department of Anesthesiology of Medical Sciences, Guangzhou 510080, China
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Bunte S, Behmenburg F, Bongartz A, Stroethoff M, Raupach A, Heinen A, Minol JP, Hollmann MW, Huhn R, Sixt SU. Preconditioning by Levosimendan is Mediated by Activation of Mitochondrial Ca2+-Sensitive Potassium (mBKCa) Channels. Cardiovasc Drugs Ther 2018; 32:427-434. [DOI: 10.1007/s10557-018-6819-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Juhász V, Hornyik T, Benák A, Nagy N, Husti Z, Pap R, Sághy L, Virág L, Varró A, Baczkó I. Comparison of the effects of I K,ACh, I Kr, and I Na block in conscious dogs with atrial fibrillation and on action potentials in remodeled atrial trabeculae. Can J Physiol Pharmacol 2017; 96:18-25. [PMID: 28892643 DOI: 10.1139/cjpp-2017-0342] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and a major cause of morbidity and mortality. Traditional antiarrhythmic agents used for restoration of sinus rhythm have limited efficacy in long-term AF and they may possess ventricular proarrhythmic adverse effects, especially in patients with structural heart disease. The acetylcholine receptor-activated potassium channel (IK,ACh) represents an atrial selective target for future AF management. We investigated the effects of the IK,ACh blocker tertiapin-Q (TQ), a derivative of the honeybee toxin tertiapin, on chronic atrial tachypacing-induced AF in conscious dogs, without the influence of anesthetics that modulate a number of cardiac ion channels. Action potentials (APs) were recorded from right atrial trabeculae isolated from dogs with AF. TQ significantly and dose-dependently reduced AF incidence and AF episode duration, prolonged atrial effective refractory period, and prolonged AP duration. The reference drugs propafenone and dofetilide, both used in the clinical management of AF, exerted similar effects against AF in vivo. Dofetilide prolonged atrial AP duration, whereas propafenone increased atrial conduction time. TQ and propafenone did not affect the QT interval, whereas dofetilide prolonged the QT interval. Our results show that inhibition of IK,ACh may represent a novel, atrial-specific target for the management of AF in chronic AF.
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Affiliation(s)
- Viktor Juhász
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Tibor Hornyik
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Attila Benák
- b 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Szeged, Hungary
| | - Norbert Nagy
- c MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zoltán Husti
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - Róbert Pap
- b 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Szeged, Hungary
| | - László Sághy
- b 2nd Department of Internal Medicine and Cardiology Centre, University of Szeged, Szeged, Hungary
| | - László Virág
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
| | - András Varró
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary.,c MTA-SZTE Research Group of Cardiovascular Pharmacology, Hungarian Academy of Sciences, Szeged, Hungary
| | - István Baczkó
- a Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary
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Krabbendam IE, Honrath B, Culmsee C, Dolga AM. Mitochondrial Ca 2+-activated K + channels and their role in cell life and death pathways. Cell Calcium 2017; 69:101-111. [PMID: 28818302 DOI: 10.1016/j.ceca.2017.07.005] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2017] [Revised: 07/14/2017] [Accepted: 07/14/2017] [Indexed: 12/18/2022]
Abstract
Ca2+-activated K+ channels (KCa) are expressed at the plasma membrane and in cellular organelles. Expression of all KCa channel subtypes (BK, IK and SK) has been detected at the inner mitochondrial membrane of several cell types. Primary functions of these mitochondrial KCa channels include the regulation of mitochondrial ROS production, maintenance of the mitochondrial membrane potential and preservation of mitochondrial calcium homeostasis. These channels are therefore thought to contribute to cellular protection against oxidative stress through mitochondrial mechanisms of preconditioning. In this review, we summarize the current knowledge on mitochondrial KCa channels, and their role in mitochondrial function in relation to cell death and survival pathways. More specifically, we systematically discuss studies on the role of these mitochondrial KCa channels in pharmacological preconditioning, and according protective effects on ischemic insults to the brain and the heart.
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Affiliation(s)
- Inge E Krabbendam
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands.
| | - Birgit Honrath
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands; Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany.
| | - Carsten Culmsee
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany.
| | - Amalia M Dolga
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands.
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